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Fragmentation of plastic objects in a laboratory seawater microcosm

Abstract

We studied the fragmentation of conventional thermoplastic and compostable plastic items in a laboratory seawater microcosm. In the microcosm, polyurethane foams, cellulose acetate cigarette filters, and compostable polyester and polylactic acid items readily sank, whereas polyethylene air pouches, latex balloons, polystyrene foams and polypropylene cups remained afloat. Microbial biofilms dominated by Cyanobacteria, Proteobacteria, Planctomycetes and Bacteriodetes grew on the plastics, and caused some of the polyethylene items to sink to the bottom. Electrical resistances (ER) of plastic items decreased as function of time, an indication that seawater had penetrated into microscopic crevices in the plastic that had developed over time. Rate constants for ER decrease in polyethylene items in the microcosm were similar to tensile elongation decrease of polyethylene sheets floating in sea, measured previously by others. Weight loss of plastic items was ≤ 1% per year for polyethylene, polystyrene and polypropylene, 3–5% for latex, polyethylene terephthalate and polyurethane, 15% for cellulose acetate, and 7–27% for polyester and polylactic acid compostable bags. The formation of microplastics observed in the microcosm was responsible for at least part of the weight loss. This study emphasizes the need to obtain experimental data on plastic litter degradation under conditions that are realistic for marine environments.

Introduction

Millions of tonnes of plastic waste are estimated to enter the oceans annually1,2. The issue of widespread plastic waste in the environment is exacerbated by the durability and persistence of these materials in the environment3,4,5,6,7,8,9,10,11,12,13,14,15,16,17. In the marine environment plastic breaks up into smaller particles18,19,20. An estimated 13% to 32% of the total weight of buoyant plastics in the oceans consists of microplastic particles of 0.3–5 mm in size14,21,22. It is currently unknown how and at which rates fragmentation of plastic proceeds. We also do not know to which degree biodegradation contributes to the mineralization of plastic in seawater23,24,25,26,27,28,29,30,31,32. This lack of data limits our capability to assess and predict the fate and residence times of plastic litter in marine ecosystems. The present study sought to shed some light on plastic litter fate in a marine microcosm to learn more about the processes and rates that could be observed.

Fragmentation of plastics is thought to be initiated by polymer chain backbone weathering through exposure to sunlight (UV), oxidants, hydrolysis and physical shearing, for example through currents, waves, or friction with sand4,33,34,35,36,37,38,39,40. The oxidation and shortening of polymer chains and leaching of plasticizers makes plastic materials brittle and stimulates the formation of surface cracks and fragmentation18,19. As a result micro- and nanometer sized plastic particles may be released from the surface of larger fragments19. In time this can result in the generation of numerous micro- and nanoplastic particles from a single plastic object18. In theory, one bag composed of two plastic sheets 50 cm × 40 cm × 50 µm thick could generate 20 particles with a volume of 1 mm3, 20 million particles with a volume of 1 µm3 or 20 trillion particles with a volume of 1 nm3.

The size of the plastic particles is important because it affects their potential hazard to individual organisms, communities, and ecosystems. Larger plastic litter items may be eaten by or cause entanglement of marine fish, birds and mammals, while the micro- and nanoplastic particles are more prone to being ingested not only by large, but also by smaller invertebrates such as mussels and zooplankton with the potential for accumulation in food chains19,41.

Fragmentation also affects plastic litter transport through marine systems because smaller particles are transported differently horizontally and vertically than larger items42,43,44,45,46,47,48. Smaller particles have a relatively large exposed surface area compared to their volume. This may result in increased degradation rates, adsorption sites per unit mass and reduced buoyancy (upon biofouling), resulting in transfer of microplastic particles from the sea surface to the water column or sediment9,11,14,18,48. The larger specific surface area generated through fragmentation increases contact with water with faster leaching or sorption rates for chemicals and additional area for biofouling49.

In 2018, about 359 million tonnes plastic were produced globally, of which 62 million tonnes in Europe. About 80% consisted of thermoplastics with polymer backbones of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane (PU), polystyrene (PS) or polyethylene terephthalate (PET)50. The material composition, e.g. chain backbone, crosslinking and additives, affects to a high degree the repertoire of mechanisms and rates of abiotic and biological degradation that can occur. Polymers with a carbon–carbon backbone, high molecular weight, and few functional groups, such as PE, PP, PS and PVC, are very resistant to degradation9. Ultraviolet (UV) light from the sun produces breaks in for example PE, PP, PS and PVC polymer chains. But in marine ecosystems such plastic particles are readily transferred downwards and often become buried in the sediment. Floating plastic particles become rapidly covered by biofilms, which protect them from UV radiation51,52 and weigh them down, causing them to sink. The timescale of the mineralization process of most plastic materials with a carbon–carbon backbone in the marine environment is usually estimated at decades or longer9,24,33,38.

Plastic materials with heteroatoms in the main polymer chain are susceptible to hydrolysis9. In the marine environment, cleavage of the ester bonds in PET and PU and amide bonds in nylon can occur through abiotic hydrolysis, photolysis and oxidation. In addition, biodegradation of PET and PU may be significant, since microorganisms that are capable of this process can readily be isolated from the environment, including marine systems26,27,30,53,54.

Microorganisms in biofilms are sometimes able to catalyze the partial or complete mineralization of plastic to energy, biomass and inorganic molecules such as carbon dioxide, water, and/or methane, hydrogen and ammonia21,22,23,24,25,26,27,28,29,30,53,54,55,56,57,58,59,60,61. The biodegradability of plastic materials is usually determined under conditions optimized for high metabolic rate (temperature, nutrients, pH) such as in sewage sludge, landfill, soil or compost, but not under conditions which prevail in marine environments57. Therefore, such tests are unreliable indicators of the fate of plastic items in the sea.

One way proposed to reduce the persistence of plastic objects in the environment is to use polymers that mineralize more readily through biodegradation58. Natural resources such as cellulose, starch, polylactic acid (PLA), and polyhydroxyalkanoates (PHA) are often used for the production of biodegradable plastics58,59,60. Internationally recognized standards, EN 13,432 (European), ASTM 6400 (USA) or ISO 17088 (International) are used to define and label the biodegradability of plastic materials59,60. According to these standards, a plastic product can be “compostable-labelled” if at least 90% (weight) disintegrates into particles that pass through a 2 × 2 mm mesh within 3 months and mineralize within 6 months in an industrial composting environment. According to these laboratory tests, plastic items are mixed with biowaste and typically exposed at temperatures in the range between 40 and 60 °C. Obviously, these tests do not represent the conditions prevailing in the marine environment, which points out the need to assess the fragmentation and biodegradation of compostable-labelled plastic materials in seawater.

Fragmentation rates of plastic litter are likely to vary widely according to environmental conditions and the plastic material grade in question. The rates will also not be constant in time, as the degradation results from a variety of independent and interdependent processes (e.g.biodegradation, hydrolysis, photooxidation, erosion, cracking, etc.) that do not proceed at the same rates and do not stay constant over time. Such rates have only been roughly estimated in outdoor exposure experiments in seawater, with rare attempts to determine loss of tensile strength or surface area4,19,33,38. The rates at which we can expect plastics to completely mineralize in the sea are expected to be very low and challenging to empirically measure or quantify61.

Quantifying weathering, fragmentation and mineralization rates of different types of plastic objects in a marine environment with existing methods is not straightforward57. We therefore designed a fit-for-purpose laboratory microcosm experiment to investigate biofouling and fragmentation of a variety of plastic objects within a relatively short time span. We determined growth and species composition of biofilms on the plastic items in the microcosm to observe if differences developed depending on the type of material. We hypothesized that weathering and release of small fragments result in the development of pores and crevices in the surface of plastic objects in the microcosm, and when these pores are filled with seawater this can be measured as a decrease of electrical resistance of the plastic objects62,63. Therefore, we tested the effectiveness of electrical resistance of plastic objects as a simple and fast indicator of plastics weathering and fragmentation. We analyzed weight loss to determine fragmentation caused by microplastics generation and/or biodegradation of each plastic type, to test our prediction that plastic products carrying ‘compostable’ labels would fragment faster than conventional thermoplastics in the microcosm over the course of a one-year experiment.

Results

Once the silicon tubes, PET bottles and fleece, PS coffee cups and the PLA materials were placed in the microcosm, they immediately sank to the bottom because of a higher density than seawater. The PU foams, cigarette filters, paper coffee cups and compostable plastic bags with registration numbers 7P0059 and 7P0069 became waterlogged and sank within 4 days. The other plastics, including the HDPE and the LDPE air pouches, latex balloons, PS foams and PP cups remained afloat on the water surface in the microcosm during the entire experiment (Fig. 1). After one year, only one of the six HDPE and two of the three LDPE air pouches had sunk to the bottom of the microcosm.

Pictures of (A) the marine microcosm and (B) added plastic objects with different polymer backbones.

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After 378–383 days in the microcosm the volume fraction (Φ) of water in different plastic items (estimated by triplicate measurements of the capacitance) were 0.79 ± 0.47 (LDPE air pouch), 1.34 ± 0.32 (HDPE air pouch), 1.38 ± 0.39 (PP cup), 1.45 (PET bottle), 2.01 ± 0.11 (PS coffee cup), and 2.18 ± 0.25 (latex balloon). This indicated the uptake of seawater into the plastic objects during incubation in the microcosm.

Electrical resistance (ER) measurements

The ER of different plastic materials in seawater was measured in triplicate within 8 days after incubation, and subsequently at 50 to 150-day intervals during one-year incubation in the microcosm (Table 1). Initially, ER values of the compostable-labelled plastic bags were more than two log-factors lower than those of the non-compostable plastic items. The highest ER values were found for the PET bottles. For all plastic items the ER values measured at 100 Hz, 120 Hz or 1,000 Hz decreased during incubation in the microcosm (Fig. 2). The rate constant at which the ER-values measured at 100 Hz and 120 Hz decreased ranged from 0.0045 day−1 to 0.0165 day−1, depending on the plastic material (Table 1).

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Electrical resistances of latex balloons (upper panel), and compostable trash bags 7P0069 (lower panel), measured at different times during incubation in the microcosm. Electrical resistances were recorded at 100 Hz (□), 110 Hz (∆), or 1,000 Hz (x)0 Hz (o), respectively.

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After 378–390 days in the microcosm, the ER values of PP and PS cups and an LDPE air pouch were measured before and immediately after removing biofilms and washing in demineralized water. We did this in order to remove seawater from the plastics. After this cleaning and washing, the ER values had increased to the range of the initial values when we started the microcosm. This indicated that low ER-values were primarily due to the uptake of seawater by the plastic items.

Fragmentation and weight loss of the plastics

The first effects of microcosm incubation on the plastic material could be observed within the first week of the experiment. First, we observed a change in colour of the compostable trash bags with registration number 7P0069 from translucent light green into opaque white after four days of incubation. In addition, cigarette filters started to lose their paper covers.

Within two months many holes of 1 mm to 10 mm diameter appeared in the 7P0069 compostable trash bags (Fig. 3). Small particles of < 1 mm broke off of the rims of the larger holes. The compostable postal bags with registration number 7P0059 kept their integrity longer, but some holes of about 1 mm were observed after six months in the microcosm (Fig. 3).

Pictures of fragmentation of compostable trash bag 7P0069 after 0, 57 and 183 days from left to right, respectively (upper panels), compostable postal bag 7P0059 after 294 days (lower left panel) and latex balloon after 383 days (lower right panel) in the microcosm.

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After 378 days, loss of small crumbles (< 1 mm) was visible around the neck of the latex balloons (Fig. 3). The compostable PLA food bags and the paper coffee cups however did not show any signs of fragmentation. These materials did however become fragile and easily disintegrated upon touch. Fragmentation of the PLA bags did not result in formation of small crumbs, but rather elongated snippets. The other plastic materials showed no visible fragmentation within one year in the microcosm.

After 378–427 days the plastics were taken from the microcosm and the dry weight of 3 to 12 replicates was determined after removing the biofilms from the surfaces (Fig. 4). The LDPE and HDPE air pouches, the PS coffee cup, the PP cup and the PLA food tray had lost less than one percent of their weight (fragmentation rates < 1% per year). Based on weight loss, the silicon tubes and the PS packaging foam had fragmentation rates of about 1% per year. Fragmentation rates of the PET materials, PUR foam and the latex balloons were between 3 and 5% per year. Higher fragmentation rates, ranging from 7 to 27% per year were found for the compostable bags and the cigarette filters. The fragmentation rate of the paper coffee cups, as natural cellulose polymer reference, was about 8% per year.

Fragmentation rates (% weight loss per year) of objects with different polymer backbones in the marine laboratory microcosm. Red bars indicate polymers with a backbone with single “C–C” carbon bonds, orange a backbone with double “C = C” bonds, purple a siloxane backbone, blue a polyester backbone, and green indicates compostable polymers.

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Microplastics

Qualitative observations with light microscopy revealed that the water samples taken from the bottom of the microcosm tank contained the highest number and variety of particles, both plastic and organic matter. Samples of water taken at 25 cm depth contained relatively low amounts of particles, mainly fibres (Fig. 5). Small plastic fragments were detected mainly in the water from the surface and on the bottom of the microcosm, indicating materials present in the plastic mixture were generally not neutrally buoyant. Numerous fibers and non-plastic debris were observed in the water samples taken from the surface and bottom of the microcosm (Fig. 5). In the reference synthetic seawater, only one particle was detected in a 522 mL sample volume, indicating a very low background level of the incubation seawater compared to the microcosm test.

Images of microplastics and -debris from the microcosm. a Microdebris from the surface water, blue fiber (left), red fiber (middle), blue foil (right). b Red (left) and blue (right) fibers detected at 25 cm depth. c Microdebris from the bottom at 50 cm depth, blue foil (upper left), white foil (upper middle), brown sphere (upper right), unknown white piece (lower left), and unknown particles (lower right).

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Biofouling and microbial populations on plastics

Heavy biofouling occurred within several months, indicating the growth of algae, bacteria and other microorganisms on the surfaces of the plastic materials (Fig. 6). After 378–427 days in the microcosm, the wet and dry weights of the biofilms growing on 2 to 6 replicates of plastic items were determined (Table 2). Determination of the weight of biofilms growing on the cigarette filters, paper coffee cups and PLA food bags was not possible because these materials were too fragile for biofilm collection. The wet weight measurements indicated the presence of thick slimy biofilm layers on all the components added to the microcosm. The dry weight of the biofilms removed from the plastics ranged from 0.068 to 0.459 mg per cm2 of plastic surface exposed to the seawater, which corresponded to biofilm growth rates of 0.063 to 0.441 mg per cm2 per year.

Biofouling of polypropylene cup, after (from left to right) 0, 57, 183 and 390 days in the microcosm, respectively.

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To study the microorganisms in these biofilms, we performed a DNA metabarcoding approach on six samples, in which we focused on the bacterial community (V3-V4 16S rRNA gene sequencing). First, we checked the bacterial community diversity (Shannon–Wiener index) and the richness on the basis of the number of observed operational taxonomic units (OTUs). The lowest number of bacterial OTUs (189) was counted on the PE sample, which also corresponded to the lowest community diversity (2.02). The number of observed OTUs ranged between 307 and 452 for the other samples (Table 3). For the diversity, a mean value of 3.63 ± 0.42 was measured (Table 3). Second, we looked to the community composition on the plastics. Cyanobacteria dominated in all samples, followed by the phyla Proteobacteria, Planctomycetes and in lesser amount the Bacteriodetes (Fig. 7A). Analysis on genus level showed that one specific genus, Leptolyngbya, which was assigned to seven OTUs, dominated the biofilms on all plastic samples and the steel (Fig. 7B). The phyla and genus plots indicated differences in composition between samples, which are also illustrated by a principal coordinates analysis (PCoA) plot (Fig. 8). PE, PP and PS bacterial communities phylogenetically differed most from each other. In comparison, the microbial community of the rope and the steel wall showed the most resemblance.

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Relative abundance of 16S rRNA genes of biofilm samples from the microcosm (A) phylum level (B) genus level. Figures show only those phyla/genera, which represent at least 1% of the total community in at least one sample.

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PCoA plot of the phyla and genus, indicating differences in bacterial population composition between biofilm samples from different objects.

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Discussion

Fragmentation of plastic items can be estimated with a variety of analytical techniques, based on morphological and rheological changes, or on gravimetric, scanning electron microscopy (SEM), spectroscopic or chromatographic analyses56. Many of these methods destroy the plastic samples during analysis and rely on the availability of expensive laboratory equipment. We therefore investigated if electrical resistance (ER) measurements can be applied as a cheap, easy to use, non-destructive alternative. A similar technique, electrochemical impedance spectrometry (EIS), is used to detect pits in paints and coatings, that are too small to be seen microscopically63,64. We used a simple setup to measure the ER of plastic objects submerged in seawater. The decrease of ER-values observed at low AC-frequencies (100 Hz–1,000 Hz) as a function of time is in line with EIS analyses of coatings. Capacitance measurements, and the fact that after washing in demineralized water the ER restored to initial high values, confirm that the ER measurements indicate penetration of water and ions into the plastics. One might hypothesize that this is correlated to the release of plastic particles from the macroplastic objects in the microcosm. The decrease of tensile elongation at break is a common parameter used to asses polymer degradation rates19,33,65. Interestingly, the degradation rate constant of 0.005 day−1, obtained by ER measurements in our laboratory microcosm at 24 °C for LDPE degradation, is in the range of those obtained by Andrady (1993) for different types of control LDPE sheets floating in outdoor sea experiments, using tensile elongation measurements. Degradation rate constants of LDPE sheets floating in sea at Seattle, at mean temperature of 15 °C, were 0.002–0.004 day−1, and at sea near Miami, with mean temperature of 29 °C, they were 0.004–0.008 day−1. Obviously, fragmentation rates obtained in our experiment should not be directly translated to those at sea, since in the laboratory environment temperature, light, water movement, biodiversity, chemical composition of the seawater e.g. due to metal leaching from the stainless-steel vessel are different. Our results suggest that ER-measurements may be a promising cheap and easy technique to readily monitor the initial steps of the degradation of plastics in water. Additional testing of ER-measurements, for example in freshwater and other environments is essential to asses full application possibilities of this method.

Once holes became visible in the plastic objects, ER measurements could no longer be used to measure further degradation. The holes created a direct seawater connection between the electrode inside, and the electrode outside the plastic object, with very low electrical resistance.

As an indicator of fragmentation, we determined weight loss of the plastic objects after 378–427 days in the microcosm. The observation that plastic materials composed of polymers with a carbon–carbon “C–C” backbone, PE, PS and PP, appeared most recalcitrant with a maximum fragmentation rate of 1% per year may be due to the fact that their degradation is initiated through abiotic photolytic oxidation by UV radiation9,39. The spectrum of the fluorescent lamps in our microcosm included UV light, but the rapid and extensive covering with microbial biofilms may have protected the plastic objects from photolytic degradation, resulting in fragmentation and measurable weight loss. In comparison, the latex balloons had fragmentation rates of about 5% per year in the marine microcosm. Natural latex is a complex coagulation of about 90% polyisoprene with carbohydrates, lipids, proteins, alkaloids, organic acids and amino acids66. The latex polymer consists of a backbone of isoprene monomers connected with C=C double bonds. Previous studies indicated that solar radiation as the most important environmental variable for fragmentation of latex films in freshwater and marine outdoor microcosms67. But in addition, latex polymers are known to be degraded by a variety of microorganisms, including marine ones68. Lambert et al. found that latex film exposed in an outdoor microcosm with artificial seawater lost weight at a rate of 50% in 87 days. The big difference to the fragmentation rates of latex material obtained in our microcosm experiment can be related to several factors: (i) a thicker membrane of our latex balloons (0.3 mm) versus the latex films (0.08 mm), (ii) exposure to a lower UV dose in the laboratory microcosm (e.g. biofouling), opposed to the outdoor microcosms, (iii) different composition or cross bonding of the latex polymers, and/or (iv) presence of plasticizers and UV absorbers in our balloons. The abundant presence of latex balloons in marine litter suggests fragmentation rates at least are not higher than rates of littering input69. This underpins the importance of testing degradation of real-life consumer plastic materials under realistic marine conditions. The fragmentation rates of PET and PU objects were between 3 and 5% per year. In PET and PU polymers the monomers are connected through ester bonds, which are susceptible to photo-oxidation, hydrolysis and biodegradation9,25,27. Hydrolysis and biodegradation may have caused further weight loss of PET and PU, than that of carbon–carbon backbone polymers. We observed the greatest weight losses for the cellulose-containing objects and the compostable plastics. Cellulose and cellulose acetate degrading microorganisms are abundant in the marine environment70,71. Moran et al. reported similar rates of weight loss of cellulosic waste in microcosms with ocean water, as we found for the cellulose coffee cups (8% per year) and the cellulose acetate cigarette filters (15% per year). Degradation of the disposable bags, labelled compostable according to the EN 13432 standard, occurred, but still 73% to 93% of their original weight remained after a year in the microcosm. Moreover, weight loss of the PLA food trays (fragmentation rate < 0.3% per year) was insignificant. The difference between weight loss of the PLA bags and the PLA food trays is most likely caused by the different PLA grades used for the production of these items58. This demonstrates that the current standard tests based on composting do not reflect the realistic (bio)degradation of plastic materials in the marine environment.

After a year, we detected numerous microplastic particles in the surface water and on the bottom of the microcosm. The synthetic seawater used to prepare the microcosm contained insignificant amounts of microplastics, which indicates fragmentation as a major cause for weight loss of the plastic objects in the microcosm. We did not quantify the extent to which nano- and microplastics formation, and/or mineralization, respectively, contributed to weight loss of the individual plastic items.

Biofilms on the plastics were visible within a month and increased during the experiment, indicating the presence of active growing microbial communities. The biofilm mass on the plastic materials in the microcosm (0.068–0.459 mg dry weight/cm2) was much lower than that on plastic objects which had been submerged for about one year in the Bay of Bengal, India (28–34 mg dry weight/cm2)34,51. Apparently, microbial growth on plastic objects in our closed microcosm system was less abundant than that on plastics exposed in the sea. The fact that one HDPE and two LDPE air pouches sunk after a year in the microcosm is in line with the observation that biofilms can increase the density of plastic objects, causing them to sink52,72. The impact of such ballasting on microplastics, with high surface area versus volume ratio, could be higher than on macroplastics. Recently, it was suggested that there appears to be a fast removal of plastic fragments smaller than a millimeter from the ocean surface water11,14,73. These experiments are congruent with the assumption that ballasting by microbial biofilms may be one explanation of this observation19,74,75.

Bacterial species richness was lowest in biofilms growing on a PE film and highest on the latex balloon. Possibly, the presence of many different organic biodegradable substrates in natural latex might have enhanced biodiversity on the balloon66. In comparison, the composition of the microbial communities growing on the plastic rope and the stainless-steel wall of the microcosm vessel showed the most resemblance. The observation that microbial populations on PS contained less phototrophs and differed most from those on the other plastics may be explained by the fact that PS items float on the water, and the sample for biofilm analysis was taken from the relatively dark underside. The biofilms on the plastic items in our microcosm appear to be significantly less diverse than those observed on plastic objects obtained from marine environments75,76,77,78. This may reflect the relatively simple and homogeneous setting of our artificial laboratory system. The dominance of phototrophic cyanobacteria was obviously sustained by the daily 12/12 h day/night cycle and the clear seawater, allowing the light to easily reach to the bottom of the microcosm. The fact that about 50% of the 16S rRNA genes detected corresponded to Leptolyngbya is significant, since this genus contains pathogenic species. This emphases the observation of other researchers, that plastic objects can act as habitats for pathogenic microorganisms75,77,79,80.

There is a strong need to understand what happens to plastic litter that is entering our oceans. Monitoring campaigns indicate that the amount of plastic found at the sea surface is not increasing proportionally to the estimated inputs of plastic litter and that there appears to be a short residence time of micro-meter sized particles at the sea surface5,6,11,14,21,22,81,82. It has been suggested that the microplastic particles in the oceans may degrade at faster rates when they become smaller, and that they continue to fragment into more hazardous nanoplastics, which may be too small to detect with current sampling techniques19,83. Recently it was confirmed that particles in the nanometer range are indeed formed during degradation of PS sheets84. We showed that a decrease in ER values may correlate to the formation of sub-microscopic pores, and thus can indicate the formation of nanoparticles. ER measurements provide thus an interesting tool to quantify the initial stage of fragmentation of plastics in seawater.

Biodegradation of compostable plastic objects in our microcosm occurred at much lower rates than in internationally recognized standard composting tests. The main reason may be that during composting tests degradation processes are routinely examined under optimized conditions that are not representative for marine environments. Our study and accumulating research indicates that even plastic materials labelled as compostable, which are meant to reduce accumulation of plastic waste, may not biodegrade and mineralize within an acceptably short timeframe in marine ecosystems85. Solid experimental data on long term degradation of plastic litter should therefore be collected in laboratory micro- and mesocosm systems under conditions that are realistic for the marine environment in order to best inform our understanding of marine plastic degradability.

Materials and methods

Setup of the marine microcosm

A stainless-steel vessel (0.6 m × 0.6 m × 1.2 m) was filled with 350 L artificial seawater (Fig. 1). The synthetic seawater was prepared by adding WesPro sea salt (www.wesdijk.nl) to demineralized water to obtain an electrical conductivity (EC) of 46 mS/cm on a WTW LF 197 EC meter (WTW Wissenschaftlich Technische Werkstätten, Weilheim, Germany). At about 10 cm below the surface, the seawater in the vessel was recirculated at 6.7 L/min with a pump (Velda Aquarius Universal 600, Groenrijk Malkenschoten, Apeldoorn, Netherlands) to create a mild constant water flow. Four fluorescent lamps (30-W, length 90 cm) were installed in the stainless-steel lid of the vessel to expose the plastics to simulated daylight, including UV-a and UV-b. The fluorescent lamps were two Zoo Med Ocean Sun T8 lamps, each generating 70 photons/m2/s, and two Zoomed Repti Sun 5.0 UVB lamps, each generating 60 photons/m2/s on the water surface of the microcosm (www.smulders.nl). Light intensities were measured with a LI-COR LI-192 underwater quantum sensor with 400–700 nm quantum response, connected to a LI-250 A light meter (CaTec b.v., Wateringen, The Netherlands). The microcosm was subjected to a 12:12 h light and dark regime. The temperature of the seawater was 24 ± 1 °C throughout the experiment. The microcosm was closed with a stain-less steel lid, to limit water evaporation and contamination with microplastics from the ambient air.

The microcosm was inoculated with 9 L seawater (conductivity 46 mS/cm) and a variety of plastic materials and stones, collected three days earlier at the North Sea beach at Katwijk aan Zee, The Netherlands. Different types of plastic items with different polymer backbones from household items were collected and added to the marine microcosm, in order to simulate a plastic contaminated marine environment (Fig. 1). The plastics included a selection of conventional thermoplastic and compostable plastic products according to the DIN EN 13,432 standard. Of each material subsamples were stored at 4 °C in the dark. A 5 cm cut was made in the packing material air pouches, to let the air escape before they were added to the microcosm.

Electrical resistance (ER) measurements

Electrical resistance (ER) values (Ohm) of plastic materials were measured with a Voltcraft LCR 300 m (www.conrad.nl). The LCR-meter was connected to two 20 cm long messing electrodes, which were inserted inside Viton rubber tubing and fixed in a butyl rubber stopper. The electrode tips were positioned 1 cm apart from each other. At the tip of the electrodes, 2 cm messing was exposed to the seawater. For ER measurements one electrode tip was inserted in seawater inside a plastic bag, cup or bottle, respectively. The other electrode was positioned at the outside in the seawater of the microcosm. In this way, the ER of the plastics were measured by recording the resistance between the electrodes at different frequencies AC current: 100, 120 and 1,000 Hz, respectively. ER measurements at higher frequencies of 10.000 or 100.000 Hz, respectively, were not consistent and not used for this study. The ER measurements were done in the serial modus (Rs) of the LCR meter. The ER measurements were started 8 days addition after of the plastic objects to the microcosm and at 2 to 5 months’ intervals thereafter. The ER measurements were routinely recorded in triplicate, and the coefficient of variation based on 75 triplicate measurements was 25 ± 2%. The plastics ER values were calculated as follows:

$${ER}_{plastic}= {ER}_{plastic\cdot emerged\cdot in\cdot seawater}-{ER}_{seawater}$$

Volume fraction (Φ) of water

The uptake of water by plastics was estimated by measuring the capacitance (C in nF) immediately after they were added (C start) and just before they were removed (C end) from the microcosm. The volume fraction of water of the plastics (Φ) was subsequently assessed according to the empirical relation of Brasher and Kinsbury86:

$$\Phi =\frac{{\mathrm{log}}\left({\mathrm{C\,end}}/{\mathrm{C\,start}}\right)}{\mathrm{log}80}$$

Values of water fractions are averages ± standard deviations of capacitance measurements obtained at 100, 120 and 1,000 Hz, respectively.

Dry weight analyses and fragmentation rates

The weight of a selection of the plastic objects was measured before and after 378–427 days of incubation in the microcosm (Table 4). After removal from the microcosm, they were first drained for one minute before measurement of the wet weight of the plastics with the biofilms. Subsequently, the biofilms were carefully removed with a nylon brush34. Then the plastics were rinsed with tap water and incubated overnight in demineralized water to remove traces of seawater salts. Finally, the plastics were swept with a tissue and dried on aluminum foil in a stove at 40 °C, typically for 2 to 5 days, until constant weight. Plastics of more than 1 g were weighed on a Mettler PM 4600 balance, others on a Mettler AE 200 balance (Mettler Toledo, Tiel, Netherlands). The weight loss of 0 – 0.1% found for some PE and PP items confirmed that the biofilm removal procedure did not cause significant degradation of these plastic objects. The percentages loss of dry weight of the plastics were calculated subsequently as:

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$$ {\mathrm{Dry}}\cdot {\mathrm{weight}}\cdot {\mathrm{loss}} \left(\%\right)=\frac{{\mathrm{W}}_{0}- {\mathrm{W}}_{\mathrm{t}}}{{\mathrm{W}}_{0}*100}$$

where \({W}_{0}\) is the initial dry weight of a plastic sample before incubation, and \({W}_{t}\) the dry weight determined after “t” days incubation in the microcosm. Fragmentation rates were subsequently expressed as % dry weight loss per year.

Biofilm removal with a toothbrush from the compostable plastic bags, labelled with registration numbers 7P0069, 7P0189 and 7P0204, respectively, was not possible without fragmenting these materials. Therefore, the biofilms from the latter plastics were removed by incubation, with 30% H2O2, overnight at 25 °C, and shaken at 100 rpm. Weight losses of triplicate subsamples of unexposed sheets of 7P0069 and 7P0189 by H2O2 treatment were 1.92 ± 1.0% and 0.094 ± 0.232%, respectively. These values were used as correction factors for dry weight loss analyses of the compostable plastic bags. Weight loss of the cigarette filters was corrected for the loss of their paper covers in the microcosm, which accounted for 49 ± 20% of their mass.

The biofilm material removed from the plastics was suspended in 100 mL autoclaved synthetic seawater and stored it at 4 °C in the dark for further analyses. The dry weight of the biofilms was determined by filtration of 25 mL subsamples of the biofilm suspensions on pre-weighed cellulose acetate filters with a diameter of 47 mm and a pore size of 0.45 µm (www.merckmillipore.com). The filters were dried in a stove at 40 °C for 3 days until constant weight.

Microplastics

Samples were collected at 389 days after plastic addition to the microcosm. For microplastic sampling, 500 mL Erlenmeyer flasks were washed and immediately sealed with aluminum foil. Water samples (approx. 500 mL each) in triplicate were collected from the left, the middle and the right sections of the microcosm. Samples of buoyant microplastics were obtained by holding the opening of the Erlenmeyer flasks about 2 mm below the water surface. Three water samples were collected by opening the flasks 25 cm below the water surface. Samples at the bottom (50 cm depth) were withdrawn with a 100 mL glass syringe (Sanitex Eterna-Matic interchangeable) moving slowly over the bottom of the microcosm. The samples were stored at 4 °C in the dark. Microplastic particles were filtered from the water samples over a Whatman glass filter (diameter 47 mm, pore size 0.2 µm) and then rinsed with 30 mL H2O2 (30%) followed by 30 mL MilliQ® analytical grade water according to Leslie et al.87.

Identification of microbial populations

Five plastic objects and one biofilm sample scraped from the steel wall with a 50 mL Greiner centrifuge tube (VWR International B.V., Amsterdam, Netherlands) were taken 665 days after starting the microcosm. The samples were kept at − 80 °C until DNA extraction and 16S rRNA gene metabarcoding76,78. DNA was extracted using the Powersoil DNA isolation kit (MOBIO Laboratories, Carlsbad, CA) according to the manufacturer’s instructions. The DNA extracts of all samples were stored at − 20 °C until further processing. The extracted DNA was used for bacterial (V3-V4 16S rRNA gene) taxonomic screening through amplicon sequencing using the Illumina technology (Illumina, San Diego, CA, USA). Fragments were amplified and extended with Illumina specific adaptors by using an amplification and dual-index PCR successively (detailed description in De Tender et al.). Each PCR step was followed by a PCR product clean-up using the CleanPCR reagent kit (MAGBIO, Gaithersburg, MD, USA). Quality of the final libraries was checked using the Qiaxcel Advanced with the Qiaxcel DNA High Resolution kit (QIAGEn, Germantown, MD, USA) and concentrations were measured using the quantus double-stranded DNAassay (Promega, Madison, WI, USA). The final barcoded libraries of each sample were diluted to 10 nM and equally pooled. The resulting library was sequenced on an Illumina MiSeq 2 × 300 bp paired-end by Macrogen (Seoul, South Korea), using 30% PhiX DNA as spike-in. Demultiplexing of the amplicon dataset and barcode removal was done by the sequencing provider. The raw sequence data is available in the NCBI Sequence Read Archive under the accession number PRJNA3743322. The sequence read processing was done as described in detail in76.

Statistical analysis

OTU tables of the 16S V3-V4 rRNA gene amplicon sequencing were analyzed using the QIIME software package (v1.9.0)88. Taxonomy was assigned with the script “assign_taxonomy.py” using the uclust method considering maximum 3 database hits, with the silva v119 97% rep set (provided by QIIME) as reference for the bacterial sequences and UNITE v7 (dynamic) for fungal sequences89,90,91. For the analysis of the bacterial populations, both community diversity and composition were studied. To study community diversity, data was rarefied at 20,000 sequences. Based on this rarefied data, the number of observed OTUs and the Shannon–Wiener diversity index were calculated as an estimation of the community’s richness and diversity. Total community composition was analyzed using the multivariate analysis of the specific R package vegan (version 2.3–2)92. The dissimilarity matrix, based on the Bray–Curtis dissimilarity index, was calculated from the OTU table as generated by Usearch for bacterial sequences. This Bray–Curtis dissimilarity matrix was used as input for the Principal Coordinate Analysis (PCoA).

Data availability

All sequence data of this study is available in the NCBI Sequence Read Archive under the accession number PRJNA3743322.

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Источник: [https://torrent-igruha.org/3551-portal.html]

Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005

Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: mmwrq@cdc.gov. Type 508 Accommodation and the title of the report in the subject line of e-mail.

Please note:This report has been corrected and replaces the electronic PDF version that was published on December 30, 2005.

Prepared by

Paul A. Jensen, PhD, Lauren A. Lambert, MPH, Michael F. Iademarco, MD, Renee Ridzon, MD

Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention


The material in this report originated in the National Center for HIV, STD, and TB Prevention, Kevin Fenton, MD, PhD, Director; and the Division of Tuberculosis Elimination, Kenneth G. Castro, MD, Director.

Corresponding preparer: Paul A. Jensen, PhD, Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, 1600 Clifton Rd., NE, MS E-10, Atlanta, GA 30333. Telephone: 404-639-8310; Fax: 404-639-8604; E-mail: pej4@cdc.gov.


Summary

In 1994, CDC published the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994. The guidelines were issued in response to 1) a resurgence of tuberculosis (TB) disease that occurred in the United States in the mid-1980s and early 1990s, 2) the documentation of several high-profile health-care–associated (previously termed "nosocomial") outbreaks related to an increase in the prevalence of TB disease and human immunodeficiency virus (HIV) coinfection, 3) lapses in infection-control practices, 4) delays in the diagnosis and treatment of persons with infectious TB disease, and 5) the appearance and transmission of multidrug-resistant (MDR) TB strains. The 1994 guidelines, which followed statements issued in 1982 and 1990, presented recommendations for TB-infection control based on a risk assessment process that classified health-care facilities according to categories of TB risk, with a corresponding series of administrative, environmental, and respiratory-protection control measures.

The TB infection-control measures recommended by CDC in 1994 were implemented widely in health-care facilities in the United States. The result has been a decrease in the number of TB outbreaks in health-care settings reported to CDC and a reduction in health-care–associated transmission of Mycobacterium tuberculosis to patients and health-care workers (HCWs). Concurrent with this success, mobilization of the nation's TB-control programs succeeded in reversing the upsurge in reported cases of TB disease, and case rates have declined in the subsequent 10 years. Findings indicate that although the 2004 TB rate was the lowest recorded in the United States since national reporting began in 1953, the declines in rates for 2003 (2.3%) and 2004 (3.2%) were the smallest since 1993. In addition, TB infection rates greater than the U.S. average continue to be reported in certain racial/ethnic populations. The threat of MDR TB is decreasing, and the transmission of M. tuberculosis in health-care settings continues to decrease because of implementation of infection-control measures and reductions in community rates of TB.

Given the changes in epidemiology and a request by the Advisory Council for the Elimination of Tuberculosis (ACET) for review and update of the 1994 TB infection-control document, CDC has reassessed the TB infection-control guidelines for health-care settings. This report updates TB control recommendations reflecting shifts in the epidemiology of TB, advances in scientific understanding, and changes in health-care practice that have occurred in the United States during the preceding decade. In the context of diminished risk for health-care–associated transmission of M. tuberculosis, this document places emphasis on actions to maintain momentum and expertise needed to avert another TB resurgence and to eliminate the lingering threat to HCWs, which is mainly from patients or others with unsuspected and undiagnosed infectious TB disease. CDC prepared the current guidelines in consultation with experts in TB, infection control, environmental control, respiratory protection, and occupational health. The new guidelines have been expanded to address a broader concept; health-care–associated settings go beyond the previously defined facilities. The term "health-care setting" includes many types, such as inpatient settings, outpatient settings, TB clinics, settings in correctional facilities in which health care is delivered, settings in which home-based health-care and emergency medical services are provided, and laboratories handling clinical specimens that might contain M. tuberculosis. The term "setting" has been chosen over the term "facility," used in the previous guidelines, to broaden the potential places for which these guidelines apply.

Introduction

Overview

In 1994, CDC published the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Facilities, 1994 (1). The guidelines were issued in response to 1) a resurgence of tuberculosis (TB) disease that occurred in the United States in the mid-1980s and early 1990s, 2) the documentation of multiple high-profile health-care–associated (previously "nosocomial") outbreaks related to an increase in the prevalence of TB disease and human immunodeficiency virus (HIV) coinfection, 3) lapses in infection-control practices, 4) delays in the diagnosis and treatment of persons with infectious TB disease (2,3), and 5) the appearance and transmission of multidrug-resistant (MDR) TB strains (4,5).

The 1994 guidelines, which followed CDC statements issued in 1982 and 1990 (1,6,7), presented recommendations for TB infection control based on a risk assessment process. In this process, health-care facilities were classified according to categories of TB risk,with a corresponding series of environmental and respiratory-protection control measures.

The TB infection-control measures recommended by CDC in 1994 were implemented widely in health-care facilities nationwide (8–15). As a result, a decrease has occurred in 1) the number of TB outbreaks in health-care settings reported to CDC and 2) health-care–associated transmission of M. tuberculosis to patients and health-care workers (HCWs) (9,16–23). Concurrent with this success, mobilization of the nation's TB-control programs succeeded in reversing the upsurge in reported cases of TB disease, and case rates have declined in the subsequent 10 years (4,5). Findings indicate that although the 2004 TB rate was the lowest recorded in the United States since national reporting began in 1953, the declines in rates for 2003 (2.3%) and 2004 (3.2%) were the lowest since 1993. In addition, TB rates higher than the U.S. average continue to be reported in certain racial/ethnic populations (24). The threat of MDR TB is decreasing, and the transmission of M. tuberculosis in health-care settings continues to decrease because of implementation of infection-control measures and reductions in community rates of TB (4,5,25).

Despite the general decline in TB rates in recent years, a marked geographic variation in TB case rates persists, which means that HCWs in different areas face different risks (10). In 2004, case rates varied per 100,000 population: 1.0 in Wyoming, 7.1 in New York, 8.3 in California, and 14.6 in the District of Columbia (26). In addition, despite the progress in the United States, the 2004 rate of 4.9 per 100,000 population remained higher than the 2000 goal of 3.5. This goal was established as part of the national strategic plan for TB elimination; the final goal is <1 case per 1,000,000 population by 2010 (4,5,26).

Given the changes in epidemiology and a request by the Advisory Council for the Elimination of Tuberculosis (ACET) for review and updating of the 1994 TB infection-control document, CDC has reassessed the TB infection-control guidelines for health-care settings. This report updates TB-control recommendations, reflecting shifts in the epidemiology of TB (27), advances in scientific understanding, and changes in health-care practice that have occurred in the United States in the previous decade (28). In the context of diminished risk for health-care–associated transmission of M. tuberculosis, this report emphasizes actions to maintain momentum and expertise needed to avert another TB resurgence and eliminate the lingering threat to HCWs, which is primarily from patients or other persons with unsuspected and undiagnosed infectious TB disease.

CDC prepared the guidelines in this report in consultation with experts in TB, infection control, environmental control, respiratory protection, and occupational health. This report replaces all previous CDC guidelines for TB infection control in health-care settings (1,6,7). Primary references citing evidence-based science are used in this report to support explanatory material and recommendations. Review articles, which include primary references, are used for editorial style and brevity.

The following changes differentiate this report from previous guidelines:

  • The risk assessment process includes the assessment of additional aspects of infection control.
  • The term "tuberculin skin tests" (TSTs) is used instead of purified protein derivative (PPD).
  • The whole-blood interferon gamma release assay (IGRA), QuantiFERON(r)-TB Gold test (QFT-G) (Cellestis Limited, Carnegie, Victoria, Australia), is a Food and Drug Administration (FDA)–approved in vitro cytokine-based assay for cell-mediated immune reactivity to M. tuberculosis and might be used instead of TST in TB screening programs for HCWs. This IGRA is an example of a blood assay for M. tuberculosis (BAMT).
  • The frequency of TB screening for HCWs has been decreased in various settings, and the criteria for determination of screening frequency have been changed.
  • The scope of settings in which the guidelines apply has been broadened to include laboratories and additional outpatient and nontraditional facility-based settings.
  • Criteria for serial testing for M. tuberculosis infection of HCWs are more clearly defined. In certain settings, this change will decrease the number of HCWs who need serial TB screening.
  • These recommendations usually apply to an entire health-care setting rather than areas within a setting.
  • New terms, airborne infection precautions (airborne precautions) and airborne infection isolation room (AII room), are introduced.
  • Recommendations for annual respirator training, initial respirator fit testing, and periodic respirator fit testing have been added.
  • The evidence of the need for respirator fit testing is summarized.
  • Information on ultraviolet germicidal irradiation (UVGI) and room-air recirculation units has been expanded.
  • Additional information regarding MDR TB and HIV infection has been included.

In accordance with relevant local, state, and federal laws, implementation of all recommendations must safeguard the confidentiality and civil rights of all HCWs and patients who have been infected with M. tuberculosis and who developTB disease.

The 1994 CDC guidelines were aimed primarily at hospital-based facilities, which frequently refer to a physical building or set of buildings. The 2005 guidelines have been expanded to address a broader concept. Setting has been chosen instead of "facility" to expand the scope of potential places for which these guidelines apply (Appendix A). "Setting" is used to describe any relationship (physical or organizational) in which HCWs might share air space with persons with TB disease or in which HCWs might be in contact with clinical specimens. Various setting types might be present in a single facility. Health-care settings include inpatient settings, outpatient settings, and nontraditional facility-based settings.

  • Inpatient settings include patient rooms, emergency departments (EDs), intensive care units (ICUs), surgical suites, laboratories, laboratory procedure areas, bronchoscopy suites, sputum induction or inhalation therapy rooms, autopsy suites, and embalming rooms.
  • Outpatient settings include TB treatment facilities, medical offices, ambulatory-care settings, dialysis units, and dental-care settings.
  • Nontraditional facility-based settings include emergency medical service (EMS), medical settings in correctional facilities (e.g., prisons, jails, and detention centers), home-based health-care and outreach settings, long-term–care settings (e.g., hospices, skilled nursing facilities), and homeless shelters. Other settings in which suspected and confirmed TB patients might be encountered might include cafeterias, general stores, kitchens, laundry areas, maintenance shops, pharmacies, and law enforcement settings.

HCWs Who Should Be Included in a TB Surveillance Program

HCWs refer to all paid and unpaid persons working in health-care settings who have the potential for exposure to M. tuberculosis through air space shared with persons with infectious TB disease. Part time, temporary, contract, and full-time HCWs should be included in TB screening programs. All HCWs who have duties that involve face-to-face contact with patients with suspected or confirmed TB disease (including transport staff) should be included in a TB screening program.

The following are HCWs who might be included in a TB screening program:

  • Administrators or managers
  • Bronchoscopy staff
  • Chaplains
  • Clerical staff
  • Computer programmers
  • Construction staff
  • Correctional officers
  • Craft or repair staff
  • Dental staff
  • Dietician or dietary staff
  • ED staff
  • Engineers
  • Food service staff
  • Health aides
  • Health and safety staff
  • Housekeeping or custodial staff
  • Homeless shelter staff
  • Infection-control staff
  • ICU staff
  • Janitorial staff
  • Laboratory staff
  • Maintenance staff
  • Morgue staff
  • Nurses
  • Outreach staff
  • Pathology laboratory staff
  • Patient transport staff, including EMS
  • Pediatric staff
  • Pharmacists
  • Phlebotomists
  • Physical and occupational therapists
  • Physicians (assistant, attending, fellow, resident, or intern), including
    — anesthesiologists
    — pathologists
    — psychiatrists
    — psychologists
  • Public health educators or teachers
  • Public safety staff
  • Radiology staff
  • Respiratory therapists
  • Scientists
  • Social workers
  • Students (e.g., medical, nursing, technicians, and allied health)
  • Technicians (e.g., health, laboratory, radiology, and animal)
  • Veterinarians
  • Volunteers

In addition, HCWs who perform any of the following activities should also be included in the TB screening program.

  • entering patient rooms or treatment rooms whether or not a patient is present;
  • participating in aerosol-generating or aerosol-producing procedures (e.g., bronchoscopy, sputum induction, and administration of aerosolized medications) (29);
  • participating in suspected or confirmed M. tuberculosis specimen processing; or
  • installing, maintaining, or replacing environmental controls in areas in which persons with TB disease are encountered.

Pathogenesis, Epidemiology, and Transmission of M. tuberculosis

M. tuberculosis is carried in airborne particles called droplet nuclei that can be generated when persons who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing (30,31). The particles are approximately 1–5 µm; normal air currents can keep them airborne for prolonged periods and spread them throughout a room or building (32). M. tuberculosis is usually transmitted only through air, not by surface contact. After the droplet nuclei are in the alveoli, local infection might be established, followed by dissemination to draining lymphatics and hematogenous spread throughout the body (33). Infection occurs when a susceptible person inhales droplet nuclei containing M. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli. Persons with TB pleural effusions might also have concurrent unsuspected pulmonary or laryngeal TB disease.

Usually within 2–12 weeks after initial infection with M. tuberculosis, the immune response limits additional multiplication of the tubercle bacilli, and immunologic test results for M. tuberculosis infection become positive. However, certain bacilli remain in the body and are viable for multiple years. This condition is referred to as latent tuberculosis infection (LTBI). Persons with LTBI are asymptomatic (they have no symptoms of TB disease) and are not infectious.

In the United States, LTBI has been diagnosed traditionally based on a PPD-based TST result after TB disease has been excluded. In vitro cytokine-based immunoassays for the detection of M. tuberculosis infection have been the focus of intense research and development. One such blood assay for M. tuberculosis (or BAMT) is an IGRA, the QuantiFERON(r)-TB test (QFT), and the subsequently developed version, QFT-G. The QFT-G measures cell-mediated immune responses to peptides from two M. tuberculosis proteins that are not present in any Bacille Calmette-Guérin (BCG) vaccine strain and that are absent from the majority of nontuberculous mycobacteria (NTM), also known as mycobacteria other than TB (MOTT). QFT-G was approved by FDA in 2005 and is an available option for detecting M. tuberculosis infection. CDC recommendations for the United States regarding QFT and QFT-G have been published (34,35). Because this field is rapidly evolving, in this report, BAMT will be used generically to refer to the test currently available in the United States.

Additional cytokine-based immunoassays are under development and might be useful in the diagnosis of M. tuberculosis infection. Future FDA-licensed products in combination with CDC-issued recommendations might provide additional diagnostic alternatives. The latest CDC recommendations for guidance on diagnostic use of these and related technologies are available at http://www.cdc.gov/nchstp/tb/pubs/mmwr/html/Maj_guide/Diagnosis.htm.

Typically, approximately 5%–10% of persons who become infected with M. tuberculosis and who are not treated for LTBI will develop TB disease during their lifetimes (1). The risk for progression of LTBI to TB disease is highest during the first several years after infection (36–38).

Persons at Highest Risk for Exposure to and Infection with M. tuberculosis

Characteristics of persons exposed to M. tuberculosis that might affect the risk for infection are not as well defined. The probability that a person who is exposed to M. tuberculosis will become infected depends primarily on the concentration of infectious droplet nuclei in the air and the duration of exposure to a person with infectious TB disease. The closer the proximity and the longer the duration of exposure, the higher the risk is for being infected.

Close contacts are persons who share the same air space in a household or other enclosed environment for a prolonged period (days or weeks, not minutes or hours) with a person with pulmonary TB disease (39). A suspect TB patient is a person in whom a diagnosis of TB disease is being considered, whether or not antituberculosis treatment has been started. Persons generally should not remain a suspect TB patient for >3 months (30,39).

In addition to close contacts, the following persons are also at higher risk for exposure to and infection with M. tuberculosis. Persons listed who are also close contacts should be top priority.

  • Foreign-born persons, including children, especially those who have arrived to the United States within 5 years after moving from geographic areas with a high incidence of TB disease (e.g., Africa, Asia, Eastern Europe, Latin America, and Russia) or who frequently travel to countries with a high prevalence of TB disease.
  • Residents and employees of congregate settings that are high risk (e.g., correctional facilities, long-term–care facilities [LTCFs], and homeless shelters).
  • HCWs who serve patients who are at high risk.
  • HCWs with unprotected exposure to a patient with TB disease before the identification and correct airborne precautions of the patient.
  • Certain populations who are medically underserved and who have low income, as defined locally.
  • Populations at high risk who are defined locally as having an increased incidence of TB disease.
  • Infants, children, and adolescents exposed to adults in high-risk categories.

Persons Whose Condition is at High Risk for Progression From LTBI to TB Disease

The following persons are at high risk for progressing from LTBI to TB disease:

  • persons infected with HIV;
  • persons infected with M. tuberculosis within the previous 2 years;
  • infants and children aged <4 years;
  • persons with any of the following clinical conditions or other immunocompromising conditions
    — silicosis,
    — diabetes mellitus,
    — chronic renal failure,
    — certain hematologic disorders (leukemias and lymphomas),
    — other specific malignancies (e.g., carcinoma of the head, neck, or lung),
    — body weight ≥10% below ideal body weight,
    — prolonged corticosteroid use,
    — other immunosuppressive treatments (including tumor necrosis factor-alpha [TNF-α] antagonists),
    — organ transplant,
    — end-stage renal disease (ESRD), and
    — intestinal bypass or gastrectomy; and
  • persons with a history of untreated or inadequately treated TB disease, including persons with chest radiograph findings consistent with previous TB disease.

Persons who use tobacco or alcohol (40,41), illegal drugs, including injection drugs and crack cocaine (42–47), might also be at increased risk for infection and disease. However, because of multiple other potential risk factors that commonly occur among such persons, use of these substances has been difficult to identify as separate risk factors.

HIV infection is the greatest risk factor for progression from LTBI to TB disease (22,39,48,49). Therefore, voluntary HIV counseling, testing, and referral should be routinely offered to all persons at risk for LTBI (1,50,51). Health-care settings should be particularly aware of the need for preventing transmission of M. tuberculosis in settings in which persons infected with HIV might be encountered or might work (52).

All HCWs should be informed regarding the risk for developing TB disease after being infected with M. tuberculosis (1). However, the rate of TB disease among persons who are HIV-infected and untreated for LTBI in the United States is substantially higher, ranging from 1.7–7.9 TB cases per 100 person-years (53). Persons infected with HIV who are already severely immunocompromised and who become newly infected with M. tuberculosis have a greater risk for developing TB disease, compared with newly infected persons without HIV infection (39,53–57).

The percentage of patients with TB disease who are HIV-infected is decreasing in the United States because of improved infection-control practices and better diagnosis and treatment of both HIV infection and TB. With increased voluntary HIV counseling and testing and the increasing use of treatment for LTBI, TB disease will probably continue to decrease among HIV-infected persons in the United States (58). Because the risk for disease is particularly high among HIV-infected persons with M. tuberculosis infection, HIV-infected contacts of persons with infectious pulmonary or laryngeal TB disease must be evaluated for M. tuberculosis infection, including the exclusion of TB disease, as soon as possible after learning of exposure (39,49,53).

Vaccination with BCG probably does not affect the risk for infection after exposure, but it might decrease the risk for progression from infection with M. tuberculosis to TB disease, preventing the development of miliary and meningeal disease in infants and young children (59,60). Although HIV infection increases the likelihood of progression from LTBI to TB disease (39,49), whether HIV infection increases the risk for becoming infected if exposed to M. tuberculosis is not known.

Characteristics of a Patient with TB Disease That Increase the Risk for Infectiousness

The following characteristics exist in a patient with TB disease that increases the risk for infectiousness:

  • presence of cough;
  • cavitation on chest radiograph;
  • positive acid-fast bacilli (AFB) sputum smear result;
  • respiratory tract disease with involvement of the larynx (substantially infectious);
  • respiratory tract disease with involvement of the lung or pleura (exclusively pleural involvement is less infectious);
  • failure to cover the mouth and nose when coughing;
  • incorrect, lack of, or short duration of antituberculosis treatment; and
  • undergoing cough-inducing or aerosol-generating procedures (e.g., bronchoscopy, sputum induction, and administration of aerosolized medications) (29).

Environmental Factors That Increase the Risk for Probability of Transmission of M. tuberculosis

The probability of the risk for transmission of M. tuberculosis is increased as a result of various environmental factors.

  • Exposure to TB in small, enclosed spaces.
  • Inadequate local or general ventilation that results in insufficient dilution or removal of infectious droplet nuclei.
  • Recirculation of air containing infectious droplet nuclei.
  • Inadequate cleaning and disinfection of medical equipment.
  • Improper procedures for handling specimens.

Risk for Health-Care–Associated Transmission of M. tuberculosis

Transmission of M. tuberculosis is a risk in health-care settings (57,61–79). The magnitude of the risk varies by setting, occupational group, prevalence of TB in the community, patient population, and effectiveness of TB infection-control measures. Health-care–associated transmission of M. tuberculosis has been linked to close contact with persons with TB disease during aerosol-generating or aerosol-producing procedures, including bronchoscopy (29,63,80–82), endotracheal intubation, suctioning (66), other respiratory procedures (8,9,83–86), open abscess irrigation (69,83), autopsy (71,72,77), sputum induction, and aerosol treatments that induce coughing (87–90).

Of the reported TB outbreaks in health-care settings, multiple outbreaks involved transmission of MDR TB strains to both patients and HCWs (56,57,70,87,91–94). The majority of the patients and certain HCWs were HIV-infected, and progression to TB and MDR TB disease was rapid. Factors contributing to these outbreaks included delayed diagnosis of TB disease, delayed initiation and inadequate airborne precautions, lapses in AII practices and precautions for cough-inducing and aerosol-generating procedures, and lack of adequate respiratory protection. Multiple studies suggest that the decline in health-care–associated transmission observed in specific institutions is associated with the rigorous implementation of infection-control measures (11,12,18–20,23,95–97). Because various interventions were implemented simultaneously, the effectiveness of each intervention could not be determined.

After the release of the 1994 CDC infection-control guidelines, increased implementation of recommended infection-control measures occurred and was documented in multiple national surveys (13,15,98,99). In a survey of approximately 1,000 hospitals, a TST program was present in nearly all sites, and 70% reported having an AII room (13). Other surveys have documented improvement in the proportion of AII rooms meeting CDC criteria and proportion of HCWs using CDC-recommended respiratory protection and receiving serial TST (15,98). A survey of New York City hospitals with high caseloads of TB disease indicated 1) a decrease in the time that patients with TB disease spent in EDs before being transferred to a hospital room, 2) an increase in the proportion of patients initially placed in AII rooms, 3) an increase in the proportion of patients started on recommended antituberculosis treatment and reported to the local or state health department, and 4) an increase in the use of recommended respiratory protection and environmental controls (99). Reports of increased implementation of recommended TB infection controls combined with decreased reports of outbreaks of TB disease in health-care settings suggest that the recommended controls are effective in reducing and preventing health-care–associated transmission of M. tuberculosis (28).

Less information is available regarding the implementation of CDC-recommended TB infection-control measures in settings other than hospitals. One study identified major barriers to implementation that contribute to the costs of a TST program in health departments and hospitals, including personnel costs, HCWs' time off from work for TST administration and reading, and training and education of HCWs (100). Outbreaks have occurred in outpatient settings (i.e., private physicians' offices and pediatric settings) where the guidelines were not followed (101–103). CDC-recommended TB infection-control measures are implemented in correctional facilities, and certain variations might relate to resources, expertise, and oversight (104–106).

Fundamentals of TB Infection Control

One of the most critical risks for health-care–associated transmission of M. tuberculosis in health-care settings is from patients with unrecognized TB disease who are not promptly handled with appropriate airborne precautions (56,57,93,104) or who are moved from an AII room too soon (e.g., patients with unrecognized TB and MDR TB) (94). In the United States, the problem of MDR TB, which was amplified by health-care–associated transmission, has been substantially reduced by the use of standardized antituberculosis treatment regimens in the initial phase of therapy, rapid drug-susceptibility testing, directly observed therapy (DOT), and improved infection-control practices (1). DOT is an adherence-enhancing strategy in which an HCW or other specially trained health professional watches a patient swallow each dose of medication and records the dates that the administration was observed. DOT is the standard of care for all patients with TB disease and should be used for all doses during the course of therapy for TB disease and for LTBI whenever feasible.

All health-care settings need a TB infection-control program designed to ensure prompt detection, airborne precautions, and treatment of persons who have suspected or confirmed TB disease (or prompt referral of persons who have suspected TB disease for settings in which persons with TB disease are not expected to be encountered). Such a program is based on a three-level hierarchy of controls, including administrative, environmental, and respiratory protection (86,107,108).

Administrative Controls

The first and most important level of TB controls is the use of administrative measures to reduce the risk for exposure to persons who might have TB disease. Administrative controls consist of the following activities:

  • assigning responsibility for TB infection control in the setting;
  • conducting a TB risk assessment of the setting;
  • developing and instituting a written TB infection-control plan to ensure prompt detection, airborne precautions, and treatment of persons who have suspected or confirmed TB disease;
  • ensuring the timely availability of recommended laboratory processing, testing, and reporting of results to the ordering physician and infection-control team;
  • implementing effective work practices for the management of patients with suspected or confirmed TB disease;
  • ensuring proper cleaning and sterilization or disinfection of potentially contaminated equipment (usually endoscopes);
  • training and educating HCWs regarding TB, with specific focus on prevention, transmission, and symptoms;
  • screening and evaluating HCWs who are at risk for TB disease or who might be exposed to M. tuberculosis (i.e., TB screening program);
  • applying epidemiologic-based prevention principles, including the use of setting-related infection-control data;
  • using appropriate signage advising respiratory hygiene and cough etiquette; and
  • coordinating efforts with the local or state health department.

HCWs with TB disease should be allowed to return to work when they 1) have had three negative AFB sputum smear results (109–112) collected 8–24 hours apart, with at least one being an early morning specimen because respiratory secretions pool overnight; and 2) have responded to antituberculosis treatment that will probably be effective based on susceptibility results. In addition, HCWs with TB disease should be allowed to return to work when a physician knowledgeable and experienced in managing TB disease determines that HCWs are noninfectious (see Treatment Procedures for LTBI and TB Disease). Consideration should also be given to the type of setting and the potential risk to patients (e.g., general medical office versus HIV clinic) (see Supplements, Estimating the Infectiousness of a TB Patient; Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease).

Environmental Controls

The second level of the hierarchy is the use of environmental controls to prevent the spread and reduce the concentration of infectious droplet nuclei in ambient air.

Primary environmental controls consist of controlling the source of infection by using local exhaust ventilation (e.g., hoods, tents, or booths) and diluting and removing contaminated air by using general ventilation.

Secondary environmental controls consist of controlling the airflow to prevent contamination of air in areas adjacent to the source (AII rooms) and cleaning the air by using high efficiency particulate air (HEPA) filtration or UVGI.

Respiratory-Protection Controls

The first two control levels minimize the number of areas in which exposure to M. tuberculosis might occur and, therefore, minimize the number of persons exposed. These control levels also reduce, but do not eliminate, the risk for exposure in the limited areas in which exposure can still occur. Because persons entering these areas might be exposed to M. tuberculosis, the third level of the hierarchy is the use of respiratory protective equipment in situations that pose a high risk for exposure. Use of respiratory protection can further reduce risk for exposure of HCWs to infectious droplet nuclei that have been expelled into the air from a patient with infectious TB disease (see Respiratory Protection). The following measures can be taken to reduce the risk for exposure:

  • implementing a respiratory-protection program,
  • training HCWs on respiratory protection, and
  • training patients on respiratory hygiene and cough etiquette procedures.

Relevance to Biologic Terrorism Preparedness

MDR M. tuberculosis is classified as a category C agent of biologic terrorism (113). Implementation of the TB infection-control guidelines described in this document is essential for preventing and controlling transmission of M. tuberculosis in health-care settings. Additional information is at http://www.bt.cdc.gov and http://www.idsociety.org/bt/toc.htm (114).

Recommendations for Preventing Transmission of M. tuberculosis in Health-Care Settings

TB Infection-Control Program

Every health-care setting should have a TB infection-control plan that is part of an overall infection-control program. The specific details of the TB infection-control program will differ, depending on whether patients with suspected or confirmed TB disease might be encountered in the setting or whether patients with suspected or confirmed TB disease will be transferred to another health-care setting. Administrators making this distinction should obtain medical and epidemiologic consultation from state and local health departments.

TB Infection-Control Program for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

The TB infection-control program should consist of administrative controls, environmental controls, and a respiratory-protection program. Every setting in which services are provided to persons who have suspected or confirmed infectious TB disease, including laboratories and nontraditional facility-based settings, should have a TB infection-control plan. The following steps should be taken to establish a TB infection-control program in these settings:

  1. Assign supervisory responsibility for the TB infection-control program to a designated person or group with expertise in LTBI and TB disease, infection control, occupational health, environmental controls, and respiratory protection. Give the supervisor or supervisory body the support and authority to conduct a TB risk assessment, implement and enforce TB infection-control policies, and ensure recommended training and education of HCWs.
    — Train the persons responsible for implementing and enforcing the TB infection-control program.
    — Designate one person with a back-up as the TB resource person to whom questions and problems should be addressed, if supervisory responsibility is assigned to a committee.
  2. Develop a written TB infection-control plan that outlines a protocol for the prompt recognition and initiation of airborne precautions of persons with suspected or confirmed TB disease, and update it annually.
  3. Conduct a problem evaluation (see Problem Evaluation) if a case of suspected or confirmed TB disease is not promptly recognized and appropriate airborne precautions not initiated, or if administrative, environmental, or respiratory-protection controls fail.
  4. Perform a contact investigation in collaboration with the local or state health department if health-care–associated transmission of M. tuberculosis is suspected (115). Implement and monitor corrective action.
  5. Collaborate with the local or state health department to develop administrative controls consisting of the risk assessment, the written TB infection-control plan, management of patients with suspected or confirmed TB disease, training and education of HCWs, screening and evaluation of HCWs, problem evaluation, and coordination.
  6. Implement and maintain environmental controls, including AII room(s) (see Environmental Controls).
  7. Implement a respiratory-protection program.
  8. Perform ongoing training and education of HCWs (see Suggested Components of an Initial TB Training and Education Program for HCWs).
  9. Create a plan for accepting patients who have suspected or confirmed TB disease if they are transferred from another setting.

TB Infection-Control Program for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

Settings in which TB patients might stay before transfer should still have a TB infection-control program in place consisting of administrative, environmental, and respiratory-protection controls. The following steps should be taken to establish a TB infection-control program in these settings:

  1. Assign responsibility for the TB infection-control program to appropriate personnel.
  2. Develop a written TB infection-control plan that outlines a protocol for the prompt recognition and transfer of persons who have suspected or confirmed TB disease to another health-care setting. The plan should indicate procedures to follow to separate persons with suspected or confirmed infectious TB disease from other persons in the setting until the time of transfer. Evaluate the plan annually, if possible, to ensure that the setting remains one in which persons who have suspected or confirmed TB disease are not encountered and that they are promptly transferred.
  3. Conduct a problem evaluation (see Problem Evaluation) if a case of suspected or confirmed TB disease is not promptly recognized, separated from others, and transferred.
  4. Perform an investigation in collaboration with the local or state health department if health-care–associated transmission of M. tuberculosis is suspected.
  5. Collaborate with the local or state health department to develop administrative controls consisting of the risk assessment and the written TB infection-control plan.

TB Risk Assessment

Every health-care setting should conduct initial and ongoing evaluations of the risk for transmission of M. tuberculosis, regardless of whether or not patients with suspected or confirmed TB disease are expected to be encountered in the setting. The TB risk assessment determines the types of administrative, environmental, and respiratory-protection controls needed for a setting and serves as an ongoing evaluation tool of the quality of TB infection control and for the identification of needed improvements in infection-control measures. Part of the risk assessment is similar to a program review that is conducted by the local TB-control program (42). The TB Risk Assessment Worksheet (Appendix B) can be used as a guide for conducting a risk assessment. This worksheet frequently does not specify values for acceptable performance indicators because of the lack of scientific data.

TB Risk Assessment for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

The initial and ongoing risk assessment for these settings should consist of the following steps:

  1. Review the community profile of TB disease in collaboration with the state or local health department.
  2. Consult the local or state TB-control program to obtain epidemiologic surveillance data necessary to conduct a TB risk assessment for the health-care setting.
  3. Review the number of patients with suspected or confirmed TB disease who have been encountered in the setting during at least the previous 5 years.
  4. Determine if persons with unrecognized TB disease have been admitted to or were encountered in the setting during the previous 5 years.
  5. Determine which HCWs need to be included in a TB screening program and the frequency of screening (based on risk classification) (Appendix C).
  6. Ensure the prompt recognition and evaluation of suspected episodes of health-care–associated transmission of M. tuberculosis.
  7. Identify areas in the setting with an increased risk for health-care–associated transmission of M. tuberculosis, and target them for improved TB infection controls.
  8. Assess the number of AII rooms needed for the setting. The risk classification for the setting should help to make this determination, depending on the number of TB patients examined. At least one AII room is needed for settings in which TB patients stay while they are being treated, and additional AII rooms might be needed, depending on the magnitude of patient-days of cases of suspected or confirmed TB disease. Additional AII rooms might be considered if options are limited for transferring patients with suspected or confirmed TB disease to other settings with AII rooms.
  9. Determine the types of environmental controls needed other than AII rooms (see TB Airborne Precautions).
  10. Determine which HCWs need to be included in the respiratory-protection program.
  11. Conduct periodic reassessments (annually, if possible) to ensure
    — proper implementation of the TB infection-control plan,
    — prompt detection and evaluation of suspected TB cases,
    — prompt initiation of airborne precautions of suspected infectious TB cases,
    — recommended medical management of patients with suspected or confirmed TB disease (31),
    — functional environmental controls,
    — implementation of the respiratory-protection program, and
    — ongoing HCW training and education regarding TB.
  12. Recognize and correct lapses in infection control.

TB Risk Assessment for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

The initial and ongoing risk assessment for these settings should consist of the following steps:

  1. Review the community profile of TB disease in collaboration with the local or state health department.
  2. Consult the local or state TB-control program to obtain epidemiologic surveillance data necessary to conduct a TB risk assessment for the health-care setting.
  3. Determine if persons with unrecognized TB disease were encountered in the setting during the previous 5 years.
  4. Determine if any HCWs need to be included in the TB screening program.
  5. Determine the types of environmental controls that are currently in place, and determine if any are needed in the setting (Appendices A and D).
  6. Document procedures that ensure the prompt recognition and evaluation of suspected episodes of health-care–associated transmission of M. tuberculosis.
  7. Conduct periodic reassessments (annually, if possible) to ensure 1) proper implementation of the TB infection-control plan; 2) prompt detection and evaluation of suspected TB cases; 3) prompt initiation of airborne precautions of suspected infectious TB cases before transfer; 4) prompt transfer of suspected infectious TB cases; 5) proper functioning of environmental controls, as applicable; and 6) ongoing TB training and education for HCWs.
  8. Recognize and correct lapses in infection control.

Use of Risk Classification to Determine Need for TB Screening and Frequency of Screening HCWs

Risk classification should be used as part of the risk assessment to determine the need for a TB screening program for HCWs and the frequency of screening (Appendix C). A risk classification usually should be determined for the entire setting. However, in certain settings (e.g., health-care organizations that encompass multiple sites or types of services), specific areas defined by geography, functional units, patient population, job type, or location within the setting might have separate risk classifications. Examples of assigning risk classifications have been provided (see Risk Classification Examples).

TB Screening Risk Classifications

The three TB screening risk classifications are low risk, medium risk, and potential ongoing transmission. The classification of low risk should be applied to settings in which persons with TB disease are not expected to be encountered, and, therefore, exposure to M. tuberculosis is unlikely. This classification should also be applied to HCWs who will never be exposed to persons with TB disease or to clinical specimens that might contain M. tuberculosis.

The classification of medium risk should be applied to settings in which the risk assessment has determined that HCWs will or will possibly be exposed to persons with TB disease or to clinical specimens that might contain M. tuberculosis.

The classification of potential ongoing transmission should be temporarily applied to any setting (or group of HCWs) if evidence suggestive of person-to-person (e.g., patient-to-patient, patient-to-HCW, HCW-to-patient, or HCW-to-HCW) transmission of M. tuberculosis has occurred in the setting during the preceding year. Evidence of person-to-person transmission of M. tuberculosis includes 1) clusters of TST or BAMT conversions, 2) HCW with confirmed TB disease, 3) increased rates of TST or BAMT conversions, 4) unrecognized TB disease in patients or HCWs, or 5) recognition of an identical strain of M. tuberculosis in patients or HCWs with TB disease identified by deoxyribonucleic acid (DNA) fingerprinting.

If uncertainty exists regarding whether to classify a setting as low risk or medium risk, the setting typically should be classified as medium risk.

TB Screening Procedures for Settings (or HCWs) Classified as Low Risk

  • All HCWs should receive baseline TB screening upon hire, using two-step TST or a single BAMT to test for infection with M. tuberculosis.
  • After baseline testing for infection with M. tuberculosis, additional TB screening is not necessary unless an exposure to M. tuberculosis occurs.
  • HCWs with a baseline positive or newly positive test result for M. tuberculosis infection (i.e., TST or BAMT) or documentation of treatment for LTBI or TB disease should receive one chest radiograph result to exclude TB disease (or an interpretable copy within a reasonable time frame, such as 6 months). Repeat radiographs are not needed unless symptoms or signs of TB disease develop or unless recommended by a clinician (39,116).

TB Screening Procedures for Settings (or HCWs) Classified as Medium Risk

  • All HCWs should receive baseline TB screening upon hire, using two-step TST or a single BAMT to test for infection with M. tuberculosis.
  • After baseline testing for infection with M. tuberculosis, HCWs should receive TB screening annually (i.e., symptom screen for all HCWs and testing for infection with M. tuberculosis for HCWs with baseline negative test results).
  • HCWs with a baseline positive or newly positive test result for M. tuberculosis infection or documentation of previous treatment for LTBI or TB disease should receive one chest radiograph result to exclude TB disease. Instead of participating in serial testing, HCWs should receive a symptom screen annually. This screen should be accomplished by educating the HCW about symptoms of TB disease and instructing the HCW to report any such symptoms immediately to the occupational health unit. Treatment for LTBI should be considered in accordance with CDC guidelines (39).

TB Screening Procedures for Settings (or HCWs) Classified as Potential Ongoing Transmission

  • Testing for infection with M. tuberculosis might need to be performed every 8–10 weeks until lapses in infection control have been corrected, and no additional evidence of ongoing transmission is apparent.
  • The classification of potential ongoing transmission should be used as a temporary classification only. It warrants immediate investigation and corrective steps. After a determination that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Settings Adopting BAMT for Use in TB Screening

Settings that use TST as part of TB screening and want to adopt BAMT can do so directly (without any overlapping TST) or in conjunction with a period of evaluation (e.g., 1 or 2 years) during which time both TST and BAMT are used. Baseline testing for BAMT would be established as a single step test. As with the TST, BAMT results should be recorded in detail. The details should include date of blood draw, result in specific units, and the laboratory interpretation (positive, negative, or indeterminate—and the concentration of cytokine measured, for example, interferon-gamma [IFN-γ]).

Risk Classification Examples

Inpatient Settings with More Than 200 Beds

If less than six TB patients for the preceding year, classify as low risk. If greater than or equal to six TB patients for the preceding year, classify as medium risk.

Inpatient Settings with Less Than 200 Beds

If less than three TB patients for the preceding year, classify as low risk. If greater than or equal to three TB patients for the preceding year, classify as medium risk.

Outpatient, Outreach, and Home-Based Health-Care Settings

If less than three TB patients for the preceding year, classify as low risk. If greater than or equal to three TB patients for the preceding year, classify as medium risk.

Hypothetical Risk Classification Examples

The following hypothetical situations illustrate how assessment data are used to assign a risk classification. The risk classifications are for settings in which patients with suspected or confirmed infectious TB disease are expected to be encountered.

Example A. The setting is a 150-bed hospital located in a small city. During the preceding year, the hospital admitted two patients with a diagnosis of TB disease. One was admitted directly to an AII room, and one stayed on a medical ward for 2 days before being placed in an AII room. A contact investigation of exposed HCWs by hospital infection-control personnel in consultation with the state or local health department did not identify any health-care–associated transmission. Risk classification: low risk.

Example B. The setting is an ambulatory-care site in which a TB clinic is held 2 days per week. During the preceding year, care was delivered to six patients with TB disease and approximately 50 persons with LTBI. No instances of transmission of M. tuberculosis were noted. Risk classification: medium risk (because it is a TB clinic).

Example C. The setting is a large publicly funded hospital in a major metropolitan area. The hospital admits an average of 150 patients with TB disease each year, comprising 35% of the city burden. The setting has a strong TB infection-control program (i.e., annually updates infection-control plan, fully implements infection-control plan, and has enough AII rooms [see Environmental Controls]) and an annual conversion rate (for tests for M. tuberculosis infection) among HCWs of 0.5%. No evidence of health-care–associated transmission is apparent. The hospital has strong collaborative linkages with the state or local health department. Risk classification: medium risk (with close ongoing surveillance for episodes of transmission from unrecognized cases of TB disease, test conversions for M. tuberculosis infection in HCWs as a result of health-care–associated transmission, and specific groups or areas in which a higher risk for health-care–associated transmission exists).

Example D. The setting is an inpatient area of a correctional facility. A proportion of the inmates were born in countries where TB disease is endemic. Two cases of TB disease were diagnosed in inmates during the preceding year. Risk classification: medium risk (Correctional facilities should be classified as at least medium risk).

Example E. A hospital located in a large city admits 35 patients with TB disease per year, uses QFT-G to measure M. tuberculosis infection, and has an overall HCW M. tuberculosis infection test conversion rate of 1.0%. However, on annual testing, three of the 20 respiratory therapists tested had QFT-G conversions, for a rate of 15%. All of the respiratory therapists who tested positive received medical evaluations, had TB disease excluded, were diagnosed with LTBI, and were offered and completed a course of treatment for LTBI. None of the respiratory therapists had known exposures to M. tuberculosis outside the hospital. The problem evaluation revealed that 1) the respiratory therapists who converted had spent part of their time in the pulmonary function laboratory where induced sputum specimens were collected, and 2) the ventilation in the laboratory was inadequate. Risk classification: potential ongoing transmission for the respiratory therapists (because of evidence of health-care–associated transmission). The rest of the setting was classified as medium risk. To address the problem, booths were installed for sputum induction. On subsequent testing for M. tuberculosis infection, no conversions were noted at the repeat testing 3 months later, and the respiratory therapists were then reclassified back to medium risk.

Example F. The setting is an ambulatory-care center associated with a large health maintenance organization (HMO). The patient volume is high, and the HMO is located in the inner city where TB rates are the highest in the state. During the preceding year, one patient who was known to have TB disease was evaluated at the center. The person was recognized as a TB patient on his first visit and was promptly triaged to an ED with an AII room capacity. While in the ambulatory-care center, the patient was held in an area separate from HCWs and other patients and instructed to wear a surgical or procedure mask, if possible. QFT-G was used for infection-control surveillance purposes, and a contact investigation was conducted among exposed staff, and no QFT-G conversions were noted. Risk classification: low risk.

Example G. The setting is a clinic for the care of persons infected with HIV. The clinic serves a large metropolitan area and a patient population of 2,000. The clinic has an AII room and a TB infection-control program. All patients are screened for TB disease upon enrollment, and airborne precautions are promptly initiated for anyone with respiratory complaints while the patient is being evaluated. During the preceding year, seven patients who were encountered in the clinic were subsequently determined to have TB disease. All patients were promptly put into an AII room, and no contact investigations were performed. The local health department was promptly notified in all cases. Annual TST has determined a conversion rate of 0.3%, which is low compared with the rate of the hospital with which the clinic is associated. Risk classification: medium risk (because persons infected with HIV might be encountered).

Example H. A home health-care agency employs 125 workers, many of whom perform duties, including nursing, physical therapy, and basic home care. The agency did not care for any patients with suspected or confirmed TB disease during the preceding year. Approximately 30% of the agency's workers are foreign-born, many of whom have immigrated within the previous 5 years. At baseline two-step testing, four had a positive initial TST result, and two had a positive second-step TST result. All except one of these workers was foreign-born. Upon further screening, none were determined to have TB disease. The home health-care agency is based in a major metropolitan area and delivers care to a community where the majority of persons are poor and medically underserved and TB case rates are higher than the community as a whole. Risk classification: low risk (because HCWs might be from populations at higher risk for LTBI and subsequent progression to TB disease because of foreign birth and recent immigration or HIV-infected clients might be overrepresented, medium risk could be considered).

Screening HCWs Who Transfer to Other Health-Care Settings

All HCWs should receive baseline TB screening, even in settings considered to be low risk. Infection-control plans should address HCWs who transfer from one health-care setting to another and consider that the transferring HCWs might be at an equivalent or higher risk for exposure in different settings. Infection-control plans might need to be customized to balance the assessed risks and the efficacy of the plan based on consideration of various logistical factors. Guidance is provided based on different scenarios.

Because some institutions might adopt BAMT for the purposes of testing for M. tuberculosis infection, infection-control programs might be confronted with interpreting historic and current TST and BAMT results when HCWs transfer to a different setting. On a case-by-case basis, expert medical opinion might be needed to interpret results and refer patients with discordant BAMT and TST baseline results. Therefore, infection-control programs should keep all records when documenting previous test results. For example, an infection-control program using a BAMT strategy should request and keep historic TST results of a HCW transferring from a previous setting. Even if the HCW is transferring from a setting that used BAMT to a setting that uses BAMT, historic TST results might be needed when in the future the HCW transfers to a setting that uses TST. Similarly, historic BAMT results might be needed when the HCW transfers from a setting that used TST to a setting that uses BAMT.

HCWs transferring from low-risk to low-risk settings. After a baseline result for infection with M. tuberculosis is established and documented, serial testing for M. tuberculosis infection is not necessary.

HCWs transferring from low-risk to medium-risk settings. After a baseline result for infection with M. tuberculosis is established and documented, annual TB screening (including a symptom screen and TST or BAMT for persons with previously negative test results) should be performed.

HCWs transferring from low- or medium-risk settings to settings with a temporary classification of potential ongoing transmission. After a baseline result for infection with M. tuberculosis is established, a decision should be made regarding follow-up screening on an individual basis. If transmission seems to be ongoing, consider including the HCW in the screenings every 8–10 weeks until a determination has been made that ongoing transmission has ceased. When the setting is reclassified back to medium-risk, annual TB screening should be resumed.

Calculation and Use of Conversion Rates for M. tuberculosis Infection

The M. tuberculosis infection conversion rate is the percentage of HCWs whose test result for M. tuberculosis infection has converted within a specified period. Timely detection of M. tuberculosis infection in HCWs not only facilitates treatment for LTBI, but also can indicate the need for a source case investigation and a revision of the risk assessment for the setting. Conversion in test results for M. tuberculosis, regardless of the testing method used, is usually interpreted as presumptive evidence of new M. tuberculosis infection, and recent infections are associated with an increased risk for progression to TB disease.

For administrative purposes, a TST conversion is ≥10 mm increase in the size of the TST induration during a 2-year period in 1) an HCW with a documented negative (<10 mm) baseline two-step TST result or 2) a person who is not an HCW with a negative (<10 mm) TST result within 2 years.

In settings conducting serial testing for M. tuberculosis infection (medium-risk settings), use the following steps to estimate the risk for test conversion in HCWs.

  • Calculate a conversion rate by dividing the number of conversions among HCWs in the setting in a specified period (numerator) by the number of HCWs who received tests in the setting over the same period (denominator) multiplied by 100 (see Use of Conversion Test Data for M. tuberculosis Infection To Identify Lapses in Infection Control).
  • Identify areas or groups in the setting with a potentially high risk for M. tuberculosis transmission by comparing conversion rates in HCWs with potential exposure to patients with TB disease to conversion rates in HCWs for whom health-care–associated exposure to M. tuberculosis is not probable.

Use of Conversion Test Data for M. tuberculosis Infection To Identify Lapses in Infection Control

  • Conversion rates above the baseline level (which will be different in each setting) should instigate an investigation to evaluate the likelihood of health-care–associated transmission. When testing for M. tuberculosis infection, if conversions are determined to be the result of well-documented community exposure or probable false-positive test results, then the risk classification of the setting does not need to be adjusted.
  • For settings that no longer perform serial testing for M. tuberculosis infection among HCWs, reassessment of the risk for the setting is essential to ensure that the infection-control program is effective. The setting should have ongoing communication with the local or state health department regarding incidence and epidemiology of TB in the population served and should ensure that timely contact investigations are performed for HCWs or patients with unprotected exposure to a person with TB disease.

Example Calculation of Conversion Rates

Medical Center A is classified as medium risk and uses TST for annual screening. At the end of 2004, a total of 10,051 persons were designated as HCWs. Of these, 9,246 had negative baseline test results for M. tuberculosis infection. Of the HCWs tested, 10 experienced an increase in TST result by ≥10 mm. The overall setting conversion rate for 2004 is 0.11%. If five of the 10 HCWs whose test results converted were among the 100 HCWs employed in the ICU of Hospital X (in Medical Center A), then the ICU setting-specific conversion rate for 2004 is 5%.

Evaluation of HCWs for LTBI should include information from a serial testing program, but this information must be interpreted as only one part of a full assessment. TST or BAMT conversion criteria for administrative (surveillance) purposes are not applicable for medical evaluation of HCWs for the diagnosis of LTBI (see Supplement, Surveillance and Detection of M. tuberculosis Infections in Health-Care Workers [HCWs]).

Evaluation of TB Infection-Control Procedures and Identification of Problems

Annual evaluations of the TB infection-control plan are needed to ensure the proper implementation of the plan and to recognize and correct lapses in infection control. Previous hospital admissions and outpatient visits of patients with TB disease should be noted before the onset of TB symptoms. Medical records of a sample of patients with suspected and confirmed TB disease who were treated or examined at the setting should be reviewed to identify possible problems in TB infection control. The review should be based on the factors listed on the TB Risk Assessment Worksheet (Appendix B).

  • Time interval from suspicion of TB until initiation of airborne precautions and antituberculosis treatment to:
    — suspicion of TB disease and patient triage to proper AII room or referral center for settings that do not provide care for patients with suspected or confirmed TB disease;
    — admission until TB disease was suspected;
    — admission until medical evaluation for TB disease was performed;
    — admission until specimens for AFB smears and polymerase chain reaction (PCR)–based nucleic acid amplification (NAA) tests for M. tuberculosis were ordered;
    — admission until specimens for mycobacterial culture were ordered;
    — ordering of AFB smears, NAA tests, and mycobacterial culture until specimens were collected;
    — collection of specimens until performance and AFB smear results were reported;
    — collection of specimens until performance and culture results were reported;
    — collection of specimens until species identification was reported;
    — collection of specimens until drug-susceptibility test results were reported;
    — admission until airborne precautions were initiated; and
    — admission until antituberculosis treatment was initiated.
  • Duration of airborne precautions.
  • Measurement of meeting criteria for discontinuing airborne precautions. Certain patients might be correctly discharged from an AII room to home.
  • Patient history of previous admission.
  • Adequacy of antituberculosis treatment regimens.
  • Adequacy of procedures for collection of follow-up sputum specimens.
  • Adequacy of discharge planning.
  • Number of visits to outpatient setting from the start of symptoms until TB disease was suspected (for outpatient settings).

Work practices related to airborne precautions should be observed to determine if employers are enforcing all practices, if HCWs are adhering to infection-control policies, and if patient adherence to airborne precautions is being enforced. Data from the case reviews and observations in the annual risk assessment should be used to determine the need to modify 1) protocols for identifying and initiating prompt airborne precautions for patients with suspected or confirmed infectious TB disease, 2) protocols for patient management, 3) laboratory procedures, or 4) TB training and education programs for HCWs.

Environmental Assessment

  • Data from the most recent environmental evaluation should be reviewed to determine if recommended environmental controls are in place (see Suggested Components of an Initial TB Training and Education Program for HCWs).
  • Environmental control maintenance procedures and logs should be reviewed to determine if maintenance is conducted properly and regularly.
  • Environmental control design specifications should be compared with guidelines from the American Institute of Architects (AIA) and other ventilation guidelines (117,118) (see Risk Classification Examples) and the installed system performance.
  • Environmental data should be used to assist building managers and engineers in evaluating the performance of the installed system.
  • The number and types of aerosol-generating or aerosol-producing procedures (e.g., specimen processing and manipulation, bronchoscopy, sputum induction, and administration of aerosolized medications) performed in the setting should be assessed.
  • The number of AII rooms should be suitable for the setting based on AIA Guidelines and the setting risk assessment. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has adapted the AIA guidelines when accrediting facilities (118).

Suggested Components of an Initial TB Training and Education Program for HCWs

The following are suggested components of an initial TB training and education program:

1. Clinical Information

Basic concepts of M. tuberculosis transmission, pathogenesis, and diagnosis, including the difference between LTBI and TB disease and the possibility of reinfection after previous infection with M. tuberculosis or TB disease.

  • Symptoms and signs of TB disease and the importance of a high index of suspicion for patients or HCWs with these symptoms.
  • Indications for initiation of airborne precautions of inpatients with suspected or confirmed TB disease.
  • Policies and indications for discontinuing airborne precautions.
  • Principles of treatment for LTBI and for TB disease (indications, use, effectiveness, and potential adverse effects).

2. Epidemiology of TB

  • Epidemiology of TB in the local community, the United States, and worldwide.
  • Risk factors for TB disease.

3. Infection-Control Practices to Prevent and Detect M. tuberculosis Transmission in Health-Care Settings

  • Overview of the TB infection-control program.
  • Potential for occupational exposure to infectious TB disease in health-care settings.
  • Principles and practices of infection control to reduce the risk for transmission of M. tuberculosis, including the hierarchy of TB infection-control measures, written policies and procedures, monitoring, and control measures for HCWs at increased risk for exposure to M. tuberculosis.
  • Rationale for infection-control measures and documentation evaluating the effect of these measures in reducing occupational TB risk exposure and M. tuberculosis transmission.
  • Reasons for testing for M. tuberculosis infection, importance of a positive test result for M. tuberculosis infection, importance of participation in a TB screening program, and importance of retaining documentation of previous test result for M. tuberculosis infection, chest radiograph results, and treatment for LTBI and TB disease.
  • Efficacy and safety of BCG vaccination and principles of screening for M. tuberculosis infection and interpretation in BCG recipients.
  • Procedures for investigating an M. tuberculosis infection test conversion or TB disease occurring in the workplace.
  • Joint responsibility of HCWs and employers to ensure prompt medical evaluation after M. tuberculosis test conversion or development of symptoms or signs of TB disease in HCWs.
  • Role of HCW in preventing transmission of M. tuberculosis.
  • Responsibility of HCWs to promptly report a diagnosis of TB disease to the setting's administration and infection-control program.
  • Responsibility of clinicians and the infection-control program to report to the state or local health department a suspected case of TB disease in a patient (including autopsy findings) or HCW.
  • Responsibilities and policies of the setting, the local health department, and the state health department to ensure confidentiality for HCWs with TB disease or LTBI.
  • Responsibility of the setting to inform EMS staff who transported a patient with suspected or confirmed TB disease.
  • Responsibilities and policies of the setting to ensure that an HCW with TB disease is noninfectious before returning to duty.
  • Importance of completing therapy for LTBI or TB disease to protect the HCW's health and to reduce the risk to others.
  • Proper implementation and monitoring of environmental controls (see Environmental Controls).
  • Training for safe collection, management, and disposal of clinical specimens.
  • Required Occupational Safety and Health Administration (OSHA) record keeping on HCW test conversions for M. tuberculosis infection.
  • Record-keeping and surveillance of TB cases among patients in the setting.
  • Proper use of (see Respiratory Protection) and the need to inform the infection-control program of factors that might affect the efficacy of respiratory protection as required by OSHA.
  • Success of adherence to infection-control practices in decreasing the risk for transmission of M. tuberculosis in health-care settings.

4. TB and Immunocompromising Conditions

  • Relationship between infection with M. tuberculosis and medical conditions and treatments that can lead to impaired immunity.
  • Available tests and counseling and referrals for persons with HIV infection, diabetes, and other immunocompromising conditions associated with an increased risk for progression to TB disease.
  • Procedures for informing employee health or infection-control personnel of medical conditions associated with immunosuppression.
  • Policies on voluntary work reassignment options for immunocompromised HCWs.
  • Applicable confidentiality safeguards of the health-care setting, locality, and state.

5. TB and Public Health

  • Role of the local and state health department's TB-control program in screening for LTBI and TB disease, providing treatment, conducting contact investigations and outbreak investigations, and providing education, counseling, and responses to public inquiries.
  • Roles of CDC and of OSHA.
  • Availability of information, advice, and counseling from community sources, including universities, local experts, and hotlines.
  • Responsibility of the setting's clinicians and infection-control program to promptly report to the state or local health department a case of suspected TB disease or a cluster of TST or BAMT conversions.
  • Responsibility of the setting's clinicians and infection-control program to promptly report to the state or local health department a person with suspected or confirmed TB disease who leaves the setting against medical advice.

Managing Patients Who Have Suspected or Confirmed TB Disease: General Recommendations

The primary TB risk to HCWs is the undiagnosed or unsuspected patient with infectious TB disease. A high index of suspicion for TB disease and rapid implementation of precautions are essential to prevent and interrupt transmission. Specific precautions will vary depending on the setting.

Prompt Triage

Within health-care settings, protocols should be implemented and enforced to promptly identify, separate from others, and either transfer or manage persons who have suspected or confirmed infectious TB disease. When patients' medical histories are taken, all patients should be routinely asked about 1) a history of TB exposure, infection, or disease; 2) symptoms or signs of TB disease; and 3) medical conditions that increase their risk for TB disease (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease). The medical evaluation should include an interview conducted in the patient's primary language, with the assistance of a qualified medical interpreter, if necessary. HCWs who are the first point of contact should be trained to ask questions that will facilitate detection of persons who have suspected or confirmed infectious TB disease. For assistance with language interpretation, contact the local and state health department. Interpretation resources are also available (119) at http://www.atanet.org; http://www.languageline.com; and http://www.ncihc.org.

A diagnosis of respiratory TB disease should be considered for any patient with symptoms or signs of infection in the lung, pleura, or airways (including larynx), including coughing for ≥3 weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum or hemoptysis, hoarseness, fever, fatigue, or chest pain. The index of suspicion for TB disease will vary by geographic area and will depend on the population served by the setting. The index of suspicion should be substantially high for geographic areas and groups of patients characterized by high TB incidence (26).

Special steps should be taken in settings other than TB clinics. Patients with symptoms suggestive of undiagnosed or inadequately treated TB disease should be promptly referred so that they can receive a medical evaluation. These patients should not be kept in the setting any longer than required to arrange a referral or transfer to an AII room. While in the setting, symptomatic patients should wear a surgical or procedure mask, if possible, and should be instructed to observe strict respiratory hygiene and cough etiquette procedures (see Glossary) (120–122).

Immunocompromised persons, including those who are HIV-infected, with infectious TB disease should be physically separated from other persons to protect both themselves and others. To avoid exposing HIV-infected or otherwise severely immunocompromised persons to M. tuberculosis, consider location and scheduling issues to avoid exposure.

TB Airborne Precautions

Within health-care settings, TB airborne precautions should be initiated for any patient who has symptoms or signs of TB disease, or who has documented infectious TB disease and has not completed antituberculosis treatment. For patients placed in AII rooms because of suspected infectious TB disease of the lungs, airway, or larynx, airborne precautions may be discontinued when infectious TB disease is considered unlikely and either 1) another diagnosis is made that explains the clinical syndrome or 2) the patient has three consecutive, negative AFB sputum smear results (109–112,123). Each of the three sputum specimens should be collected in 8–24-hour intervals (124), and at least one specimen should be an early morning specimen because respiratory secretions pool overnight. Generally, this method will allow patients with negative sputum smear results to be released from airborne precautions in 2 days.

The classification of the risk assessment of the health-care setting is used to determine how many AII rooms each setting needs, depending on the number of TB patients examined. At least one AII room is needed for settings in which TB patients stay while they are being treated, and additional AII rooms might be needed depending on the magnitude of patient-days of persons with suspected or confirmed TB disease (118). Additional rooms might be considered if options are limited for transferring patients with suspected or confirmed TB disease to other settings with AII rooms. For example, for a hospital with 120 beds, a minimum of one AII room is needed, possibly more, depending on how many TB patients are examined in 1 year.

TB Airborne Precautions for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

Settings that plan to evaluate and manage patients with TB disease should have at least one AII room or enclosure that meets AII requirements (see Environmental Controls; and Supplement, Environmental Controls). These settings should develop written policies that specify 1) indications for airborne precautions, 2) persons authorized to initiate and discontinue airborne precautions, 3) specific airborne precautions, 4) AII room-monitoring procedures, 5) procedures for managing patients who do not adhere to airborne precautions, and 6) criteria for discontinuing airborne precautions.

A high index of suspicion should be maintained for TB disease. If a patient has suspected or confirmed TB disease, airborne precautions should be promptly initiated. Persons with suspected or confirmed TB disease who are inpatients should remain in AII rooms until they are determined to be noninfectious and have demonstrated a clinical response to a standard multidrug antituberculosis treatment regimen or until an alternative diagnosis is made. If the alternative diagnosis cannot be clearly established, even with three negative sputum smear results, empiric treatment of TB disease should strongly be considered (see Supplement, Estimating the Infectiousness of a TB Patient). Outpatients with suspected or confirmed infectious TB disease should remain in AII rooms until they are transferred or until their visit is complete.

TB Airborne Precautions for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

Settings in which patients with suspected or confirmed TB disease are not expected to be encountered do not need an AII room or a respiratory-protection program for the prevention of transmission of M. tuberculosis. However, follow these steps in these settings.

A written protocol should be developed for referring patients with suspected or confirmed TB disease to a collaborating referral setting in which the patient can be evaluated and managed properly. The referral setting should provide documentation of intent to collaborate. The protocol should be reviewed routinely and revised as needed.

Patients with suspected or confirmed TB disease should be placed in an AII room, if available, or in a room that meets the requirements for an AII room, or in a separate room with the door closed, apart from other patients and not in an open waiting area. Adequate time should elapse to ensure removal of M. tuberculosis–contaminated room air before allowing entry by staff or another patient (Tables 1 and 2).

If an AII room is not available, persons with suspected or confirmed infectious TB disease should wear a surgical or procedure mask, if possible. Patients should be instructed to keep the mask on and to change the mask if it becomes wet. If patients cannot tolerate a mask, they should observe strict respiratory hygiene and cough etiquette procedures.

AII Room Practices

AII rooms should be single-patient rooms in which environmental factors and entry of visitors and HCWs are controlled to minimize the transmission of M. tuberculosis. All HCWs who enter an AII room should wear at least N95 disposable respirators (see Respiratory Protection). Visitors may be offered respiratory protection (i.e., N95) and should be instructed by HCWs on the use of the respirator before entering an AII room. AII rooms have specific requirements for controlled ventilation, negative pressure, and air filtration (118) (see Environmental Controls). Each inpatient AII room should have a private bathroom.

Settings with AII Rooms

Health-care personnel settings with AII rooms should

  • keep doors to AII rooms closed except when patients, HCWs, or others must enter or exit the room (118);
  • maintain enough AII rooms to provide airborne precautions of all patients who have suspected or confirmed TB disease. Estimate the number of AII rooms needed based on the results of the risk assessment for the setting;
  • monitor and record direction of airflow (i.e., negative pressure) in the room on a daily basis, while the room is being used for TB airborne precautions. Record results in an electronic or readily retrievable document;
  • consider grouping AII rooms in one part of the health-care setting to limit costs, reduce the possibility of transmitting M. tuberculosis to other patients, facilitate the care of TB patients, and facilitate the installation and maintenance of optimal environmental controls (particularly ventilation). Depending on the architecture and the environmental control systems of a particular setting, AII rooms might be grouped either horizontally (e.g., a wing of a facility) or vertically (e.g., the last few rooms of separate floors of a facility);
  • perform diagnostic and treatment procedures (e.g., sputum collection and inhalation therapy) in an AII room.
  • ensure patient adherence to airborne precautions. In their primary language, with the assistance of a qualified medical interpreter, if necessary, educate patients (and family and visitors) who are placed in an AII room about M. tuberculosis transmission and the reasons for airborne precautions. For assistance with language interpretation, contact the local and state health department. Interpretation resources are available (119) at http://www.atanet.org; http://www.languageline.com; and http://www.ncihc.org. Facilitate patient adherence by using incentives (e.g., provide telephones, televisions, or radios in AII rooms; and grant special dietary requests) and other measures. Address problems that could interfere with adherence (e.g., management of withdrawal from addictive substances, including tobacco); and
  • ensure that patients with suspected or confirmed infectious TB disease who must be transported to another area of the setting or to another setting for a medically essential procedure bypass the waiting area and wear a surgical or procedure mask, if possible. Drivers, HCWs, and other staff who are transporting persons with suspected or confirmed infectious TB disease might consider wearing an N95 respirator. Schedule procedures on patients with TB disease when a minimum number of HCWs and other patients are present and as the last procedure of the day to maximize the time available for removal of airborne contamination (Tables 1 and 2).

Diagnostic Procedures

Diagnostic procedures should be performed in settings with appropriate infection-control capabilities. The following recommendations should be applied for diagnosing TB disease and for evaluating patients for potential infectiousness.

Clinical Diagnosis

A complete medical history should be obtained, including symptoms of TB disease, previous TB disease and treatment, previous history of infection with M. tuberculosis, and previous treatment of LTBI or exposure to persons with TB disease. A physical examination should be performed, including chest radiograph, microscopic examination, culture, and, when indicated, NAA testing of sputum (39,53,125,126). If possible, sputum induction with aerosol inhalation is preferred, particularly when the patient cannot produce sputum. Gastric aspiration might be necessary for those patients, particularly children, who cannot produce sputum, even with aerosol inhalation (127–130). Bronchoscopy might be needed for specimen collection, especially if sputum specimens have been nondiagnostic and doubt exists as to the diagnosis (90,111,127,128,131–134).

All patients with suspected or confirmed infectious TB disease should be placed under airborne precautions until they have been determined to be noninfectious (see Supplement, Estimating the Infectiousness of a TB Patient). Adult and adolescent patients who might be infectious include persons who are coughing; have cavitation on chest radiograph; have positive AFB sputum smear results; have respiratory tract disease with involvement of the lung, pleura or airways, including larynx, who fail to cover the mouth and nose when coughing; are not on antituberculosis treatment or are on incorrect antituberculosis treatment; or are undergoing cough-inducing or aerosol-generating procedures (e.g., sputum induction, bronchoscopy, and airway suction) (30,135).

Persons diagnosed with extrapulmonary TB disease should be evaluated for the presence of concurrent pulmonary TB disease. An additional concern in infection control with children relates to adult household members and visitors who might be the source case (136). Pediatric patients, including adolescents, who might be infectious include those who have extensive pulmonary or laryngeal involvement, prolonged cough, positive sputum AFB smears results, cavitary TB on chest radiograph (as is typically observed in immunocompetent adults with TB disease), or those for whom cough-inducing or aerosol-generating procedures are performed (136,137).

Although children are uncommonly infectious, pediatric patients should be evaluated for infectiousness by using the same criteria as for adults (i.e., on the basis of pulmonary or laryngeal involvement). Patients with suspected or confirmed TB disease should be immediately reported to the local public health authorities so that arrangements can be made for tracking their treatment to completion, preferably through a case management system, so that DOT can be arranged and standard procedures for identifying and evaluating TB contacts can be initiated. Coordinate efforts with the local or state health department to arrange treatment and long-term follow-up and evaluation of contacts.

Laboratory Diagnosis

To produce the highest quality laboratory results, laboratories performing mycobacteriologic tests should be skilled in both the laboratory and the administrative aspects of specimen processing. Laboratories should use or have prompt access to the most rapid methods available: 1) fluorescent microscopy and concentration for AFB smears; 2) rapid NAA testing for direct detection of M. tuberculosis in patient specimens (125); 3) solid and rapid broth culture methods for isolation of mycobacteria; 4) nucleic acid probes or high pressure liquid chromatography (HPLC) for species identification; and 5) rapid broth culture methods for drug susceptibility testing. Laboratories should incorporate other more rapid or sensitive tests as they become available, practical, and affordable (see Supplement, Diagnostic Procedures for LTBI and TB Disease) (138,139).

In accordance with local and state laws and regulations, a system should be in place to ensure that laboratories report any positive results from any specimens to clinicians within 24 hours of receipt of the specimen (139,140). Certain settings perform AFB smears on-site for rapid results (and results should be reported to clinicians within 24 hours) and then send specimens or cultures to a referral laboratory for identification and drug-susceptibility testing. This referral practice can speed the receipt of smear results but delay culture identification and drug-susceptibility results. Settings that cannot provide the full range of mycobacteriologic testing services should contract with their referral laboratories to ensure rapid results while maintaining proficiency for on-site testing. In addition, referral laboratories should be instructed to store isolates in case additional testing is necessary.

All drug susceptibility results on M. tuberculosis isolates should be reported to the local or state health department as soon as these results are available. Laboratories that rarely receive specimens for mycobacteriologic analysis should refer specimens to a laboratory that performs these tests routinely. The reference laboratory should provide rapid testing and reporting. Out-of-state reference laboratories should provide all results to the local or state health department from which the specimen originated.

Special Considerations for Persons Who Are at High Risk for TB Disease or in Whom TB Disease Might Be Difficult to Diagnose

The probability of TB disease is higher among patients who 1) previously had TB disease or were exposed to M. tuberculosis, 2) belong to a group at high risk for TB disease or, 3) have a positive TST or BAMT result. TB disease is strongly suggested if the diagnostic evaluation reveals symptoms or signs of TB disease, a chest radiograph consistent with TB disease, or AFB in sputum or from any other specimen. TB disease can occur simultaneously in immunocompromised persons who have pulmonary infections caused by other organisms (e.g., Pneumocystis jaroveci [formerly P. carinii] and M. avium complex) and should be considered in the diagnostic evaluation of all such patients with symptoms or signs of TB disease (53).

TB disease can be difficult to diagnose in persons who have HIV infection (49) (or other conditions associated with severe suppression of cell mediated immunity) because of nonclassical or normal radiographic presentation or the simultaneous occurrence of other pulmonary infections (e.g., P. jaroveci or M. avium complex) (2). Patients who are HIV-infected are also at greater risk for having extrapulmonary TB (2). The difficulty in diagnosing TB disease in HIV-infected can be compounded by the possible lower sensitivity and specificity of sputum smear results for detecting AFB (53,141) and the overgrowth of cultures with M. avium complex in specimens from patients infected with both M. tuberculosis and M. avium complex. The TST in patients with advanced HIV infection is unreliable and cannot be used in clinical decision making (35,53,142).

For immunocompromised patients who have respiratory symptoms or signs that are attributed initially to infections or conditions other than TB disease, conduct an evaluation for coexisting TB disease. If the patient does not respond to recommended treatment for the presumed cause of the pulmonary abnormalities, repeat the evaluation (see Supplement, Diagnostic Procedures for LTBI and TB Disease). In certain settings in which immunocompromised patients and patients with TB disease are examined, implementing airborne precautions might be prudent for all persons at high risk. These persons include those infected with HIV who have an abnormal chest radiograph or respiratory symptoms, symptomatic foreign-born persons who have immigrated within the previous 5 years from TB-endemic countries, and persons with pulmonary infiltrates on chest radiograph, or symptoms or signs of TB disease.

Initiation of Treatment

For patients who have confirmed TB disease or who are considered highly probable to have TB disease, promptly start antituberculosis treatment in accordance with current guidelines (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease) (31). In accordance with local and state regulations, local health departments should be notified of all cases of suspected TB.

DOT is the standard of care for all patients with TB disease and should be used for all doses during the course of therapy for treatment of TB disease. All inpatient medication should be administered by DOT and reported to the state or local health department. Rates of relapse and development of drug-resistance are decreased when DOT is used (143–145). All patients on intermittent (i.e., once or twice per week) treatment for TB disease or LTBI should receive DOT. Settings should collaborate with the local or state health department on decisions concerning inpatient DOT and arrangements for outpatient DOT (31).

Managing Patients Who Have Suspected or Confirmed TB Disease: Considerations for Special Circumstances and Settings

The recommendations for preventing transmission of M. tuberculosis are applicable to all health-care settings, including those that have been described (Appendix A). These settings should each have independent risk assessments if they are stand-alone settings, or each setting should have a detailed section written as part of the risk assessment for the overall setting.

Minimum Requirements

The specific precautions for the settings included in this section vary, depending on the setting.

Inpatient Settings

Emergency Departments (EDs)

The symptoms of TB disease are usually symptoms for which patients might seek treatment in EDs. Because TB symptoms are common and nonspecific, infectious TB disease could be encountered in these settings. The use of ED-based TB screening has not been demonstrated to be consistently effective (146).

The amount of time patients with suspected or confirmed infectious TB disease spend in EDs and urgent-care settings should be minimized. Patients with suspected or confirmed infectious TB disease should be promptly identified, evaluated, and separated from other patients. Ideally, such patients should be placed in an AII room. When an AII room is not available, use a room with effective general ventilation, and use air cleaning technologies (e.g., a portable HEPA filtration system), if available, or transfer the patient to a setting or area with recommended infection-control capacity. Facility engineering personnel with expertise in heating, ventilation, and air conditioning (HVAC) and air handlers have evaluated how this option is applied to ensure no over pressurization of return air or unwanted deviations exists in design of air flow in the zone.

EDs with a high volume of patients with suspected or confirmed TB disease should have at least one AII room (see TB Risk Assessment). Air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase equivalent air changes per hour (ACH) in waiting areas (Table 1). HCWs entering an AII room or any room with a patient with infectious TB disease should wear at least an N95 disposable respirator. After a patient with suspected or confirmed TB disease exits a room, allow adequate time to elapse to ensure removal of M. tuberculosis-contaminated room air before allowing entry by staff or another patient (Tables 1 and 2).

Before a patient leaves an AII room, perform an assessment of 1) the patient's need to discontinue airborne precautions, 2) the risk for transmission and the patient's ability to observe strict respiratory hygiene, and 3) cough etiquette procedures. Patients with suspected or confirmed infectious TB who are outside an AII room should wear a surgical or procedure mask, if possible. Patients who cannot tolerate masks because of medical conditions should observe strict respiratory hygiene and cough etiquette procedures.

Intensive Care Units (ICUs)

Patients with infectious TB disease might become sick enough to require admission to an ICU. Place ICU patients with suspected or confirmed infectious TB disease in an AII room, if possible. ICUs with a high volume of patients with suspected or confirmed TB disease should have at least one AII room (Appendix B). Air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase equivalent ACH in waiting areas (see Environmental Controls).

HCWs entering an AII room or any room with a patient with infectious TB disease should wear at least an N95 disposable respirator. To help reduce the risk for contaminating a ventilator or discharging M. tuberculosis into the ambient air when mechanically ventilating (i.e., with a ventilator or manual resuscitator) a patient with suspected or confirmed TB disease, place a bacterial filter on the patient's endotracheal tube (or at the expiratory side of the breathing circuit of a ventilator) (147–151). In selecting a bacterial filter, give preference to models specified by the manufacturer to filter particles 0.3 µm in size in both the unloaded and loaded states with a filter efficiency of ≥95% (i.e., filter penetration of <5%) at the maximum design flow rates of the ventilator for the service life of the filter, as specified by the manufacturer.

Surgical Suites

Surgical suites require special infection-control considerations for preventing transmission of M. tuberculosis. Normally, the direction of airflow should be from the operating room (OR) to the hallway (positive pressure) to minimize contamination of the surgical field. Certain hospitals have procedure rooms with reversible airflow or pressure, whereas others have positive-pressure rooms with a negative pressure anteroom. Surgical staff, particularly those close to the surgical field, should use respiratory protection (e.g., a valveless N95 disposable respirator) to protect themselves and the patient undergoing surgery.

When possible, postpone non-urgent surgical procedures on patients with suspected or confirmed TB disease until the patient is determined to be noninfectious or determined to not have TB disease. When surgery cannot be postponed, procedures should be performed in a surgical suite with recommended ventilation controls. Procedures should be scheduled for patients with suspected or confirmed TB disease when a minimum number of HCWs and other patients are present in the surgical suite, and at the end of the day to maximize the time available for removal of airborne contamination (Tables 1 and 2).

If a surgical suite or an OR has an anteroom, the anteroom should be either 1) positive pressure compared with both the corridor and the suite or OR (with filtered supply air) or 2) negative pressure compared with both the corridor and the suite or OR. In the usual design in which an OR has no anteroom, keep the doors to the OR closed, and minimize traffic into and out of the room and in the corridor. Using additional air-cleaning technologies (e.g., UVGI) should be considered to increase the equivalent ACH. Air-cleaning systems can be placed in the room or in surrounding areas to minimize contamination of the surroundings after the procedure (114) (see Environmental Controls).

Ventilation in the OR should be designed to provide a sterile environment in the surgical field while preventing contaminated air from flowing to other areas in the health-care setting. Personnel steps should be taken to reduce the risk for contaminating ventilator or anesthesia equipment or discharging tubercle bacilli into the ambient air when operating on a patient with suspected or confirmed TB disease (152). A bacterial filter should be placed on the patient's endotracheal tube (or at the expiratory side of the breathing circuit of a ventilator or anesthesia machine, if used) (147–151). When selecting a bacterial filter, give preference to models specified by the manufacturer to filter particles 0.3 µm in size in both the unloaded and loaded states with a filter efficiency of ≥95% (i.e., filter penetration of <5%) at the maximum design flow rates of the ventilator for the service life of the filter, as specified by the manufacturer.

When surgical procedures (or other procedures that require a sterile field) are performed on patients with suspected or confirmed infectious TB, respiratory protection should be worn by HCWs to protect the sterile field from the respiratory secretions of HCWs and to protect HCWs from the infectious droplet nuclei generated from the patient. When selecting respiratory protection, do not use valved or positive-pressure respirators, because they do not protect the sterile field. A respirator with a valveless filtering facepiece (e.g., N95 disposable respirator) should be used.

Postoperative recovery of a patient with suspected or confirmed TB disease should be in an AII room in any location where the patient is recovering (118). If an AII or comparable room is not available for surgery or postoperative recovery, air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase the number of equivalent ACH (see Environmental Controls); however, the infection-control committee should be involved in the selection and placement of these supplemental controls.

Laboratories

Staff who work in laboratories that handle clinical specimens encounter risks not typically present in other areas of a health-care setting (153–155). Laboratories that handle TB specimens include 1) pass-through facilities that forward specimens to reference laboratories for analysis; 2) diagnostic laboratories that process specimens and perform acid-fast staining and primary culture for M. tuberculosis; and 3) facilities that perform extensive identification, subtyping, and susceptibility studies.

Procedures involving the manipulation of specimens or cultures containing M. tuberculosis introduce additional substantial risks that must be addressed in an effective TB infection-control program. Personnel who work with mycobacteriology specimens should be thoroughly trained in methods that minimize the production of aerosols and undergo periodic competency testing to include direct observation of their work practices. Risks for transmission of M. tuberculosis in laboratories include aerosol formation during any specimen or isolate manipulation and percutaneous inoculation from accidental exposures. Biosafety recommendations for laboratories performing diagnostic testing for TB have been published (74,75,138,156,157).

In laboratories affiliated with a health-care setting (e.g., a hospital) and in free-standing laboratories, the laboratory director, in collaboration with the infection-control staff for the setting, and in consultation with the state TB laboratory, should develop a risk-based infection-control plan for the laboratory that minimizes the risk for exposure to M. tuberculosis. Consider factors including 1) incidence of TB disease (including drug-resistant TB) in the community and in patients served by settings that submit specimens to the laboratory, 2) design of the laboratory, 3) level of TB diagnostic service offered, 4) number of specimens processed, and 5) whether or not aerosol-generating or aerosol-producing procedures are performed and the frequency at which they are performed. Referral laboratories should store isolates in case additional testing is necessary.

Biosafety level (BSL)-2 practices and procedures, containment equipment, and facilities are required for nonaerosol-producing manipulations of clinical specimens (e.g., preparing direct smears for acid-fast staining when done in conjunction with training and periodic checking of competency) (138). All specimens suspected of containing M. tuberculosis (including specimens processed for other microorganisms) should be handled in a Class I or II biological safety cabinet (BSC) (158,159). Conduct all aerosol-generating activities (e.g., inoculating culture media, setting up biochemical and antimicrobic susceptibility tests, opening centrifuge cups, and performing sonication) in a Class I or II BSC (158).

For laboratories that are considered at least medium risk (Appendix C), conduct testing for M. tuberculosis infection at least annually among laboratorians who perform TB diagnostics or manipulate specimens from which M. tuberculosis is commonly isolated (e.g., sputum, lower respiratory secretions, or tissues) (Appendix D). More frequent testing for M. tuberculosis is recommended in the event of a documented conversion among laboratory staff or a laboratory accident that poses a risk for exposure to M. tuberculosis (e.g., malfunction of a centrifuge leading to aerosolization of a sample).

Based on the risk assessment for the laboratory, employees should use personal protective equipment (including respiratory protection) recommended by local regulations for each activity. For activities that have a low risk for generating aerosols, standard personal protective equipment consists of protective laboratory coats, gowns, or smocks designed specifically for use in the laboratory. Protective garments should be left in the laboratory before going to nonlaboratory areas.

For all laboratory procedures, disposable gloves should be worn. Gloves should be disposed of when work is completed, the gloves are overtly contaminated, or the integrity of the glove is compromised. Local or state regulations should determine procedures for the disposal of gloves. Face protection (e.g., goggles, full-facepiece respirator, face shield, or other splatter guard) should also be used when manipulating specimens inside or outside a BSC. Use respiratory protection when performing procedures that can result in aerosolization outside a BSC. The minimum level of respiratory protection is an N95 filtering facepiece respirator. Laboratory workers who use respiratory protection should be provided with the same training on respirator use and care and the same fit testing as other HCWs.

After documented laboratory accidents, conduct an investigation of exposed laboratory workers. Laboratories in which specimens for mycobacteriologic studies (e.g., AFB smears and cultures) are processed should follow the AIA and CDC/National Institute of Health guidelines (118,159) (see Environmental Controls). BSL-3 practices, containment equipment, and facilities are recommended for the propagation and manipulation of cultures of M. tuberculosis complex (including M. bovis) and for animal studies in which primates that are experimentally or naturally infected with M. tuberculosis or M. bovis are used. Animal studies in which guinea pigs or mice are used can be conducted at animal BSL-2. Aerosol infection methods are recommended to be conducted at BSL-3 (159).

Bronchoscopy Suites

Because bronchoscopy is a cough-inducing procedure that might be performed on patients with suspected or confirmed TB disease, bronchoscopy suites require special attention (29,81,160,161). Bronchoscopy can result in the transmission of M. tuberculosis either through the airborne route (29,63,81,86,162) or a contaminated bronchoscope (80,82,163–170). Closed and effectively filtered ventilatory circuitry and minimizing opening of such circuitry in intubated and mechanically ventilated patients might minimize exposure (see Intensive Care Units) (149).

If possible, avoid bronchoscopy on patients with suspected or confirmed TB disease or postpone the procedure until the patient is determined to be noninfectious, by confirmation of the three negative AFB sputum smear results (109–112). When collection of spontaneous sputum specimen is not adequate or possible, sputum induction has been demonstrated to be equivalent to bronchoscopy for obtaining specimens for culture (110). Bronchoscopy might have the advantage of confirmation of the diagnosis with histologic specimens, collection of additional specimens, including post bronchoscopy sputum that might increase the diagnostic yield, and the opportunity to confirm an alternate diagnosis. If the diagnosis of TB disease is suspected, consideration should be given to empiric antituberculosis treatment.

A physical examination should be performed, and a chest radiograph, microscopic examination, culture, and NAA testing of sputum or other relevant specimens should also be obtained, including gastric aspirates (125), as indicated (53,126,131,130). Because 15%–20% of patients with TB disease have negative TST results, a negative TST result is of limited value in the evaluation of the patient with suspected TB disease, particularly in patients from high TB incidence groups in whom TST positive rates exceed 30% (31).

Whenever feasible, perform bronchoscopy in a room that meets the ventilation requirements for an AII room (same as the AIA guidelines parameters for bronchoscopy rooms) (see Environmental Controls). Air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase equivalent ACH.

If sputum specimens must be obtained and the patient cannot produce sputum, consider sputum induction before bronchoscopy (111). In a patient who is intubated and mechanically ventilated, minimize the opening of circuitry. At least N95 respirators should be worn by HCWs while present during a bronchoscopy procedure on a patient with suspected or confirmed infectious TB disease. Because of the increased risk for M. tuberculosis transmission during the performance of bronchoscopy procedures on patients with TB disease, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a powered air-purifying respirator [PAPR] [29]) (see Respiratory Protection).

After bronchoscopy is performed on a patient with suspected or confirmed infectious TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). During the period after bronchoscopy when the patient is still coughing, collect at least one sputum for AFB to increase the yield of the procedure. Patients with suspected or confirmed TB disease who are undergoing bronchoscopy should be kept in an AII room until coughing subsides.

Sputum Induction and Inhalation Therapy Rooms

Sputum induction and inhalation therapy induces coughing, which increases the potential for transmission of M. tuberculosis (87,88,90). Therefore, appropriate precautions should be taken when working with patients with suspected or confirmed TB disease. Sputum induction procedures for persons with suspected or confirmed TB disease should be considered after determination that self-produced sputum collection is inadequate and that the AFB smear result on other specimens collected is negative. HCWs who order or perform sputum induction or inhalation therapy in an environment without proper controls for the purpose of diagnosing conditions other than TB disease should assess the patient's risk for TB disease.

Cough-inducing or aerosol-generating procedures in patients with diagnosed TB should be conducted only after an assessment of infectiousness has been considered for each patient and should be conducted in an environment with proper controls. Sputum induction should be performed by using local exhaust ventilation (e.g., booths with special ventilation) or alternatively in a room that meets or exceeds the requirements of an AII room (see Environmental Controls) (90). At least an N95 disposable respirator should be worn by HCWs performing sputum inductions or inhalation therapy on a patient with suspected or confirmed infectious TB disease. Based on the risk assessment, consideration should be given to using a higher level of respiratory protection (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection) (90).

After sputum induction or inhalation therapy is performed on a patient with suspected or confirmed infectious TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). Patients with suspected or confirmed TB disease who are undergoing sputum induction or inhalation therapy should be kept in an AII room until coughing subsides.

Autopsy Suites

Autopsies performed on bodies with suspected or confirmed TB disease can pose a high risk for transmission of M. tuberculosis, particularly during the performance of aerosol-generating procedures (e.g., median sternotomy). Persons who handle bodies might be at risk for transmission of M. tuberculosis (77,78,171–177). Because certain procedures performed as part of an autopsy might generate infectious aerosols, special airborne precautions are required.

Autopsies should not be performed on bodies with suspected or confirmed TB disease without adequate protection for those performing the autopsy procedures. Settings in which autopsies are performed should meet or exceed the requirements of an AII room, if possible (see Environmental Controls), and the drawing in the American Conference of Governmental Industrial Hygienists(r) (ACGIH) Industrial Ventilation Manual VS-99-07 (178). Air should be exhausted to the outside of the building. Air-cleaning technologies (e.g., HEPA filtration or UVGI) can be used to increase the number of equivalent ACH (see Environmental Controls).

As an added administrative measure, when performing autopsies on bodies with suspected or confirmed TB disease, coordination between attending physicians and pathologists is needed to ensure proper infection control and specimen collection. The use of local exhaust ventilation should be considered to reduce exposures to infectious aerosols (e.g., when using a saw, including Striker saw). For HCWs performing an autopsy on a body with suspected or confirmed TB disease, at least N95 disposable respirators should be worn (see Respiratory Protection). Based on the risk assessment, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection).

After an autopsy is performed on a body with suspected or confirmed TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). If time delay is not feasible, the autopsy staff should continue to wear respirators while they are in the room.

Embalming Rooms

Tissue or organ removal in an embalming room performed on bodies with suspected or confirmed TB disease can pose a high risk for transmission of M. tuberculosis, particularly during the performance of aerosol-generating procedures. Persons who handle corpses might be at risk for transmission of M. tuberculosis (77,78,171–176). Because certain procedures performed as part of embalming might generate infectious aerosols, special airborne precautions are required.

Embalming involving tissue or organ removal should not be performed on bodies with suspected or confirmed TB disease without adequate protection for the persons performing the procedures. Settings in which these procedures are performed should meet or exceed the requirements of an AII room, if possible (see Environmental Controls), and the drawing in the ACGIH Industrial Ventilation Manual VS-99-07 (178). Air should be exhausted to the outside of the building. Air-cleaning technologies (e.g., HEPA filtration or UVGI) can be used to increase the number of equivalent ACH (see Environmental Controls). The use of local exhaust ventilation should be considered to reduce exposures to infectious aerosols (e.g., when using a saw, including Striker saw) and vapors from embalming fluids.

When HCWs remove tissues or organs from a body with suspected or confirmed TB disease, at least N95 disposable respirators should be worn (see Respiratory Protection). Based on the risk assessment, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection).

After tissue or organ removal is performed on a body with suspected or confirmed TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (see Environmental Controls). If time delay is not feasible, the staff should continue to wear respirators while in the room.

Outpatient Settings

Outpatient settings might include TB treatment facilities, dental-care settings, medical offices, ambulatory-care settings, and dialysis units. Environmental controls should be implemented based on the types of activities that are performed in the setting.

TB Treatment Facilities

TB treatment facilities might include TB clinics, infectious disease clinics, or pulmonary clinics. TB clinics and other settings in which patients with TB disease and LTBI are examined on a regular basis require special attention. The same principles of triage used in EDs and ambulatory-care settings (see Minimum Requirements) should be applied to TB treatment facilities. These principles include prompt identification, evaluation, and airborne precautions of patients with suspected or confirmed infectious TB disease.

All TB clinic staff, including outreach workers, should be screened for M. tuberculosis infection (Appendix C). Patients with suspected or confirmed infectious TB disease should be physically separated from all patients, but especially from those with HIV infection and other immunocompromising conditions that increase the likelihood of development of TB disease if infected. Immunosuppressed patients with suspected or confirmed infectious TB disease need to be physically separated from others to protect both the patient and others. Appointments should be scheduled to avoid exposing HIV-infected or otherwise severely immunocompromised persons to M. tuberculosis. Certain times of the day should be designated for appointments for patients with infectious TB disease or treat them in areas in which immunocompromised persons are not treated.

Persons with suspected or confirmed infectious TB disease should be promptly placed in an AII room to minimize exposure in the waiting room and other areas of the clinic, and they should be instructed to observe strict respiratory hygiene and cough etiquette procedures. Clinics that provide care for patients with suspected or confirmed infectious TB disease should have at least one AII room. The need for additional AII rooms should be based on the risk assessment for the setting.

All cough-inducing and aerosol-generating procedures should be performed using environmental controls (e.g., in a booth or an AII room) (see Environmental Controls). Patients should be left in the booth or AII room until coughing subsides. Another patient or HCW should not be allowed to enter the booth or AII room until sufficient time has elapsed for adequate removal of M. tuberculosis-contaminated air (see Environmental Controls). A respiratory-protection program should be implemented for all HCWs who work in the TB clinic and who enter AII rooms, visit areas in which persons with suspected or confirmed TB disease are located, or transport patients with suspected or confirmed TB disease in vehicles. When persons with suspected or confirmed infectious TB disease are in the TB clinic and not in an AII room, they should wear a surgical or procedure mask, if possible.

Medical Offices and Ambulatory-Care Settings

The symptoms of TB disease are usually symptoms for which patients might seek treatment in a medical office. Therefore, infectious TB disease could possibly be encountered in certain medical offices and ambulatory-care settings.

Because of the potential for M. tuberculosis transmission in medical offices and ambulatory-care settings, follow the general recommendations for management of patients with suspected or confirmed TB disease and the specific recommendations for EDs (see Intensive Care Units [ICUs]). The risk assessment may be used to determine the need for or selection of environmental controls and the frequency of testing HCWs for M. tuberculosis infection.

Dialysis Units

Certain patients with TB disease need chronic dialysis for treatment of ESRD (179–181). The incidence of TB disease and infection in patients with ESRD might be higher than in the general population (181–183) and might be compounded by the overlapping risks for ESRD and TB disease among patients with diabetes mellitus (39). In addition, certain dialysis patients or patients who are otherwise immunocompromised (e.g., patients with organ transplants) might be on immunosuppressive medications (162,183). Patients with ESRD who need chronic dialysis should have at least one test for M. tuberculosis infection to determine the need for treatment of LTBI. Annual re-screening is indicated if ongoing exposure of ESRD patients to M. tuberculosis is probable.

Hemodialysis procedures should be performed on hospitalized patients with suspected or confirmed TB disease in an AII room. Dialysis staff should use recommended respiratory protection, at least an N95 disposable respirator. Patients with suspected or confirmed TB disease who need chronic hemodialysis might need referral to a hospital or other setting with the ability to perform dialysis procedures in an AII room until the patient is no longer infectious or another diagnosis is made. Certain antituberculosis medications are prescribed differently for hemodialysis patients (31).

Dental-Care Settings

The generation of droplet nuclei containing M. tuberculosis as a result of dental procedures has not been demonstrated (184). Nonetheless, oral manipulations during dental procedures could stimulate coughing and dispersal of infectious particles. Patients and dental HCWs share the same air space for varying periods, which contributes to the potential for transmission of M. tuberculosis in dental settings (185). For example, during primarily routine dental procedures in a dental setting, MDR TB might have been transmitted between two dental workers (186).

To prevent the transmission of M. tuberculosis in dental-care settings, certain recommendations should be followed (187,188). Infection-control policies for each dental health-care setting should be developed, based on the community TB risk assessment (Appendix B), and should be reviewed annually, if possible. The policies should include appropriate screening for LTBI and TB disease for dental HCWs, education on the risk for transmission to the dental HCWs, and provisions for detection and management of patients who have suspected or confirmed TB disease.

When taking a patient's initial medical history and at periodic updates, dental HCWs should routinely document whether the patient has symptoms or signs of TB disease. If urgent dental care must be provided for a patient who has suspected or confirmed infectious TB disease, dental care should be provided in a setting that meets the requirements for an AII room (see Environmental Controls). Respiratory protection (at least N95 disposable respirator) should be used while performing procedures on such patients.

In dental health-care settings that routinely provide care to populations at high risk for TB disease, using engineering controls (e.g., portable HEPA units) similar to those used in waiting rooms or clinic areas of health-care settings with a comparable community-risk profile might be beneficial.

During clinical assessment and evaluation, a patient with suspected or confirmed TB disease should be instructed to observe strict respiratory hygiene and cough etiquette procedures (122). The patient should also wear a surgical or procedure mask, if possible. Non-urgent dental treatment should be postponed, and these patients should be promptly referred to an appropriate medical setting for evaluation of possible infectiousness. In addition, these patients should be kept in the dental health-care setting no longer than required to arrange a referral.

Nontraditional Facility-Based Settings

Nontraditional facility-based settings include EMS, medical settings in correctional facilities, home-based health-care and outreach settings, long-term–care settings (e.g., hospices and skilled nursing facilities), and homeless shelters. Environmental controls should be implemented based on the types of activities that are performed in the setting.

TB is more common in the homeless population than in the general population (189–192). Because persons who visit homeless shelters frequently share exposure and risk characteristics of TB patients who are treated in outpatient clinics, homeless shelters with clinics should observe the same TB infection-control measures as outpatient clinics. ACET has developed recommendations to assist health-care providers, health departments, shelter operators and workers, social service agencies, and homeless persons to prevent and control TB in this population (189).

Emergency Medical Services (EMS)

Although the overall risk is low (193), documented transmission of M. tuberculosis has occurred in EMS occupational settings (194), and approaches to reduce this risk have been described (193,195). EMS personnel should be included in a comprehensive screening program to test for M. tuberculosis infection and provide baseline screening and follow-up testing as indicated by the risk classification of the setting. Persons with suspected or confirmed infectious TB disease who are transported in an ambulance should wear a surgical or procedure mask, if possible, and drivers, HCWs, and other staff who are transporting the patient might consider wearing an N95 respirator.

The ambulance ventilation system should be operated in the nonrecirculating mode, and the maximum amount of outdoor air should be provided to facilitate dilution. If the vehicle has a rear exhaust fan, use this fan during transport. If the vehicle is equipped with a supplemental recirculating ventilation unit that passes air through HEPA filters before returning it to the vehicle, use this unit to increase the number of ACH (188). Air should flow from the cab (front of vehicle), over the patient, and out the rear exhaust fan. If an ambulance is not used, the ventilation system for the vehicle should bring in as much outdoor air as possible, and the system should be set to nonrecirculating. If possible, physically isolate the cab from the rest of the vehicle, and place the patient in the rear seat (194).

EMS personnel should be included in the follow-up contact investigations of patients with infectious TB disease. The Ryan White Comprehensive AIDS Resource Emergency Act of 1990 (Public law 101–381) mandates notification of EMS personnel after they have been exposed to a patient with suspected or confirmed infectious TB disease (Title 42 U.S. Code 1994) (http://hab.hrsa.gov/data2/adap/introduction.htm).

Medical Settings in Correctional Facilities

TB is a substantial health concern in correctional facilities; employees and inmates are at high risk (105,196–205). TB outbreaks in correctional facilities can lead to transmission in surrounding communities (201,206,207). ACET recommends that all correctional facilities have a written TB infection-control plan (196), and multiple studies indicate that screening correctional employees and inmates is a vital TB control measure (204,208,209).

The higher risk for M. tuberculosis transmission in health-care settings in correctional facilities (including jails and prisons) is a result of the disproportionate number of inmates with risk factors for TB infection and TB disease (203,210). Compared with the general population, TB prevalence is higher among inmates and is associated with a higher prevalence of HIV infection (197), increased illicit substance use, lower socioeconomic status (201), and their presence in settings that are at high risk for transmission of M. tuberculosis.

A TB infection-control plan should be developed specifically for that setting, even if the institution is part of a multifacility system (196,211). Medical settings in correctional facilities should be classified as at least medium risk; therefore, all correctional facility health-care personnel and other staff, including correctional officers should be screened for TB at least annually (201,203,208).

Correctional facilities should collaborate with the local or state health department to decide on TB contact investigations and discharge planning (105,212) and to provide TB training and education to inmates and employees (196). Corrections staff should be educated regarding symptoms and signs of TB disease and encouraged to facilitate prompt evaluation of inmates with suspected infectious TB disease (206).

At least one AII room should be available in correctional facilities. Any inmate with suspected or confirmed infectious TB disease should be placed in an AII room immediately or transferred to a setting with an AII room; base the number of additional AII rooms needed on the risk assessment for the setting. Sputum samples should be collected in sputum induction booths or AII rooms, not in inmates' cells. Sputum collection can also be performed safely outside, away from other persons, windows, and ventilation intakes.

Inmates with suspected or confirmed infectious TB disease who must be transported outside an AII room for medically essential procedures should wear a surgical or procedure mask during transport, if possible. If risk assessment indicates the need for respiratory protection, drivers, medical or security staff, and others who are transporting patients with suspected or confirmed infectious TB disease in an enclosed vehicle should consider wearing an N95 disposable respirator.

A respiratory-protection program, including training, education, and fit-testing in the correctional facility's TB infection-control program should be implemented. Correctional facilities should maintain a tracking system for inmate TB screening and treatment and establish a mechanism for sharing this information with state and local health departments and other correctional facilities (196,201). Confidentiality of inmates should be ensured during screening for symptoms or signs of TB disease and risk factors.

Home-Based Health-Care and Outreach Settings

Transmission of M. tuberculosis has been documented in staff who work in home-based health-care and outreach settings (213,214). The setting's infection-control plan should include training that reminds HCWs who provide medical services in the homes of patients or other outreach settings of the importance of early evaluation of symptoms or signs of TB disease for early detection and treatment of TB disease. Training should also include the role of the HCW in educating patients regarding the importance of reporting symptoms or signs of TB disease and the importance of reporting any adverse effects to treatment for LTBI or TB disease.

HCWs who provide medical services in the homes of patients with suspected or confirmed TB disease can help prevent transmission of M. tuberculosis by 1) educating patients and other household members regarding the importance of taking medications as prescribed, 2) facilitating medical evaluation of symptoms or signs of TB disease, and 3) administering DOT, including DOT for treatment of LTBI whenever feasible.

HCWs who provide medical services in the homes of patients should not perform cough-inducing or aerosol-generating procedures on patients with suspected or confirmed infectious TB disease, because recommended infection controls probably will not be in place. Sputum collection should be performed outdoors, away from other persons, windows, and ventilation intakes.

HCWs who provide medical services in the homes of patients with suspected or confirmed infectious TB disease should instruct TB patients to observe strict respiratory hygiene and cough etiquette procedures. HCWs who enter homes of persons with suspected or confirmed infectious TB disease or who transport such persons in an enclosed vehicle should consider wearing at least an N95 disposable respirator (see Respiratory Protection).

Long-Term–Care Facilities (LTCFs)

TB poses a health risk to patients, HCWs, visitors, and volunteers in LTCFs (e.g., hospices and skilled nursing facilities) (215,216). Transmission of M. tuberculosis has occurred in LTCF (217–220), and pulmonary TB disease has been documented in HIV-infected patients and other immunocompromised persons residing in hospices (218,221,222). New employees and residents to these settings should receive a symptom screen and possibly a test for M. tuberculosis infection (see TB Risk Assessment Worksheet).

LTCFs must have adequate administrative and environmental controls, including airborne precautions capabilities and a respiratory-protection program, if they accept patients with suspected or confirmed infectious TB disease. The setting should have 1) a written protocol for the early identification of patients with symptoms or signs of TB disease and 2) procedures for referring these patients to a setting where they can be evaluated and managed. Patients with suspected or confirmed infectious TB disease should not stay in LTCFs unless adequate administrative and environmental controls and a respiratory-protection program are in place. Persons with TB disease who are determined to be noninfectious can remain in the LTCF and do not need to be in an AII room.

Training and Educating HCWs

HCW training and education regarding infection with M. tuberculosis and TB disease is an essential part of administrative controls in a TB surveillance or infection-control program. Training physicians and nurse managers is especially essential because of the leadership role they frequently fulfill in infection control. HCW training and education can increase adherence to TB infection-control measures. Training and education should emphasize the increased risks posed by an undiagnosed person with TB disease in a health-care setting and the specific measures to reduce this risk. HCWs receive various types of training; therefore, combining training for TB infection control with other related trainings might be preferable.

Initial TB Training and Education

The setting should document that all HCWs, including physicians, have received initial TB training relevant to their work setting and additional occupation-specific education. The level and detail of baseline training will vary according to the responsibilities of the HCW and the risk classification of the setting.

Educational materials on TB training are available from various sources at no cost in printed copy, on videotape (223), on compact discs, and the Internet. The local or state health department should have access to additional materials and resources and might be able to help develop a setting-specific TB education program. Suggested components of a baseline TB training program for HCWs have been described previously. CDC's TB website provides information regarding training and education materials (http://www.cdc.gov/tb). Additional training and education materials are available on CDC's TB Education and Training Resources website (http://www.findtbresources.org) and on other TB-related websites and resources (Appendix E).

Physicians, trainees, students, and other HCWs who work in a health-care setting but do not receive payment from that setting should receive baseline training in TB infection-control policies and practices, the TB screening program, and procedures for reporting an M. tuberculosis infection test conversion or diagnosis of TB disease. Initial TB training should be provided before the HCW starts working.

Follow-Up TB Training and Education

All settings should conduct an annual evaluation of the need for follow-up training and education for HCWs based on the number of untrained and new HCWs, changes in the organization and services of the setting, and availability of new TB infection-control information.

If a potential or known exposure to M. tuberculosis occurs in the setting, prevention and control measures should include retraining HCWs in the infection-control procedures established to prevent the recurrence of exposure. If a potential or known exposure results in a newly recognized positive TST or BAMT result, test conversion, or diagnosis of TB disease, education should include information on 1) transmission of M. tuberculosis, 2) noninfectiousness of HCWs with LTBI, and 3) potential infectiousness of HCWs with TB disease.

OSHA requires annual respiratory-protection training for HCWs who use respiratory devices (see Respiratory Protection). HCWs in settings with a classification of potential ongoing transmission should receive additional training and education on 1) symptoms and signs of TB disease, 2) M. tuberculosis transmission, 3) infection-control policies, 4) importance of TB screening for HCWs, and 5) responsibilities of employers and employees regarding M. tuberculosis infection test conversion and diagnosis of TB disease.

TB Infection-Control Surveillance

HCW Screening Programs for TB Support Surveillance and Clinical Care

TB screening programs provide critical information for caring for individual HCWs and information that facilitates detection of M. tuberculosis transmission. The screening program consists of four major components: 1) baseline testing for M. tuberculosis infection, 2) serial testing for M. tuberculosis infection, 3) serial screening for symptoms or signs of TB disease, and 4) TB training and education.

Surveillance data from HCWs can protect both HCWs and patients. Screening can prevent future transmission by identifying lapses in infection control and expediting treatment for persons with LTBI or TB disease. Tests to screen for M. tuberculosis infection should be administered, interpreted, and recorded according to procedures in this report (see Supplement, Diagnostic Procedures for LTBI and TB Disease). Protection of privacy and maintenance of confidentiality of HCW test results should be ensured. Methods to screen for infection with M. tuberculosis are available (30,31,39).

Baseline Testing for M. tuberculosis Infection

Baseline testing for M. tuberculosis infection is recommended for all newly hired HCWs, regardless of the risk classification of the setting and can be conducted with the TST or BAMT. Baseline testing is also recommended for persons who will receive serial TB screening (e.g., residents or staff of correctional facilities or LTCFs) (39,224). Certain settings, with the support of the infection-control committee, might choose not to perform baseline or serial TB screening for HCWs who will never be in contact with or have shared air space with patients who have TB disease (e.g., telephone operators who work in a separate building from patients) or who will never be in contact with clinical specimens that might contain M. tuberculosis.

Baseline test results 1) provide a basis for comparison in the event of a potential or known exposure to M. tuberculosis and 2) facilitate the detection and treatment of LTBI or TB disease in an HCW before employment begins and reduces the risk to patients and other HCWs. If TST is used for baseline testing, two-step testing is recommended for HCWs whose initial TST results are negative (39,224). If the first-step TST result is negative, the second-step TST should be administered 1–3 weeks after the first TST result was read. If either 1) the baseline first-step TST result is positive or 2) the first-step TST result is negative but the second-step TST result is positive, TB disease should be excluded, and if it is excluded, then the HCW should be evaluated for treatment of LTBI. If the first and second-step TST results are both negative, the person is classified as not infected with M. tuberculosis.

If the second test result of a two-step TST is not read within 48–72 hours, administer a TST as soon as possible (even if several months have elapsed) and ensure that the result is read within 48–72 hours (39). Certain studies indicate that positive TST reactions might still be measurable from 4–7 days after testing (225,226). However, if a patient fails to return within 72 hours and has a negative test result, the TST should be repeated (42).

A positive result to the second step of a baseline two-step TST is probably caused by boosting as opposed to recent infection with M. tuberculosis. These responses might result from remote infections with M. tuberculosis, infection with an NTM (also known as MOTT), or previous BCG vaccination. Two-step testing will minimize the possibility that boosting will lead to an unwarranted suspicion of transmission of M. tuberculosis with subsequent testing. A second TST is not needed if the HCW has a documented TST result from any time during the previous 12 months (see Baseline Testing for M. tuberculosis Infection After TST Within the Previous 12 Months).

A positive TST reaction as a result of BCG wanes after 5 years. Therefore, HCWs with previous BCG vaccination will frequently have a negative TST result (74,227–232). Because HCWs with a history of BCG are frequently from high TB-prevalence countries, positive test results for M. tuberculosis infection in HCWs with previous BCG vaccination should be interpreted as representing infection with M. tuberculosis (74,227–233). Although BCG reduces the occurrence of severe forms of TB disease in children and overall might reduce the risk for progression from LTBI to TB disease (234,235), BCG is not thought to prevent M. tuberculosis infection (236). Test results for M. tuberculosis infection for HCWs with a history of BCG should be interpreted by using the same diagnostic cut points used for HCWs without a history of BCG vaccination.

BAMT does not require two-step testing and is more specific than skin testing. BAMT that uses M. tuberculosis-specific antigens (e.g., QFT-G) are not expected to result in false-positive results in persons vaccinated with BCG. Baseline test results should be documented, preferably within 10 days of HCWs starting employment.

Baseline Testing for M. tuberculosis Infection After TST Within the Previous 12 Months

A second TST is not needed if the HCW has a documented TST result from any time during the previous 12 months. If a newly employed HCW has had a documented negative TST result within the previous 12 months, a single TST can be administered in the new setting (Box 1). This additional TST represents the second stage of two-step testing. The second test decreases the possibility that boosting on later testing will lead to incorrect suspicion of transmission of M. tuberculosis in the setting.

A recent TST (performed in ≤12 months) is not a contraindication to a subsequent TST unless the test was associated with severe ulceration or anaphylactic shock, which are substantially rare adverse events (30,237–239). Multiple TSTs are safe and do not increase the risk for a false-positive result or a TST conversion in persons without infection with mycobacteria (39).

Baseline Documentation of a History of TB Disease, a Previously Positive Test Result for M. tuberculosis Infection, or Completion of Treatment for LTBI or TB Disease

Additional tests for M. tuberculosis infection do not need to be performed for HCWs with a documented history of TB disease, documented previously positive test result for M. tuberculosis infection, or documented completion of treatment for LTBI or TB disease. Documentation of a previously positive test result for M. tuberculosis infection can be substituted for a baseline test result if the documentation includes a recorded TST result in millimeters (or BAMT result), including the concentration of cytokine measured (e.g., IFN-γ). All other HCWs should undergo baseline testing for M. tuberculosis infection to ensure that the test result on record in the setting has been performed and measured using the recommended diagnostic the recommended procedures (see Supplement, Diagnostic Procedures for LTBI and TB Disease).

A recent TST (performed in ≤12 months) is not a contraindication to the administration of an additional test unless the TST was associated with severe ulceration or anaphylactic shock, which are substantially rare adverse events (30,237,238). However, the recent test might complicate interpretation of subsequent test results because of the possibility of boosting.

Serial Follow-Up of TB Screening and Testing for M. tuberculosis Infection

The need for serial follow-up screening for groups of HCWs with negative test results for M. tuberculosis infection is an institutional decision that is based on the setting's risk classification. This decision and changes over time based on updated risk assessments should be official and documented. If a serial follow-up screening program is required, the risk assessment for the setting (Appendix B) will determine which HCWs should be included in the program and the frequency of screening. Two-step TST testing should not be performed for follow-up testing.

If possible, stagger follow-up screening (rather than testing all HCWs at the same time each year) so that all HCWs who work in the same area or profession are not tested in the same month. Staggered screening of HCWs (e.g., on the anniversary of their employment or on their birthdays) increases opportunities for early recognition of infection-control problems that can lead to conversions in test results for M. tuberculosis infection. Processing aggregate analysis of TB screening data on a periodic regular basis is important for detecting problems.

HCWs with a Newly Recognized Positive Test Result for M. tuberculosis Infection or Symptoms or Signs of TB Disease

Clinical Evaluation

Any HCW with a newly recognized positive test result for M. tuberculosis infection, test conversion, or symptoms or signs of TB disease should be promptly evaluated. The evaluation should be arranged with employee health, the local or state health department, or a personal physician. Any physicians who evaluate HCWs with suspected TB disease should be familiar with current diagnostic and therapeutic guidelines for LTBI and TB disease (31,39).

The definitions for positive test results for M. tuberculosis infection and test conversion in HCWs are included in this report (see Supplement, Diagnostic Procedures for LTBI and TB Disease). Symptoms of disease in the lung, pleura, or airways, and the larynx include coughing for ≥3 weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum or hemoptysis, hoarseness, fever, fatigue, or chest pain. The evaluation should include a clinical examination and symptom screen (a procedure used during a clinical evaluation in which patients are asked if they have experienced any symptoms or signs of TB disease), chest radiograph, and collection of sputum specimens.

If TB disease is diagnosed, begin antituberculosis treatment immediately, according to published guidelines (31). The diagnosing clinician (who might not be a physician with the institution's infection-control program) should notify the local or state health department in accordance with disease reporting laws, which generally specify a 24-hour time limit.

If TB disease is excluded, offer the HCW treatment for LTBI in accordance with published guidelines (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease [39,240]). If the HCW has already completed treatment for LTBI and is part of a TB screening program, instead of participating in serial skin testing, the HCW should be monitored for symptoms of TB disease and should receive any available training, which should include information on the symptoms of TB disease and instructing the HCW to report any such symptoms immediately to occupational health. In addition, annual symptom screens should be performed, which can be administered as part of other HCW screening and education efforts. Treatment for LTBI should be offered to HCWs who are eligible (39).

HCWs with a previously negative test result who have an increase of ≥10 mm induration when examined on follow-up testing probably have acquired M. tuberculosis infection and should be evaluated for TB disease. When disease is excluded, HCWs should be treated for LTBI unless medically contraindicated (39,240).

Chest Radiography

HCWs with a baseline positive or newly positive TST or BAMT result should receive one chest radiograph to exclude a diagnosis of TB disease (or an interpretable copy within a reasonable time frame, such as 6 months). After this baseline chest radiograph is performed and the result is documented, repeat radiographs are not needed unless symptoms or signs of TB disease develop or a clinician recommends a repeat chest radiograph (39,116). Instead of participating in serial testing for M. tuberculosis infection, HCWs with a positive test result for M. tuberculosis infection should receive a symptom screen. The frequency of this symptom screen should be determined by the risk classification for the setting.

Serial follow-up chest radiographs are not recommended for HCWs with documentation of a previously positive test result for M. tuberculosis infection, treatment for LTBI or TB disease, or for asymptomatic HCWs with negative test results for M. tuberculosis infection. HCWs who have a previously positive test result for M. tuberculosis infection and who change jobs should carry documentation of a baseline chest radiograph result (and the positive test result for M. tuberculosis infection) to their new employers.

Workplace Restrictions

HCWs with a baseline positive or newly positive test result for M. tuberculosis infection should receive one chest radiograph result to exclude TB disease (or an interpretable copy within a reasonable time frame, such as 6 months).

HCWs with confirmed infectious pulmonary, laryngeal, endobroncheal, or tracheal TB disease, or a draining TB skin lesion pose a risk to patients, HCWs, and others. Such HCWs should be excluded from the workplace and should be allowed to return to work when the following criteria have been met: 1) three consecutive sputum samples (109–112) collected in 8–24-hour intervals that are negative, with at least one sample from an early morning specimen (because respiratory secretions pool overnight); 2) the person has responded to antituberculosis treatment that will probably be effective (can be based on susceptibility results); and 3) the person is determined to be noninfectious by a physician knowledgeable and experienced in managing TB disease (see Supplements, Estimating the Infectiousness of a TB Patient; Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease).

HCWs with extrapulmonary TB disease usually do not need to be excluded from the workplace as long as no involvement of the respiratory track has occurred. They can be confirmed as noninfectious and can continue to work if documented evidence is available that indicates that concurrent pulmonary TB disease has been excluded.

HCWs receiving treatment for LTBI can return to work immediately. HCWs with LTBI who cannot take or do not accept or complete a full course of treatment for LTBI should not be excluded from the workplace. They should be counseled regarding the risk for developing TB disease and instructed to report any TB symptoms immediately to the occupational health unit.

HCWs who have a documented positive TST or BAMT result and who leave employment should be counseled again, if possible, regarding the risk for developing TB disease and instructed to seek prompt evaluation with the local health department or their primary care physician if symptoms of TB disease develop. Consider mailing letters to former HCWs who have LTBI. This information should be recorded in the HCWs' employee health record when they leave employment.

Asymptomatic HCWs with a baseline positive or newly positive TST or BAMT result do not need to be excluded from the workplace. Treatment for LTBI should be considered in accordance with CDC guidelines (39).

Identification of Source Cases and Recording of Drug-Susceptibility Patterns

If an HCW experiences a conversion in a test result for M. tuberculosis infection, evaluate the HCW for a history of suspected or known exposure to M. tuberculosis to determine the potential source. When the source case is identified, also identify the drug susceptibility pattern of the M. tuberculosis isolate from the source. The drug-susceptibility pattern should be recorded in the HCW's medical or employee health record to guide the treatment of LTBI or TB disease, if indicated.

HCWs with Medical Conditions Associated with Increased Risk for Progression to TB Disease

In settings in which HCWs are severely immunocompromised, additional precautions must be taken. HIV infection is the highest risk factor for progression from LTBI to TB disease (22,39,42,49). Other immunocompromising conditions, including diabetes mellitus, certain cancers, and certain drug treatments, also increase the risk for rapid progression from LTBI to TB disease. TB disease can also adversely affect the clinical course of HIV infection and acquired immunodeficiency syndrome (AIDS) and can complicate HIV treatment (31,39,53).

Serial TB screening beyond that indicated by the risk classification for the setting is not indicated for persons with the majority of medical conditions that suppress the immune system or otherwise increase the risk for infection with M. tuberculosis progressing to TB disease (58). However, consideration should be given to repeating the TST for HIV-infected persons whose initial TST result was negative and whose immune function has improved in response to highly active antiretroviral therapy (HAART) (i.e., those whose CD4-T lymphocyte count has increased to >200 cells/mL).

All HCWs should, however, be encouraged during their initial TB training to determine if they have such a medical condition and should be aware that receiving medical treatment can improve cell-mediated immunity. HCWs should be informed concerning the availability of counseling, testing, and referral for HIV (50,51). In addition, HCWs should know whether they are immunocompromised, and they should be aware of the risks from exposure to M. tuberculosis (1). In certain cases, reassignment to areas in which exposure is minimized or nonexistent might be medically advisable or desirable.

Immunocompromised HCWs should have the option of an assignment in an area or activity where the risk for exposure to M. tuberculosis is low. This choice is a personal decision for the immunocompromised HCW (241) (http://www.eeoc.gov/laws/ada.html). Health-care settings should provide education and follow infection-control recommendations (70).

Information provided by HCWs regarding their immune status and request for voluntary work assignments should be treated confidentially, according to written procedures on the confidential handling of such information. All HCWs should be made aware of these procedures at the time of employment and during initial TB training and education.

Problem Evaluation

Contact investigations might be initiated in response to 1) conversions in test results in HCWs for M. tuberculosis infection, 2) diagnosis of TB disease in an HCW, 3) suspected person-to-person transmission of M. tuberculosis, 4) lapses in TB infection-control practices that expose HCWs and patients to M. tuberculosis, or 5) possible TB outbreaks identified using automated laboratory systems (242). In these situations, the objectives of a contact investigation might be to 1) determine the likelihood that transmission of M. tuberculosis has occurred; 2) determine the extent of M. tuberculosis transmission; 3) identify persons who were exposed, and, if possible, the sources of potential transmission; 4) identify factors that could have contributed to transmission, including failure of environmental infection-control measures, failure to follow infection-control procedures, or inadequacy of current measures or procedures; 5) implement recommended interventions; 6) evaluate the effectiveness of the interventions; and 7) ensure that exposure to M. tuberculosis has been terminated and that the conditions leading to exposure have been eliminated.

Earlier recognition of a setting in which M. tuberculosis transmission has occurred could be facilitated through innovative approaches to TB contact investigations (e.g., network analysis and genetic typing of isolates). Network analysis makes use of information (e.g., shared locations within a setting that might not be collected in traditional TB contact investigations) (45). This type of information might be useful during contact investigations involving hospitals or correctional settings to identify any shared wards, hospital rooms, or cells. Genotyping of isolates is universally available in the United States and is a useful adjunct in the investigation of M. tuberculosis transmission (44,89,243,244). Because the situations prompting an investigation are likely to vary, investigations should be tailored to the individual circumstances. Recommendations provide general guidance for conducting contact investigations (34,115).

General Recommendations for Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs

A test conversion might need to be reported to the health department, depending on state and local regulations. Problem evaluation during contact investigations should be accomplished through cooperation between infection-control personnel, occupational health, and the local or state TB-control program. If a test conversion in an HCW is detected as a result of serial screening and the source is not apparent, conduct a source case investigation to determine the probable source and the likelihood that transmission occurred in the health-care setting (115).

Lapses in TB infection control that might have contributed to the transmission of M. tuberculosis should be corrected. Test conversions and TB disease among HCWs should be recorded and reported, according to OSHA requirements (http://www.osha.gov/recordkeeping). Consult Recording and Reporting Occupational Injuries and Illness (OSHA standard 29 Code of Federal Regulations [CFR], 1904) to determine recording and reporting requirements (245).

Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Probable Source Outside the Health-Care Setting

If a test conversion in an HCW is detected and exposure outside the health-care setting has been documented by the corresponding local or state health department, terminate the investigation within the health-care setting.

Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Known Source in the Health-Care Setting

An investigation of a test conversion should be performed in collaboration with the local or state health department. If a conversion in an HCW is detected and the HCW's history does not document exposure outside the health-care setting but does identify a probable source in the setting, the following steps should be taken: 1) identify and evaluate close contacts of the suspected source case, including other patients and visitors; 2) determine possible reasons for the exposure; 3) implement interventions to correct the lapse(s) in infection control; and 4) immediately screen HCWs and patients if they were close contacts to the source case. For exposed HCWs and patients in a setting that has chosen to screen for infection with M. tuberculosis by using the TST, the following steps should be taken:

  • administer a symptom screen;
  • administer a TST to those who had previously negative TST results; baseline two-step TST should not be performed in contact investigations;
  • repeat the TST and symptom screen 8–10 weeks after the end of exposure, if the initial TST result is negative (33);
  • administer a symptom screen, if the baseline TST result is positive;
  • promptly evaluate (including a chest radiograph) the exposed person for TB disease, if the symptom screen or the initial or 8–10-week follow-up TST result is positive; and
  • conduct additional medical and diagnostic evaluation (which includes a judgment about the extent of exposure) for LTBI, if TB disease is excluded.

If no additional conversions in the test results for M. tuberculosis infection are detected in the follow-up testing, terminate the investigation. If additional conversions in the tests for M. tuberculosis infection are detected in the follow-up testing, transmission might still be occurring, and additional actions are needed: 1) implement a classification of potential ongoing transmission for the specific setting or group of HCWs; 2) the initial cluster of test conversions should be reported promptly to the local or state health department; 3) possible reasons for exposure and transmission should be reassessed and 4) the degree of adherence to the interventions implemented should be evaluated.

Testing for M. tuberculosis infection should be repeated 8–10 weeks after the end of exposure for HCW contacts who previously had negative test results, and the circle of contacts should be expanded to include other persons who might have been exposed. If no additional TST conversions are detected on the second round of follow-up testing, terminate the investigation. If additional TST conversions are detected on the second round of follow-up testing, maintain a classification of potential ongoing transmission and consult the local or state health department or other persons with expertise in TB infection control for assistance.

The classification of potential ongoing transmission should be used as a temporary classification only. This classification warrants immediate investigation and corrective steps. After determination has been made that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Investigating a Conversion of a Test Result for M. tuberculosis Infection in an HCW with an Unknown Exposure

If a test conversion in an HCW is detected and the HCW's history does not document exposure outside the health-care setting and does not identify a probable source of exposure in the setting, additional investigation to identify a probable source in the health-care setting is warranted.

If no source case is identified, estimate the interval during which the HCW might have been infected. The interval is usually 8–10 weeks before the most recent negative test result through 2 weeks before the first positive test result. Laboratory and infection-control records should be reviewed to identify all patients (and any HCWs) who have had suspected or confirmed infectious TB disease and who might have transmitted M. tuberculosis to the HCW. If the investigation identifies a probable source, identify and evaluate contacts of the suspected source. Close contacts should be the highest priority for screening.

The following steps should be taken in a setting that uses TST or BAMT to screen for M. tuberculosis: 1) administer a symptom screen and the test routinely used in the setting (i.e., TST or BAMT) to persons who previously had negative results; 2) if the initial result is negative, the test and symptom screen should be repeated 8–10 weeks after the end of exposure; 3) if the symptom screen, the first test result, or the 8–10-week follow-up test result is positive, the presumed exposed person should be promptly evaluated for TB disease, including the use of a chest radiograph; and 4) if TB disease is excluded, additional medical and diagnostic evaluation for LTBI is needed, which includes a judgment regarding the extent of exposure (see Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Known Source in the Health-Care Setting).

Investigations That Do Not Identify a Probable Source

If serial TB screening is performed in the setting, review the results of screening of other HCWs in the same area of the health-care setting or same occupational group. If serial TB screening is not performed in the setting or if insufficient numbers of recent results are available, conduct additional TB screening of other HCWs in the same area or occupational group. If the review and screening yield no additional test conversions, and no evidence to indicate health-care–associated transmission exists, then the investigation should be terminated.

Whether HCW test conversions resulted from exposure in the setting or elsewhere or whether true infection with M. tuberculosis has even occurred is uncertain. However, the absence of other data implicating health-care–associated transmission suggests that the conversion could have resulted from 1) unrecognized exposure to M. tuberculosis outside the health-care setting; 2) cross reactivity with another antigen (e.g., BCG or nontuberculous mycobacteria); or 3) errors in applying, reading, or interpreting the test result for M. tuberculosis infection. If the review and screening identify additional test conversions, health-care–associated transmission is more probable.

Evaluation of the patient identification process, TB infection-control policies and practices, and environmental controls to identify lapses that could have led to exposure and transmission should be conducted. If no problems are identified, a classification of potential ongoing transmission should be applied, and the local or state health department or other persons with expertise in TB infection control should be consulted for assistance. If problems are identified, implement recommended interventions and repeat testing for M. tuberculosis infection 8–10 weeks after the end of exposure for HCWs with negative test results. If no additional test conversions are detected in the follow-up testing, terminate the investigation.

Conversions in Test Results for M. tuberculosis Infection Detected in Follow-Up Testing

In follow-up testing, a classification of potential ongoing transmission should be maintained. Possible reasons for exposure and transmission should be reassessed, and the appropriateness of and degree of adherence to the interventions implemented should be evaluated. For HCWs with negative test results, repeat testing for M. tuberculosis infection 8–10 weeks after the end of exposure. The local or state health department or other persons with expertise in TB infection control should be consulted.

If no additional conversions are detected during the second round of follow-up testing, terminate the investigation. If additional conversions are detected, continue a classification of potential ongoing transmission and consult the local or state health department or other persons with expertise in TB infection control.

The classification of potential ongoing transmission should be used as a temporary classification only. This classification warrants immediate investigation and corrective steps. After a determination that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Investigating a Case of TB Disease in an HCW

Occupational health services and other physicians in the setting should have procedures for immediately notifying the local administrators or infection-control personnel if an HCW is diagnosed with TB disease so that a problem evaluation can be initiated. If an HCW is diagnosed with TB disease and does not have a previously documented positive test result for M. tuberculosis infection, conduct an investigation to identify the probable sources and circumstances for transmission (see General Recommendations for Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs). If an HCW is diagnosed with TB disease, regardless of previous test result status, an additional investigation must be conducted to ascertain whether the disease was transmitted from this HCW to others, including other HCWs, patients, and visitors.

The potential infectiousness of the HCW, if potentially infectious, and the probable period of infectiousness (see Contact Investigations) should be determined. For HCWs with suspected or confirmed infectious TB disease, conduct an investigation that includes 1) identification of contacts (e.g., other HCWs, patients, and visitors), 2) evaluation of contacts for LTBI and TB disease, and 3) notification of the local or state health department for consultation and investigation of community contacts who were exposed outside the health-care setting.

M. tuberculosis genotyping should be performed so that the results are promptly available. Genotyping results are useful adjuncts to epidemiologically based public health investigations of contacts and possible source cases (especially in determining the role of laboratory contamination) (89,166,243,246–261). When confidentiality laws prevent the local or state health department from communicating information regarding a patient's identity, health department staff should work with hospital staff and legal counsel, and the HCW to determine how the hospital can be notified without breaching confidentiality.

Investigating Possible Patient-to-Patient Transmission of M. tuberculosis

Information concerning TB cases among patients in the setting should be routinely recorded for risk classification and risk assessment purposes. Documented information by location and date should include results of sputum smear and culture, chest radiograph, drug-susceptibility testing, and adequacy of infection-control measures.

Each time a patient with suspected or confirmed TB disease is encountered in a health-care setting, an assessment of the situation should be made and the focus should be on 1) a determination of infectiousness of the patient, 2) confirmation of compliance with local public health reporting requirements (including the prompt reporting of a person with suspected TB disease as required), and 3) assessment of the adequacy of infection control.

A contact investigation should be initiated in situations where infection control is inadequate and the patient is infectious. Patients with positive AFB sputum smear results are more infectious than patients with negative AFB sputum smear results, but the possibility exists that patients with negative sputum smear results might be infectious (262). Patients with negative AFB sputum smear results but who undergo aerosol-generating or aerosol-producing procedures (including bronchoscopy) without adequate infection-control measures create a potential for exposure. All investigations should be conducted in consultation with the local public health department.

If serial surveillance of these cases reveals one of the following conditions, patient-to-patient transmission might have occurred, and a contact investigation should be initiated:

  • A high proportion of patients with TB disease were admitted to or examined in the setting during the year preceding onset of their TB disease, especially when TB disease is identified in patients who were otherwise unlikely to be exposed to M. tuberculosis.
  • An increase occurred in the number of TB patients diagnosed with drug-resistant TB, compared with the previous year.
  • Isolates from multiple patients had identical and characteristic drug susceptibility or DNA fingerprint patterns.

Surveillance of TB Cases in Patients Indicates Possible Patient-to-Patient Transmission of M. tuberculosis

Health-care settings should collaborate with the local or state health department to conduct an investigation. For settings in which HCWs are serially tested for M. tuberculosis infection, review HCW records to determine whether an increase in the number of conversions in test results for M. tuberculosis infection has occurred. Patient surveillance data and medical records should be reviewed for additional cases of TB disease. Settings should look for possible exposures from previous or current admissions that might have exposed patients with newly diagnosed TB disease to other patients with TB disease, determining if the patients were admitted to the same room or area, or if they received the same procedure or went to the same treatment area on the same day.

If the investigation suggests that transmission has occurred, possible causes of transmission of M. tuberculosis (e.g., delayed diagnosis of TB disease, institutional barriers to implementing timely and correct airborne precautions, and inadequate environmental controls) should be evaluated. Possible exposure to other patients or HCWs should be determined, and if exposure has occurred, these persons should be evaluated for LTBI and TB disease (i.e., test for M. tuberculosis infection and administer a symptom screen).

If the local or state health department was not previously contacted, settings should notify the health department so that a community contact investigation can be initiated, if necessary. The possibility of laboratory errors in diagnosis or the contamination of bronchoscopes (82,169) or other equipment should be considered (136).

Contact Investigations

The primary goal of contact investigations is to identify secondary cases of TB disease and LTBI among contacts so that therapy can be initiated as needed (263–265). Contact investigations should be collaboratively conducted by both infection-control personnel and local TB-control program personnel.

Initiating a Contact Investigation

A contact investigation should be initiated when 1) a person with TB disease has been examined at a health-care setting, and TB disease was not diagnosed and reported quickly, resulting in failure to apply recommended TB infection controls; 2) environmental controls or other infection-control measures have malfunctioned while a person with TB disease was in the setting; or 3) an HCW develops TB disease and exposes other persons in the setting.

As soon as TB disease is diagnosed or a problem is recognized, standard public health practice should be implemented to prioritize the identification of other patients, HCWs, and visitors who might have been exposed to the index case before TB infection-control measures were correctly applied (52). Visitors of these patients might also be contacts or the source case.

The following activities should be implemented in collaboration with or by the local or state health department (34,266): 1) interview the index case and all persons who might have been exposed; 2) review the medical records of the index case; 3) determine the exposure sites (i.e., where the index case lived, worked, visited, or was hospitalized before being placed under airborne precautions); and 4) determine the infectious period of the index case, which is the period during which a person with TB disease is considered contagious and most capable of transmitting M. tuberculosis to others.

For programmatic purposes, for patients with positive AFB sputum smear results, the infectious period can be considered to begin 3 months before the collection date of the first positive AFB sputum smear result or the symptom onset date (whichever is earlier). The end of the infectious period is the date the patient is placed under airborne precautions or the date of collection of the first of consistently negative AFB sputum smear results (whichever is earlier). For patients with negative AFB sputum smear results, the infectious period can begin 1 month before the symptom onset date and end when the patient is placed under airborne precautions.

The exposure period, the time during which a person shared the same air space with a person with TB disease for each contact, should be determined as well as whether transmission occurred from the index patient to persons with whom the index patient had intense contact. In addition, the following should be determined: 1) intensity of the exposure based on proximity, 2) overlap with the infectious period of the index case, 3) duration of exposure, 4) presence or absence of infection-control measures, 5) infectiousness of the index case, 6) performance of procedures that could increase the risk for transmission during contact (e.g., sputum induction, bronchoscopy, and airway suction), and 7) the exposed cohort of contacts for TB screening.

The most intensely exposed HCWs and patients should be screened as soon as possible after exposure to M. tuberculosis has occurred and 8–10 weeks after the end of exposure if the initial TST result is negative. Close contacts should be the highest priority for screening.

For HCWs and patients who are presumed to have been exposed in a setting that screens for infection with M. tuberculosis using the TST, the following activities should be implemented:

  • performing a symptom screen;
  • administering a TST to those who previously had negative TST results;
  • repeating the TST and symptom screen 8–10 weeks after the end of exposure, if the initial TST result is negative;
  • promptly evaluating the HCW for TB disease, including performing a chest radiograph, if the symptom screen or the initial or 8–10-week follow-up TST result is positive; and
  • providing additional medical and diagnostic evaluation for LTBI, including determining the extent of exposure, if TB disease is excluded.

For HCWs and patients who are presumed to have been exposed in a setting that screens for infection with M. tuberculosis using the BAMT, the following activities should be implemented (see Supplement, Surveillance and Detection of M. tuberculosis Infections in Health-Care Settings). If the most intensely exposed persons have test conversions or positive test results for M. tuberculosis infection in the absence of a previous history of a positive test result or TB disease, expand the investigation to evaluate persons with whom the index patient had less contact. If the evaluation of the most intensely exposed contacts yields no evidence of transmission, expanding testing to others is not necessary.

Exposed persons with documented previously positive test results for M. tuberculosis infection do not require either repeat testing for M. tuberculosis infection or a chest radiograph (unless they are immunocompromised or otherwise at high risk for TB disease), but they should receive a symptom screen. If the person has symptoms of TB disease, 1) record the symptoms in the HCW's medical chart or employee health record, 2) perform a chest radiograph, 3) perform a full medical evaluation, and 4) obtain sputum samples for smear and culture, if indicated.

The setting should determine the reason(s) that a TB diagnosis or initiation of airborne precautions was delayed or procedures failed, which led to transmission of M. tuberculosis in the setting. Reasons and corrective actions taken should be recorded, including changes in policies, procedures, and TB training and education practices.

Collaboration with the Local or State Health Department

For assistance with the planning and implementation of TB-control activities in the health-care setting and for names of experts to help with policies, procedures, and program evaluation, settings should coordinate with the local or state TB-control program . By law, the local or state health department must be notified when TB disease is suspected or confirmed in a patient or HCW so that follow up can be arranged and a community contact investigation can be conducted. The local or state health department should be notified as early as possible before the patient is discharged to facilitate followup and continuation of therapy by DOT (31). For inpatient settings, coordinate a discharge plan with the patient (including a patient who is an HCW with TB disease) and the TB-control program of the local or state health department.

Environmental Controls

Environmental controls are the second line of defense in the TB infection-control program, after administrative controls. Environmental controls include technologies for the removal or inactivation of airborne M. tuberculosis. These technologies include local exhaust ventilation, general ventilation, HEPA filtration, and UVGI. These controls help to prevent the spread and reduce the concentration of infectious droplet nuclei in the air. A summary of environmental controls and their use in prevention of transmission of M. tuberculosis is provided in this report (see Supplement, Environmental Controls), including detailed information concerning the application of environmental controls.

Local Exhaust Ventilation

Local exhaust ventilation is a source-control technique used for capturing airborne contaminants (e.g., infectious droplet nuclei or other infectious particles) before they are dispersed into the general environment. In local exhaust ventilation methods, external hoods, enclosing booths, and tents are used. Local exhaust ventilation (e.g., enclosed, ventilated booth) should be used for cough-inducing and aerosol-generating procedures. When local exhaust is not feasible, perform cough-inducing and aerosol-generating procedures in a room that meets the requirements for an AII room.

General Ventilation

General ventilation systems dilute and remove contaminated air and control airflow patterns in a room or setting. An engineer or other professional with expertise in ventilation should be included as part of the staff of the health-care setting or hire a consultant with expertise in ventilation engineering specific to health-care settings. Ventilation systems should be designed to meet all applicable federal, state, and local requirements.

A single-pass ventilation system is the preferred choice in areas in which infectious airborne droplet nuclei might be present (e.g., AII rooms). Use HEPA filtration if recirculation of air is necessary.

AII rooms in health-care settings pre-existing 1994 guidelines should have an airflow of ≥6 ACH. When feasible, the airflow should be increased to ≥12 ACH by 1) adjusting or modifying the ventilation system or 2) using air-cleaning methods (e.g., room-air recirculation units containing HEPA filters or UVGI systems that increase the equivalent ACH). New construction or renovation of health-care settings should be designed so that AII rooms achieve an airflow of ≥12 ACH. Ventilation rates for other areas in health-care settings should meet certain specifications (see Risk Classification Examples). If a variable air volume (VAV) ventilation system is used in an AII room, design the system to maintain the room under negative pressure at all times. The VAV system minimum set point must be adequate to maintain the recommended mechanical and outdoor ACH and a negative pressure ≥0.01 inch of water gauge compared with adjacent areas.

Based on the risk assessment for the setting, the required number of AII rooms, other negative-pressure rooms, and local exhaust devices should be determined. The location of these rooms and devices will depend partially on where recommended ventilation conditions can be achieved. Grouping AII rooms in one area might facilitate the care of patients with TB disease and the installation and maintenance of optimal environmental controls.

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Copyright 1997-2021 Eric Rechlin.
Источник: [https://torrent-igruha.org/3551-portal.html]

Scripts with documentation (by date)

Total Size of .r Filessizedir.r
 documentationv:1.0.0
557 bytes
13 Mar 2003Print the total size of all .r files in the current directory.
author: Anonymous

Documentation: by btiffin on 5-May-2007.

TCP port scanneroneliner-tcp-port-scanner.r
 documentationv:1.0.0
850 bytes
20 Jul 2003This is a simple port scanner. Given a TCP address, it will tell you which of the first 100 ports are accessible. The address can be a host name or number. For example, use "localhost" to scan ports on your own machine. You can scan more ports by increasing the number (from 100), or you can scan ranges by using a FOR loop rather than REPEAT.
author: Anonymous

Documentation: by btiffin on 5-May-2007.

POP Email Port Specpopspec.r
 documentation850 bytes
13 Mar 2003POP port specification used to connect to an email server. All of the mail reading examples use this.
author: [unknown]

Documentation: by btiffin on 5-May-2007.

Trivial Email List Servermailserver.r
 documentationv:1.0.0
1.2 KB
13 Mar 2003As simple as a list server gets.
author: Anonymous

Documentation: by btiffin on 5-May-2007.

TSN: Tranched serial number servertsn.r
 documentationv:0.0.1
7.6 KB
30 Apr 2007Quick, safe way of allocating categorized unique serial numbers
author: Sunanda

Documentation: by sunanda on 30-Apr-2007.

Rename a Fileftprename.r
 documentation411 bytes
13 Mar 2003Rename a file on a server using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Upload a Fileftpup.r
 documentationv:1.0.0
459 bytes
13 Mar 2003Upload a binary file to an FTP server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Upload Several Filesftpupload.r
 documentationv:1.0.0
585 bytes
13 Mar 2003Upload multiple files with FTP using login and password.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Read a Text Fileftpread.r
 documentation412 bytes
13 Mar 2003Read a text file from an FTP server and print it.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Make a directoryftpmakedir.r
 documentation414 bytes
13 Mar 2003Make a file directory on an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Get File Size and Dateftpinfo.r
 documentation498 bytes
13 Mar 2003Get size and date information about an FTP file.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Upload all HTML Filesftphtml.r
 documentationv:1.0.0
642 bytes
13 Mar 2003Upload a group of files to an FTP server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Download a Binary Fileftpdownbin.r
 documentation470 bytes
13 Mar 2003Download a binary file from an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Interactive FTP Downloaderftpdownload.r
 documentation718 bytes
13 Mar 2003Download a group of files from an FTP server, prompting for each file along the way.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Download List of Filesftpdown.r
 documentation536 bytes
13 Mar 2003Download a list of binary files using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Run Script from FTPftpdo.r
 documentation390 bytes
13 Mar 2003Do a REBOL script via FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Read File Directoriesftpdir.r
 documentation500 bytes
13 Mar 2003Read and print directories from an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Check for Directoryftpdircheck.r
 documentation455 bytes
13 Mar 2003Check if a filename belongs to a directory using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Delete a File or Directoryftpdel.r
 documentation470 bytes
13 Mar 2003Delete a file or directory from a server using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Check for a File or Directoryftpcheck.r
 documentation574 bytes
13 Mar 2003Check for the existence of an FTP file or directory.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Append to a Text Fileftpappend.r
 documentationv:1.0.0
471 bytes
13 Mar 2003Append to a text file using FTP.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Transfer REBOL Files to Serverftpallto.r
 documentationv:1.0.0
625 bytes
13 Mar 2003FTP all .r files in the current directory to a server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Count References on Web Pagescountweb.r
 documentationv:1.0.0
743 bytes
13 Mar 2003Count the number of times a string appears on each of a given set of web pages.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Sends Email via CGI Formcgiemailer.r
 documentationv:1.0.0
855 bytes
13 Mar 2003Uses a Web form to send an email message.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

CGI Emailer Form (HTML Part)cgiemailhtml.r
 documentation1.7 KB
13 Mar 2003HTML form to go with CGI Emailer example (cgiemailer.r).
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

Easy CGI Form Examplecgiform.r
 documentationv:1.0.0
1.1 KB
13 Mar 2003Handles a CGI form and returns its values as a web page. (The associated cgiform.html file contains the form).
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Easy CGI Form (HTML Part)cgiformhtml.r
 documentationv:1.0.0
1.4 KB
13 Mar 2003HTML form to go with Easy CGI example (cgiform.r).
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

CGI Form with Defaultscgiformobj.r
 discussion
 documentation1.3 KB
13 Mar 2003Handles a CGI form, providing default values for missing fields in the form. Returns a web page. (The associated cgiform.html file contains the form).
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

CGI Comment Articlewebcomment.r
 documentation2.9 KB
13 Mar 2003Run this to create the file used for the cgicomment.r script.
author: Carl Sassenrath

Documentation: by btiffin on 28-Apr-2007.

CGI Web Page Comment Postercgicomment.r
 documentation3.0 KB
13 Mar 2003Allows viewers to add comments to a web page. (needs webcomment.r to create example forms file).
author: Carl Sassenrath

Documentation: by btiffin on 28-Apr-2007.

CGI Form Emailercgimail.r
 documentation736 bytes
13 Mar 2003Emails the contents input into a web CGI form.
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

CGI Form Dumpercgidump.r
 documentation785 bytes
13 Mar 2003Display the contents of a submitted form as a web page. Useful for debugging CGI forms.
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

Display Black Textblack-text.r
 documentationv:1.0.0
512 bytes
13 Mar 2003Display black text on a white background.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Images Buttonsbutton-image.r
 documentationv:1.0.0
762 bytes
13 Mar 2003Example of how to make buttons made from images. Clicking on a button updates text in the window.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

A Button with Shortcut Keybutton-key.r
 documentationv:1.0.0
479 bytes
13 Mar 2003Shows how to easily add a shortcut key to a button.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

SKIMP: Simple keyword index management programskimp.r
 documentationv:0.0.2
40.3 KB
3 May 2007Simple, fast way of indexing the text content of many documents
author: Sunanda

Documentation: by sunanda on 28-Apr-2007.

periodic tableperiodictable.r
 documentationv:0.9.4
11.9 KB
15 Aug 2007Display a periodic table of the elements as REBOL buttons
author: Brian Tiffin

Documentation: by btiffin on 25-Apr-2007.

Alien Dialectalien.r
 documentationv:1.0.0
1.9 KB
13 Mar 2003It came from outer space
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Alien Dialect Explanationalienexp.r
 documentationv:1.0.0
1.4 KB
13 Mar 2003It came from outer space explained.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

REBOL Alebeer.r
 documentationv:1.0.0
1.3 KB
13 Nov 2003A rich, malty, copper brew.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

99 Bottles of Beer Songbeersong.r
 documentationv:1.0.0
813 bytes
13 Mar 2003The correct song. A bit more advanced.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Binary Data in REBOL Scriptsbin-data.r
 documentationv:1.0.0
8.8 KB
13 Mar 2003Example of how to decode binary data in REBOL scripts This example includes a base-64 encoded image. (See bin-save.r for an example of how to create this file.)
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Encoding Binary Data in REBOL Scriptsbin-save.r
 documentationv:1.0.0
603 bytes
13 Mar 2003Example of how to save base-64 encoded binary data in REBOL scripts. (See bin-data.r as an example of how to decode the data.)
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Email Blasterblast.r
 documentationv:1.0.0
1.8 KB
13 Mar 2003Send an email to everyone on a spreadsheet of email addresses. Personalize the greeting for each. Keep a log of who was been sent the message.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

make-word-listmake-word-list.r
 documentationv:1.0.0
16.5 KB
2 Apr 2007Makes a list of words from a string
author: peter

Documentation: by peterwood on 4-Apr-2007.

Run sequence encoded integer data setsrse-ids.r
 documentationv:0.0.1
7.0 KB
21 Feb 2007Provide an API for compacting/compressing sets of integers
author: christian

Documentation: by sunanda on 21-Feb-2007.

Calculate working days between two dateswork-days.r
 documentationv:0.0.1
1.7 KB
18 Feb 2007Given two dates, and a list of holidays that occur between them, returns the number of work days between those two days. With the /non refinement, will return the number of non-working days between the two dates.
author: Sunanda

Documentation: by sunanda on 18-Feb-2007.

Anonymous CGI session servicesacgiss.r
 documentationv:0.0.1
8.1 KB
18 Dec 2006Provide basic cookie support for CGI scripts
author: Sunanda

Documentation: by sunanda on 18-Dec-2006.

File globbing module and dialectfile-list.r
 discussion
 documentationv:0.0.2
30.2 KB
19 Oct 2006Given a file spec, and optional criteria for date, size, and attributes, the FILE-LIST function returns a block of files that match the spec and criteria. It is also a test-bed for how to integrate dialects with one-another. There are sub-dialects for date, size, and attribute tests, and FILE-LIST encapsulates those, along [...]
author: Gregg Irwin

Documentation: by greggirwin on 16-Oct-2006.

VB Like Operator Module/pattern-matcherlike.r
 documentationv:0.0.3
6.7 KB
15 Oct 2006The LIKE? function is a first crack at something like VB's Like operator. i.e. a *very* simple RegEx engine as you would use in shells for file globbing. The real purpose was to help me get acquainted with parse.
author: Gregg Irwin

Documentation: by greggirwin on 16-Oct-2006.

Qtask Markup Language - parser and other common codeqml-base.r
 documentationv:2.46.1
97.1 KB
28 May 2007This program implements the base for QML (Qtask Markup Language) converters (for example it's the base for a QML to XHTML converter used in Qtask), by implementing the parsing of a QML text string into a QML document tree.
author: Gabriele Santilli

Documentation: by gabriele on 28-Aug-2006.

Qtask Markup Language - XHTML emitterxhtml-emitter.r
 documentationv:2.19.1
35.1 KB
28 May 2007This program implements a QML to XHTML converter. The input is a QML document tree (from the QML parser), and the output is XHTML text.
author: Gabriele Santilli

Documentation: by gabriele on 28-Aug-2006.

Qtask Markup Language Editorqml-ed.r
 documentation496 bytes
23 Aug 2006Edit QML files, create HTML from QML
author: Gabriele Santilli

Documentation: by gabriele on 23-Aug-2006.

ImageMagick Supportimagemagick-helper.r
 documentation8.8 KB
23 Aug 2006Support minimal needs for image processing using ImageMagick MagickWand and MagickCore DLLs Note: DLL's calls tend to change so this is specifically for version 6.2.9 Note: Original uses only MagickCore DLL. This version required MagickWand DLL because they moved the calls to a different DLL
author: Edgar Tolentino

Documentation: by sunanda on 23-Aug-2006.

Sintezar PM-101 - Phase Manipulation Digital Synthesizerpm-101.r
 documentationv:0.4.0
81.3 KB
23 Jun 2006synthetiser
author: Boleslav Brezovsky

Documentation: by rebolek on 23-Jun-2006.

Textile Parsertextile.r
 documentationv:0.2.0
16.2 KB
16 Jun 2006Transforms Textile-formatted text into HTML
author: Brian Wisti

Documentation: by brianwisti on 16-Jun-2006.

Skype Wrapperskype.r
 discussion
 documentation2.2 KB
23 May 2006make a cheap phone call!
author: Graham Chiu

Documentation: by gchiu on 23-May-2006.

Safe CGI data retrieversafe-cgi-data-read.r
 documentationv:0.0.2
3.4 KB
22 Jun 2011Safely retrieves CGI GET or POST data into a REBOL object.
author: Sunanda

Documentation: by sunanda on 21-May-2006.

(R)EBOL (Un)itrun.r
 discussion
 documentation19.1 KB
31 May 2008RUn is a TestCase Framework wich allows the use of TestCases as defined by the eXtreme Programming development methodology and the test-driven development
author: Christophe 'REBOLtof' Coussement

Documentation: by reboltof on 15-May-2006.

RebelXMLrebelxml.r
 discussion
 documentation8.0 KB
27 Apr 2006RebelXML provides a set of functions which allows to easily create/modify/delete XML data
author: Christophe 'REBOLtof' Coussement

Documentation: by reboltof on 28-Apr-2006.

Library Interface Dialectlib-dialect.r
 documentation2.4 KB
14 Apr 2006Allow for a more concise way to define library routine interfaces.
author: Gregg Irwin

Documentation: by greggirwin on 14-Apr-2006.

xCopyxcopy.r
 documentationv:1.0
3.2 KB
11 Apr 2006REBOL implementation of the well-known xcopy tool. xcopy allows you to copy in one move files, directories, subdirectories and contained files to a given location.
author: Christophe 'REBOLtof' Coussement

Documentation: by reboltof on 11-Apr-2006.

Library data serviceslds-local.r
 documentationv:0.0.4
655 bytes
13 Aug 2004Provides the client end of the REBOL.org Library Data Services interface
author: Sunanda

Documentation: by sunanda on 2-Mar-2006.

Similarity Metricssimetrics.r
 discussion
 documentationv:0.5.0
21.2 KB
19 Feb 2006Toolkit of string distance metrics.
author: Francois Vanzeveren (fvz)

Documentation: by fvzv on 19-Feb-2006.

Prime number checkerprime.r
 documentationv:0.0.2
3.0 KB
13 Mar 2003Address the question, could this integer be a prime number? results of false are not prime, results of true are very probably prime and with the /strong refinement, ( I still have to verify this ) true ( should ) guarantee prime. if the argument is outside the domain of the function, none is returned
author: Tom Conlin

Documentation: by tomc on 18-Oct-2005.

Stack, queue and deque functionssqd.r
 documentationv:0.0.1
4.1 KB
5 Oct 2005Implement stack, queue and deque data structures
author: Sunanda

Documentation: by sunanda on 5-Oct-2005.

Prolog Like Inference Engineprolog.r
 discussion
 documentationv:1.7
43.1 KB
3 Jan 2011This is an inference engine wich process prolog like clause The engine can process prolog like clauses of the form : man [jean] woman [mary] human [X] [man [X]] human [X] [woman [X]] CUT (!) and FAIL are implemanted (it's the only hardcoded predicates in the engine) The engine execute Rebol code [...]
author: Marco

Documentation: by coccinelle on 15-Aug-2005.

REBOL Diff and Patch functionsreboldiff.r
 documentationv:1.1.1
11.5 KB
29 Jul 2005Implements diff and patch in REBOL. Allows you to see differences between text files.
author: Gabriele Santilli

Documentation: by gabriele on 29-Jul-2005.

DO-POP Schemedo-pop-scheme.r
 documentation7.3 KB
10 Jul 2005A scheme to allow flexible POP3 operations.
author: Brett Handley

Documentation: by brett on 24-Jul-2005.

Nim enginenim-engine.r
 documentationv:0.0.0
12.7 KB
19 Jul 2005Calculate the best move in a game of NIM
author: Sunanda

Documentation: by sunanda on 19-Jul-2005.

Event profile timerprofile-timer.r
 documentationv:0.0.0
2.2 KB
13 Oct 2004Helps you time events when tuning code
author: Sunanda

Documentation: by sunanda on 13-Jul-2005.

JSON to Rebol converterjson.r
 discussion
 documentationv:0.0.9
14.2 KB
6 Sep 2013Convert a JSON string to Rebol data, and vice versa.
author: douglas crockford

Documentation: by sunanda on 7-Jul-2005.

Logging Framework For Rebollog4reb.r
 documentationv:2.0.6
10.8 KB
19 Feb 2006Logging within the context of program development constitutes inserting statements into the program that provide some kind of output information that is useful to the developer. Examples of logging are trace statements, dumping of structures and the familiar 'prin or 'print debug statements. log4reb offers a hierarchical way to insert logging statements within a [...]
author: Francois Vanzeveren

Documentation: by fvzv on 3-Jul-2005.

Patch for REBOL FTP protocol 226 response handling.patch-ftp-226-handling.r
 documentation5.2 KB
2 Jul 2005To fix FTP protocol 226 response handling.
author: Brett Handley

Documentation: by brett on 3-Jul-2005.

Simple Test Suitetest-simple.r
 documentationv:0.3.0
6.3 KB
15 Jun 2006Add support for simple test mechanisms to REBOL, similar to Perl's Test::Simple. The basic idea? Make testing simple so everybody can make tests.
author: Brian Wisti

Documentation: by brianwisti on 8-Mar-2005.

REBOL Bloggerblog.r
 documentationv:1.3.2
18.3 KB
10 Jan 2005The blog system written and used by Carl Sassenrath, REBOL's creator. This script will let you post and update blogs on your website using just a web browser. Generates summary and index pages, blog searches, etc. Extensible with Makedoc2 for more formatting options.
author: Carl Sassenrath

Documentation: by carl on 11-Jan-2005.

Base conversion functionsbase-convert.r
 documentationv:0.0.2
8.0 KB
2 Sep 2005Functions to convert an decimal whole number to and from any arbitrary base
author: Sunanda

Documentation: by sunanda on 12-Dec-2004.

style-tooltip.rstyle-tooltip.r
 documentationv:1.0
2.9 KB
29 Nov 2004Use in the simplest way the tooltip. This is a first intent it's a little bit deprecated and we have worked on a better way to generate and handle tooltips. I share this with you because I think this code have a good educationnal value and is a good point start if you are interested in tooltips avanced filnal version please visit http://rebol.agora-dev.org/ . Sample script [...]
author: Shadwolf, Boss, DideC

Documentation: by shadwolf on 29-Nov-2004.

pluginable analog alarm clockaclock-p.r
 documentation3.5 KB
20 Sep 2004aproximate an analog clock and add alarm
author: Tom Conlin

Documentation: by tomc on 20-Sep-2004.

Dynamic Script Localizationlocale.r
 documentationv:1.0.1
12.6 KB
6 Sep 2004Locale.r extends the system/locale objet in order to supply a dynamique localization of applications
author: marco

Documentation: by coccinelle on 6-Sep-2004.

make-doc-promake-doc-pro.r
 documentationv:1.0.8
57.8 KB
7 Feb 2004Parses the make-doc-pro markup language into a datastructure that can be into other document formats (such as HTML) with good titles, table of contents, section headers, indented fixed-spaced examples, bullets and definitons.
author: Robert M. M�nch

Documentation: by robert on 30-Aug-2004.

read-belowread-below.r
 discussion
 documentationv:1.0.0
3.6 KB
13 Aug 2004Reads all files and directories below specified directory
author: Brett Handley

Documentation: by brett on 17-May-2004.

cookie-example.rcookie-example.r
 documentationv:1.0.1
7.5 KB
13 Aug 2004Demonstrates how to set session cookies and use them to retrieve session variables. Much of the code has been cobbled together from much more structured (ie not all in one module) code used by rebol.org itself
author: Sunanda

Documentation: by sunanda on 8-Dec-2003.

Prime factorsoneliner-prime-factors.r
 documentation556 bytes
23 Jun 2008[no purpose header found]
author: Sunanda

Documentation: by sunanda on 28-Nov-2003.

CGI wrapper function for debuggingcgi-debug.r
 discussion
 documentationv:0.0.1
2.6 KB
7 Jan 2005Provides debugging info for scripts running as a CGI under a webserver
author: Sunanda

Documentation: by sunanda on 26-Nov-2003.

Parse ini fileparse-ini.r
 discussion
 documentationv:1.0.2
2.2 KB
15 Apr 2009Parses a Window's ini file. Also a function to find entries in a parsed ini file
author: Sunanda

Documentation: by sunanda on 12-Nov-2003.

REM 0.4.2 - Text Editor - self extracting archiverem-ext42.r
 documentationv:0.4.2
25.9 KB
13 Mar 2003REM is a powerful full screen text editor for Rebol/Core and Rebol/View
author: Cal Dixon

Documentation: by caldixon on 17-Oct-2003.

SiMTPop Simulate SMTP & POPsimtpop.r
 documentation4.5 KB
13 Nov 2003To simulate SMTP and POP services on a single user PC, works with Outlook 98, but is broken for later Versions
author: Ingo Hohmann

Documentation: by iho on 10-Oct-2003.

Monty Hall Challengeoneliner-monty-hall.r
 documentationv:1.0.0
694 bytes
13 Aug 2004Simulates swapping doors after Monty shows a goat. Result is percentage wins after 100 runs. (MHC: a well-known and often debated probability puzzle involving three doors, two goats, and a car).
author: Sunanda (with tweaks from Romano T, Ryan C, Carl R, and Reichart)

Documentation: by sunanda on 22-Sep-2003.

Источник: [https://torrent-igruha.org/3551-portal.html]
OverviewSystem Requirements

Description

Tired of playing stereotype mindless games over and over? Looking for a different type of game that can really challenges and tease your brain. Look no further as your answer lies with Brain Boss. It’s an exciting color and number matching game that will test your brain’s workout skill simply by tapping the correct answer on the screen. Sounds simple! But it will also improve your memory skills. Brain Boss is designed scientifically to push you and your brain to the limits. You have to tap the right number with the right color at the right time. There is a time window for each given number, and wrong taps will decrease your time for each round up to five times, after which the game ends and you get your results. So you want to challenge your concentration ability? Aren’t YOU? It’s a serial of taps, if you can. If you are up to the challenge, start playing now for FREE and see how your brain stacks up against others! ***Features*** - Fast paced. Challenging gameplay - Minimalistic yet aesthetically pleasant UI - Calculates your brain’s co-ordination capabilities and compares it against others! Having any problems or suggestion? We would really love to hear your opinion! You can reach us at contact@riseuplabs.com Or *Follow us on Twitter : @RiseUpLabs *Like us on Facebook : https://www.facebook.com/riseuplabs *Follow us on Google+ : https://plus.google.com/+riseuplabs *Watch us on YouTube : http://www.youtube.com/RiseUpLabs *Visit our Website : http://www.riseuplabs.com

Features

  • Fast paced. Challenging gameplay
  • Minimalistic yet aesthetically pleasant UI
  • Calculates your brain’s co-ordination capabilities and compares it against others!

System Requirements

OSWindows 8 Mobile
Architecturex86, x64, ARM, ARM64
TouchIntegrated Touch
OSWindows 8 Mobile
Architecturex86, x64, ARM, ARM64
TouchNot specified
Источник: [https://torrent-igruha.org/3551-portal.html]

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OverviewSystem Requirements

Description

Tired of playing stereotype mindless games over and over? Looking for a different type of game that can really 99 Bottles 1.0 crack serial keygen and tease your brain. Look no further as your answer lies with Brain Boss. It’s an exciting color and number matching game that will test your brain’s workout skill simply by tapping the correct answer on the screen. Sounds simple! But it will also improve your memory skills. Brain Boss is designed scientifically to push you and your brain to the limits. You have to tap the right number with the right color at the right time. There is a time window for each given number, and wrong taps will decrease your time for each round up to five times, after which the game ends and you get your results. So you want to challenge your concentration ability? Aren’t YOU? It’s a serial of taps, if you can. If you are up to the challenge, start playing now for FREE and see how your brain stacks up against others! ***Features*** - 99 Bottles 1.0 crack serial keygen paced. Challenging gameplay - Minimalistic yet aesthetically pleasant UI - Calculates your brain’s co-ordination capabilities and compares it against others! Having any problems or suggestion? We would really love to hear your opinion! You can reach us at contact@riseuplabs.com Or *Follow us on Twitter : @RiseUpLabs *Like us on Facebook : https://www.facebook.com/riseuplabs *Follow us on Google+ : https://plus.google.com/+riseuplabs *Watch us on YouTube : http://www.youtube.com/RiseUpLabs *Visit our Website : http://www.riseuplabs.com

Features

  • Fast paced. Challenging gameplay
  • Minimalistic yet aesthetically pleasant UI
  • Calculates your brain’s co-ordination capabilities and compares it against others!

System Requirements

OSWindows 8 Mobile
Architecturex86, x64, ARM, ARM64
TouchIntegrated Touch
OSWindows 8 Mobile
Architecturex86, x64, ARM, ARM64
TouchNot specified
Источник: [https://torrent-igruha.org/3551-portal.html]

Fragmentation of plastic objects in a laboratory seawater microcosm

Abstract

We studied the fragmentation of conventional thermoplastic and compostable plastic items in a laboratory seawater microcosm. In the microcosm, polyurethane foams, cellulose acetate cigarette filters, and compostable polyester and polylactic acid items readily sank, whereas polyethylene air pouches, latex balloons, polystyrene foams and polypropylene cups remained afloat. Microbial biofilms dominated by Cyanobacteria, Proteobacteria, Planctomycetes and Bacteriodetes grew on the plastics, and caused some of the polyethylene items Adobe afterefects 6.0 crack serial keygen sink to the bottom. Electrical resistances (ER) of plastic items decreased as function of time, an indication that seawater had penetrated into microscopic crevices in the plastic that had developed over time. Rate constants for ER decrease in polyethylene items in the microcosm were similar to tensile elongation decrease of polyethylene sheets floating in sea, measured previously by others. Weight loss of plastic items was ≤ 1% per year for polyethylene, polystyrene and polypropylene, 3–5% for latex, polyethylene terephthalate and polyurethane, 15% for cellulose acetate, and 7–27% for polyester and polylactic acid compostable bags. The formation of microplastics observed in the microcosm was responsible for at least part of the weight loss. This study emphasizes the need to obtain experimental data on plastic litter degradation under conditions that are realistic for marine environments.

Introduction

Millions of tonnes of plastic waste are estimated to enter the oceans annually1,2. The issue of widespread plastic waste in the environment is exacerbated by the durability and persistence of these materials in the environment3,4,5,6,7,8,9,10,11,12,13,14,15,16,17. In the marine environment plastic breaks up into smaller particles18,19,20. An estimated 13% to 32% of the total weight of buoyant plastics in the oceans consists of microplastic particles of 0.3–5 mm in size14,21,22. It is currently unknown how and at which rates fragmentation of plastic proceeds. We also do not know to which degree biodegradation contributes to the mineralization of plastic in seawater23,24,25,26,27,28,29,30,31,32. This lack of data limits our capability to assess and predict the fate and residence times of plastic litter in marine ecosystems. The present study sought to shed some light on plastic litter fate in a marine microcosm to learn more about the processes and rates that could be observed.

Fragmentation of plastics is thought to be initiated by polymer chain backbone weathering through exposure to sunlight (UV), oxidants, hydrolysis and physical shearing, for example through currents, waves, or friction with sand4,33,34,35,36,37,38,39,40. The oxidation and shortening of polymer chains and leaching of plasticizers makes plastic materials brittle and stimulates the formation of surface cracks and fragmentation18,19. As a result micro- and nanometer sized plastic particles may be released from the surface of larger fragments19. In time this can result in the generation of numerous micro- and nanoplastic particles from a single plastic object18. In theory, one bag composed of two plastic sheets 50 cm × 40 cm × 50 µm thick could generate 20 particles with a volume of 1 mm3, 20 million particles with a volume of 1 µm3 or 20 trillion particles with a volume of 1 nm3.

The size of the plastic particles is important because it affects their potential hazard to individual organisms, communities, and ecosystems. Larger plastic litter items may be eaten by or cause entanglement of marine fish, 99 Bottles 1.0 crack serial keygen, birds and mammals, while the micro- and nanoplastic particles are more prone to being ingested not only by large, but also by smaller invertebrates such as mussels and zooplankton with the potential for accumulation in food chains19,41.

Fragmentation also affects plastic litter transport through marine systems because smaller particles are transported differently horizontally and vertically than larger 99 Bottles 1.0 crack serial keygen. Smaller particles have a relatively large exposed surface area 99 Bottles 1.0 crack serial keygen to their volume. This may result in increased degradation rates, adsorption sites IOBIT Driver Booster 6 pro crack serial keygen unit mass and reduced buoyancy (upon biofouling), resulting in transfer of microplastic particles from the sea surface to the water column or sediment9,11,14,18,48. The larger specific surface area generated through fragmentation increases contact with water with faster leaching or sorption rates for chemicals and additional area for biofouling49.

In 2018, about 359 million tonnes plastic were produced globally, of which 62 million tonnes in Europe. About 80% consisted of thermoplastics with polymer backbones of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane (PU), polystyrene (PS) or polyethylene terephthalate (PET)50. The material composition, e.g. chain backbone, crosslinking and additives, affects to a high degree the repertoire of mechanisms and rates of abiotic and biological degradation that can occur. Polymers with a carbon–carbon backbone, high molecular weight, and few functional groups, such as PE, PP, PS and PVC, are very resistant to degradation9. Ultraviolet (UV) light from the sun produces breaks in for example PE, PP, PS and PVC polymer chains. But in marine ecosystems such plastic particles are readily transferred downwards and often become buried in the sediment. Floating plastic particles become rapidly covered by biofilms, which protect them from UV radiation51,52 and weigh them down, causing them to sink. The timescale of the mineralization process of most plastic materials with a carbon–carbon backbone in the marine environment is usually estimated at decades or longer9,24,33,38.

Plastic materials with heteroatoms in the main polymer chain are susceptible to hydrolysis9. In the marine environment, cleavage of the ester bonds in PET and PU and amide bonds in nylon can occur through abiotic hydrolysis, photolysis and oxidation. In addition, biodegradation of PET and PU may be significant, since microorganisms that are capable of this process can readily be isolated from the environment, including marine systems26,27,30,53,54.

Microorganisms in biofilms are sometimes able to catalyze the partial or complete mineralization of plastic to energy, biomass and inorganic molecules such as carbon dioxide, water, and/or methane, hydrogen and ammonia21,22,23,24,25,26,27,28,29,30,53,54,55,56,57,58,59,60,61. The biodegradability of plastic materials is usually determined under conditions optimized for high metabolic rate (temperature, nutrients, pH) such as in sewage sludge, landfill, soil or compost, but not under conditions which prevail in marine environments57. Therefore, such tests are unreliable indicators of the fate of plastic items in the sea.

One way proposed to reduce the persistence of plastic objects in the environment is to use polymers that mineralize more readily through biodegradation58. Natural resources such as cellulose, starch, polylactic acid (PLA), and polyhydroxyalkanoates (PHA) are often used for the production of biodegradable plastics58,59,60. Internationally recognized standards, EN 13,432 (European), ASTM 6400 (USA) or ISO 17088 (International) are used to define and label the biodegradability of plastic materials59,60. According to these standards, a plastic product can be “compostable-labelled” if at least 90% (weight) disintegrates into particles that pass through a 2 × 2 mm mesh within 3 months and mineralize within 6 months in an industrial composting environment. According to these laboratory tests, plastic items are mixed with biowaste and typically exposed at temperatures in the range between 40 and 60 °C. Obviously, these tests do not represent the conditions prevailing in the marine environment, which points out the need to assess the fragmentation and biodegradation of compostable-labelled plastic materials in seawater.

Fragmentation rates of plastic litter are likely to vary widely according to environmental conditions and the plastic material grade in question. The rates will also not be constant in time, as the degradation results from a variety of independent and interdependent processes (e.g.biodegradation, hydrolysis, photooxidation, erosion, cracking, etc.) that do not proceed at the same rates and do not stay constant over time. Such rates have only been roughly estimated in outdoor exposure experiments in seawater, with rare attempts to determine loss of tensile strength or surface area4,19,33,38. The rates at which we can expect plastics to completely mineralize in the sea are expected to be very low and challenging to empirically measure or quantify61.

Quantifying weathering, fragmentation and mineralization rates of different types of plastic objects in a marine environment with existing methods is not straightforward57. We therefore designed a fit-for-purpose laboratory microcosm experiment to investigate biofouling and fragmentation of a variety of plastic objects within a relatively short time span. We determined growth and species composition of biofilms on the plastic items in the microcosm to observe if differences developed depending on the type of material. We hypothesized that weathering and release of small fragments result in the development of pores and crevices in the surface of plastic objects in the microcosm, and when these pores are filled with seawater this can be measured as a decrease of electrical resistance of the plastic objects62,63. Therefore, we tested the effectiveness of electrical resistance of plastic objects as a simple and fast indicator of plastics weathering and fragmentation. We analyzed weight loss to determine fragmentation caused by microplastics generation and/or biodegradation of each plastic type, to test our prediction that plastic products carrying ‘compostable’ labels would fragment faster than conventional thermoplastics in the microcosm over the course of a one-year experiment.

Results

Once the silicon tubes, PET bottles and fleece, PS coffee cups and the PLA materials were placed in the microcosm, they immediately sank to the bottom because of a higher density than seawater. The PU foams, cigarette filters, paper coffee cups and compostable plastic bags with registration numbers 7P0059 and 7P0069 became waterlogged and sank within 4 days. The other plastics, including the HDPE and the LDPE air pouches, latex balloons, PS foams and PP cups remained afloat on the water surface in the microcosm during the entire experiment (Fig. 1). After one year, only one of the six HDPE and two of the three LDPE air pouches had sunk to the bottom of the microcosm.

Pictures of (A) the marine microcosm and (B) added plastic objects with different polymer backbones.

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After 378–383 days in the microcosm the volume fraction (Φ) of water in different plastic items (estimated by triplicate measurements of the capacitance) were 0.79 ± 0.47 (LDPE air pouch), 1.34 ± 0.32 (HDPE air pouch), 1.38 ± 0.39 (PP cup), 1.45 (PET bottle), 2.01 ± 0.11 (PS coffee cup), and 2.18 ± 0.25 (latex balloon). This indicated the uptake of seawater into the plastic objects during incubation in the microcosm.

Electrical resistance (ER) measurements

The ER of different plastic materials in seawater was measured in triplicate within 8 days after incubation, and subsequently at 50 to 150-day intervals during one-year incubation in the microcosm (Table 1). Initially, ER values of the compostable-labelled plastic bags were more than two log-factors lower than those of the non-compostable plastic items. The highest ER values were found for the PET bottles. For all plastic items the ER values measured at 100 Hz, 120 Hz or 1,000 Hz decreased during incubation in the microcosm (Fig. 2), 99 Bottles 1.0 crack serial keygen. The rate constant at which the ER-values measured at 100 Hz and 120 Hz decreased ranged from 0.0045 day−1 to 0.0165 day−1, depending on the plastic material (Table 1).

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Electrical resistances of latex balloons (upper panel), and compostable trash bags 99 Bottles 1.0 crack serial keygen (lower panel), measured at different times during incubation in the microcosm. Electrical resistances were recorded at 100 Hz (□), 110 Hz (∆), or 1,000 Hz (x)0 Hz (o), respectively.

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After 378–390 days in the microcosm, the ER values of PP and PS cups and an LDPE air pouch were measured before and immediately after removing biofilms and washing in demineralized water. We did this in order to remove seawater from the plastics. After this cleaning and washing, the ER values had increased to the range of the initial values when we started the microcosm. This indicated that low ER-values were primarily due to the uptake of seawater by the plastic items.

Fragmentation and weight loss of the plastics

The first effects of microcosm incubation on the plastic material could be observed within the first week of the experiment. First, we observed a change in colour of the compostable trash bags with registration number 7P0069 from translucent light green into opaque white after four days of incubation. In addition, cigarette filters started to lose their paper covers.

Within two months many holes of 1 mm to 10 mm diameter appeared in the 7P0069 compostable trash bags (Fig. 3). Small particles of < 1 mm broke off of the rims of the larger holes. The compostable postal bags with Multimedia Tools Archives - MASTERkreatif number 7P0059 kept their integrity longer, but some holes of about 1 mm were observed after six months in the microcosm (Fig. 3).

Pictures of fragmentation of compostable trash bag 7P0069 after 0, 57 and 183 days from left to right, respectively (upper panels), compostable postal bag 7P0059 after 294 days (lower left panel) and latex balloon after 383 days (lower right panel) in the microcosm.

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After 378 days, loss of small crumbles (< 1 mm) was visible around the neck of the latex balloons (Fig. 3). The compostable PLA food bags and the paper coffee cups however did not show any signs of fragmentation. These materials did however become fragile and easily disintegrated upon touch. Fragmentation of the PLA bags did not result in formation of small crumbs, but rather elongated snippets. The other plastic materials showed no visible fragmentation within one year in the microcosm.

After 378–427 days the plastics were taken from the microcosm and the dry weight of 3 to 12 replicates was determined after removing the biofilms from the surfaces (Fig. 4). The LDPE and HDPE air pouches, the PS coffee cup, the PP cup and the PLA food tray had lost less than one percent of their weight (fragmentation rates < 1% per year). Based on weight loss, the silicon tubes and the PS packaging foam had fragmentation rates of about 1% per year. Fragmentation rates of the PET materials, PUR foam and the latex balloons were between 3 and 5% per year. Higher fragmentation rates, ranging from 7 to 27% per year were found for the compostable bags and the cigarette filters. The fragmentation rate of the paper coffee cups, as natural cellulose polymer reference, was about 8% per year.

Fragmentation rates (% weight loss per year) of objects with different polymer backbones in the marine laboratory microcosm. Red bars indicate polymers with a backbone with single “C–C” carbon bonds, orange 99 Bottles 1.0 crack serial keygen backbone with double “C = C” bonds, purple a siloxane backbone, blue a polyester backbone, and green indicates compostable polymers.

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Microplastics

Qualitative observations with light microscopy revealed that the water samples taken from the bottom of the microcosm tank contained the highest number and variety of particles, both plastic and organic matter. Samples of water taken at 25 cm depth contained relatively low amounts of particles, mainly fibres (Fig. 5). Small plastic fragments were detected mainly in the water from the surface and on the bottom of the microcosm, indicating materials present in the plastic mixture were generally not neutrally buoyant. Numerous fibers and non-plastic debris were observed in the water samples taken from the surface and bottom of the microcosm (Fig. 5), 99 Bottles 1.0 crack serial keygen. In the reference synthetic seawater, only one particle was detected in a 522 mL sample volume, indicating a very low background level of the incubation seawater compared to the microcosm test.

Images of microplastics and -debris from the microcosm. a Microdebris from the surface water, blue fiber (left), red Kaspersky Internet Security With Activation Code (2022) Free Download (middle), blue foil (right). b Red (left) and blue (right) fibers detected at 25 cm depth. c Microdebris from the bottom at 50 cm depth, blue foil (upper left), white foil (upper middle), brown sphere (upper right), unknown white piece (lower left), and unknown particles (lower right).

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Biofouling and microbial populations on plastics

Heavy biofouling occurred within several months, indicating the growth of algae, bacteria and other microorganisms on the surfaces of the plastic materials (Fig. 6). After 378–427 days in the microcosm, the wet and dry weights of the biofilms growing 99 Bottles 1.0 crack serial keygen 2 to 6 replicates of plastic items were determined (Table 2). Determination of the weight of biofilms growing on the cigarette filters, paper coffee cups and PLA food bags was not possible because these materials were too fragile for biofilm collection. The wet weight measurements indicated the presence of thick slimy biofilm layers on all the components added to the microcosm. The dry weight of the biofilms removed from the plastics ranged from 0.068 to 0.459 mg per cm2 of plastic surface exposed to the seawater, which corresponded to biofilm growth rates of 0.063 to 0.441 mg per cm2 per year.

Biofouling of polypropylene cup, after (from left to right) 0, 57, 183 and 390 days in the microcosm, respectively.

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To study the microorganisms in these biofilms, we performed a DNA metabarcoding approach on six samples, in which we focused on the bacterial community (V3-V4 16S rRNA gene sequencing). First, we checked the bacterial community diversity (Shannon–Wiener 99 Bottles 1.0 crack serial keygen and the richness on the basis of the number of observed operational taxonomic units (OTUs). The lowest number of bacterial OTUs (189) was counted on the PE sample, which also corresponded to the lowest community diversity (2.02). The number of observed OTUs ranged between 307 and 452 for the other samples (Table 3). For the diversity, a mean value of 3.63 ± 0.42 was measured (Table 3). Second, we looked to the community composition on the plastics. Cyanobacteria dominated in all samples, followed by the phyla Proteobacteria, Planctomycetes and in lesser amount the Bacteriodetes (Fig. 7A). Analysis on genus level showed that one specific genus, Leptolyngbya, which was assigned to seven OTUs, dominated the biofilms on all plastic samples and the steel (Fig. 7B). The phyla and genus plots indicated differences in composition between samples, which are also illustrated by a principal coordinates analysis (PCoA) plot (Fig. 8). PE, PP and PS bacterial communities phylogenetically differed most from each other. In comparison, the microbial community of the rope and the steel wall showed the most resemblance.

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Relative abundance of 16S rRNA genes of biofilm samples from the microcosm (A) phylum level (B) genus level. Figures show only those phyla/genera, which represent at least 1% of the total community in at least one sample.

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PCoA plot 99 Bottles 1.0 crack serial keygen the phyla and genus, indicating differences in bacterial population composition between biofilm samples from different objects.

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Discussion

Fragmentation of plastic items can be estimated with a variety of analytical techniques, based on morphological and rheological changes, or on gravimetric, scanning electron microscopy (SEM), spectroscopic or chromatographic analyses56. Many of these methods destroy the plastic samples during analysis and rely on the availability of expensive laboratory equipment. We therefore investigated if electrical resistance (ER) measurements can be applied as a cheap, easy to use, non-destructive alternative. A similar technique, electrochemical impedance spectrometry (EIS), is used to detect pits in paints and coatings, that are too small to be seen microscopically63,64. We used a simple setup to measure the ER of plastic objects submerged in seawater, 99 Bottles 1.0 crack serial keygen. The decrease of ER-values observed at low AC-frequencies (100 Hz–1,000 Hz) as a function of time is in line with EIS analyses of coatings. Capacitance measurements, 99 Bottles 1.0 crack serial keygen, and the fact that after washing in demineralized water the ER restored to initial high values, confirm that the ER measurements indicate penetration of water and ions into the plastics. One might hypothesize that this is correlated to the release of plastic particles from the macroplastic objects in the microcosm. The decrease of tensile elongation at break is a common parameter used to asses polymer degradation rates19,33,65. Interestingly, the degradation rate constant of 0.005 day−1, obtained by ER measurements in our laboratory microcosm at 24 °C for LDPE degradation, is in the range of those obtained by Andrady (1993) for different types of control LDPE sheets floating in outdoor sea experiments, using tensile elongation measurements. Degradation rate constants of LDPE sheets floating in sea at Seattle, at mean temperature of 15 °C, were 0.002–0.004 day−1, and at sea near Miami, with mean temperature of 29 °C, they were 0.004–0.008 day−1. Obviously, fragmentation rates obtained in our experiment should not be directly translated to those at sea, since in the laboratory environment temperature, light, water movement, biodiversity, 99 Bottles 1.0 crack serial keygen, chemical composition of the seawater e.g. due to metal leaching from the stainless-steel vessel are different. Our results suggest that ER-measurements may be a promising cheap and easy technique to readily monitor the initial steps of the degradation of plastics in water. Additional testing of ER-measurements, for example in freshwater and other environments is essential to asses full application possibilities of this method.

Once holes became visible in the plastic objects, ER measurements could no longer be used to measure further degradation. The holes created a direct seawater connection between the electrode inside, and the electrode outside the plastic object, with very low electrical resistance.

As an indicator of fragmentation, we determined weight loss of the plastic objects after 378–427 days in the microcosm. The observation that plastic materials composed of polymers with a carbon–carbon “C–C” backbone, PE, PS and PP, appeared most recalcitrant with a maximum fragmentation rate of 1% per year may be due to the fact that their degradation is initiated through abiotic photolytic oxidation by UV radiation9,39. The spectrum of the fluorescent lamps in our microcosm included UV light, but the rapid and extensive covering with microbial biofilms may have protected the plastic objects from photolytic degradation, resulting in fragmentation and measurable weight loss. In comparison, the latex balloons had fragmentation rates of about 5% per year in the marine microcosm. Natural latex is a complex coagulation of about 90% polyisoprene with carbohydrates, lipids, proteins, alkaloids, organic acids LicenseCrawler 2.3 Build 2562 Crack Full Version Download amino acids66. The latex polymer consists of a backbone of isoprene monomers connected with C=C double bonds. Previous studies indicated that solar radiation as the most important environmental variable for fragmentation of latex films in freshwater and marine outdoor microcosms67. But in addition, 99 Bottles 1.0 crack serial keygen, latex polymers are known to be degraded by a variety of microorganisms, including marine ones68. Lambert et al. found that latex film exposed in an outdoor microcosm with artificial seawater lost weight at a rate of 50% in 87 days. The big difference to the fragmentation rates of latex material obtained in our microcosm experiment can be related to several factors: (i) a thicker membrane of our latex balloons (0.3 mm) versus the latex films (0.08 mm), 99 Bottles 1.0 crack serial keygen, (ii) exposure to a lower UV dose in the laboratory microcosm (e.g. biofouling), opposed to the outdoor microcosms, (iii) different composition or cross bonding of the latex polymers, and/or (iv) presence of plasticizers and UV absorbers in our balloons. The abundant presence of latex balloons in marine litter suggests fragmentation rates at least are not higher than rates of littering input69. This underpins the importance of testing degradation of real-life consumer plastic materials under realistic marine conditions. The fragmentation rates of PET and PU objects were between 3 and 5% per year. In PET and PU polymers the monomers are connected through ester bonds, which are susceptible to photo-oxidation, hydrolysis and biodegradation9,25,27. Hydrolysis and biodegradation may have caused further weight loss of PET and PU, than that of carbon–carbon backbone polymers, 99 Bottles 1.0 crack serial keygen. We observed the greatest weight losses for the cellulose-containing objects and the compostable plastics. Cellulose and cellulose acetate degrading microorganisms are abundant in the marine environment70,71. Moran et al. reported similar rates of weight loss of cellulosic waste in microcosms with ocean water, 99 Bottles 1.0 crack serial keygen, as we found for the cellulose coffee cups (8% per year) and the cellulose acetate cigarette filters (15% per year), 99 Bottles 1.0 crack serial keygen. Degradation of the disposable bags, labelled compostable according to the EN 13432 standard, occurred, but still 73% to 93% of their original weight remained after a year in the microcosm. Moreover, weight loss of the PLA food trays (fragmentation Halo Infinite gratuit Archives per year) was insignificant. The difference between weight loss of the PLA bags and the PLA food trays is most likely caused by the different PLA grades used for the production of these items58. This demonstrates that the current standard tests based on composting do not reflect the realistic (bio)degradation of plastic materials in the Free YouTube Downloader 4.2.20 environment.

After a year, we detected numerous microplastic particles in the surface water and on the bottom of the microcosm. The synthetic seawater used to prepare the microcosm contained insignificant amounts of microplastics, which indicates fragmentation as a major cause for weight loss of the plastic objects in the microcosm. We did not quantify the extent to which nano- and microplastics formation, and/or mineralization, respectively, contributed to weight loss of the individual plastic items.

Biofilms on the plastics were visible within a month and increased during the experiment, indicating the presence of active growing microbial communities. The biofilm mass on the plastic materials in the microcosm (0.068–0.459 mg dry weight/cm2) was much lower than that on plastic objects which had been submerged for about one year in the Bay of Bengal, India (28–34 mg dry weight/cm2)34,51. Apparently, microbial growth on plastic objects in our closed microcosm system was less abundant than that on plastics exposed in the sea. The fact that one HDPE and two LDPE air pouches sunk after a year in the microcosm is in line with the observation that biofilms can increase the density of plastic objects, causing them to sink52,72. The impact of such ballasting on microplastics, with high surface area Zkbiolock crack serial keygen volume ratio, could be higher than on macroplastics. Recently, it was suggested that there appears to be a fast removal of plastic fragments smaller than a millimeter from the ocean surface water11,14,73. These experiments are congruent with the assumption that ballasting by microbial biofilms may be one explanation of this observation19,74,75.

Bacterial species richness was lowest in biofilms growing on a PE film and highest on the latex balloon. Possibly, the presence of many different organic biodegradable substrates in natural latex might have enhanced biodiversity on the balloon66. In comparison, the composition of the microbial communities growing on the plastic rope and the stainless-steel wall of the microcosm vessel showed the most resemblance. The observation that microbial populations on PS contained less phototrophs and differed most from those on the other plastics may be explained by the fact that PS items float on the water, and the sample for biofilm analysis was taken from the relatively dark underside. The biofilms 99 Bottles 1.0 crack serial keygen the plastic items in our microcosm appear to be significantly less diverse than those observed on plastic objects obtained from marine environments75,76,77,78. This may reflect the relatively simple and homogeneous setting of our artificial laboratory system. The dominance of phototrophic cyanobacteria was obviously sustained by the daily 12/12 h day/night cycle and the clear seawater, allowing the light to easily reach to the bottom of the microcosm. The fact that about 50% of the 16S rRNA genes detected corresponded to Leptolyngbya is significant, since this genus contains pathogenic species. This emphases the observation of other researchers, that plastic objects can act as habitats for pathogenic microorganisms75,77,79,80.

There is a strong need to understand what happens to plastic litter that is entering our oceans. Monitoring campaigns indicate that the amount of plastic found at the sea surface is not increasing proportionally to the estimated inputs of plastic litter and that there appears to be a short residence time of micro-meter sized particles at the sea surface5,6,11,14,21,22,81,82. It has been suggested that the microplastic particles in the oceans may degrade at faster rates when they become smaller, and that they continue to fragment into more hazardous nanoplastics, 99 Bottles 1.0 crack serial keygen, which may be too small to xillsoft video converter ultimate 6.5.2 crack serial keygen with current sampling techniques19,83. Recently it was confirmed that particles in the nanometer range are indeed formed during degradation of PS sheets84. We showed that a decrease in ER values may correlate to the formation of sub-microscopic pores, and thus can indicate the formation of nanoparticles. ER measurements provide thus an interesting tool to quantify the initial stage of fragmentation of plastics in seawater.

Biodegradation of compostable plastic objects in our microcosm occurred at much lower rates than in internationally recognized standard composting tests. The main reason may be that during composting tests degradation processes are routinely examined under optimized conditions that are not representative for marine environments. Our study and accumulating research indicates that even plastic materials labelled as compostable, which are meant to reduce accumulation of plastic waste, may not biodegrade and mineralize within an acceptably short timeframe in marine ecosystems85. Solid experimental data on long term degradation of plastic litter should therefore be collected in laboratory micro- and mesocosm systems under conditions that are realistic for the marine environment in order to best inform our understanding of marine plastic degradability.

Materials and methods

Setup of the marine microcosm

A stainless-steel vessel (0.6 m × 0.6 m × 1.2 m) was filled with 350 L artificial seawater (Fig. 1). The synthetic seawater was prepared by adding WesPro sea salt (www.wesdijk.nl) to demineralized water to obtain an electrical conductivity (EC) of 46 mS/cm on a WTW LF 197 EC meter (WTW Wissenschaftlich Technische Werkstätten, Weilheim, Germany). At about 10 cm below the surface, the seawater in the vessel was recirculated at 6.7 L/min with a pump (Velda Aquarius Universal 600, Groenrijk Malkenschoten, Apeldoorn, Netherlands) to create a mild constant water flow. Four fluorescent lamps (30-W, length 90 cm) were installed in the stainless-steel lid of the vessel to expose the plastics to simulated daylight, including UV-a and UV-b. The fluorescent lamps were two Zoo Med Ocean Sun T8 lamps, each generating 70 photons/m2/s, 99 Bottles 1.0 crack serial keygen, and two Zoomed Repti Sun 5.0 UVB lamps, each generating 60 photons/m2/s on the water surface of the microcosm (www.smulders.nl). Light intensities were measured with a LI-COR LI-192 underwater 99 Bottles 1.0 crack serial keygen sensor with 400–700 nm quantum response, connected to a LI-250 A light meter (CaTec b.v., Wateringen, The Netherlands). The microcosm was subjected to a 12:12 h light and dark regime. The temperature of the seawater was 24 ± 1 °C throughout the experiment. The microcosm was closed with a stain-less steel lid, 99 Bottles 1.0 crack serial keygen, to limit water evaporation and contamination with microplastics from the ambient air.

The microcosm was inoculated with 9 L seawater (conductivity 46 mS/cm) and a variety of plastic materials and stones, collected three days earlier at the North Sea beach at Katwijk aan Zee, The Netherlands. Different types of plastic items with different polymer backbones from household items were collected and added to the marine microcosm, in order to simulate a plastic contaminated marine environment (Fig. 1). The plastics included a selection of conventional thermoplastic and compostable plastic products according to the DIN EN 13,432 standard, 99 Bottles 1.0 crack serial keygen. Of each material subsamples were stored 99 Bottles 1.0 crack serial keygen 4 °C in the dark. A 5 cm cut was made in the packing material air pouches, to let the air escape before they were added to the microcosm.

Electrical resistance (ER) measurements

Electrical resistance (ER) values (Ohm) of plastic materials were measured with a Voltcraft LCR 300 m (www.conrad.nl). The LCR-meter was connected to two 20 cm long messing electrodes, which were inserted inside Viton rubber tubing and fixed in a butyl rubber stopper. The electrode tips were positioned 1 cm apart from each other. At the tip of the electrodes, 2 cm messing was exposed to the seawater. For ER measurements one electrode tip was inserted in seawater inside a plastic bag, cup or bottle, respectively. The other electrode was positioned at the outside in the seawater of the microcosm. In this way, the ER of the plastics were measured by recording the resistance between the electrodes at different frequencies AC current: 100, 120 and 1,000 Hz, respectively. ER measurements at higher frequencies of 10.000 or UltraEdit serial number Archives, respectively, were not consistent and not used for this study. The ER measurements were done in the serial modus (Rs) of the LCR meter. The ER measurements were started 8 days addition after of the plastic objects to the microcosm and at 2 to 5 months’ intervals thereafter. The ER measurements were routinely recorded in triplicate, and the coefficient of variation based on 75 triplicate measurements was 25 ± 2%. The plastics ER values were calculated as follows:

$${ER}_{plastic}= {ER}_{plastic\cdot emerged\cdot in\cdot seawater}-{ER}_{seawater}$$

Volume fraction (Φ) of water

The uptake of water by plastics was estimated by measuring the capacitance (C in nF) immediately after they were added (C start) and just before they were privacy tools Archives s (C end) from the microcosm. The volume fraction of water of the plastics (Φ) was subsequently assessed according to the empirical relation of Brasher and Kinsbury86:

$$\Phi =\frac{{\mathrm{log}}\left({\mathrm{C\,end}}/{\mathrm{C\,start}}\right)}{\mathrm{log}80}$$

Values of water fractions are averages ± standard deviations of capacitance measurements obtained at 100, 120 and 1,000 Hz, respectively.

Dry weight analyses and fragmentation 99 Bottles 1.0 crack serial keygen weight of a selection of the plastic objects was measured before and after 378–427 days of incubation in 99 Bottles 1.0 crack serial keygen microcosm (Table 4). After removal from the microcosm, they were first drained for one minute before measurement of the wet weight of the plastics with the biofilms. Subsequently, the biofilms were carefully removed with a nylon brush34. Then the plastics were rinsed with tap water and incubated overnight in demineralized water to remove traces of seawater salts. Finally, the plastics were swept with a tissue and dried on aluminum foil in a stove at 40 °C, typically for 2 to 5 days, until constant weight. Plastics of more than 1 g were weighed on a Mettler PM 4600 balance, others on a Mettler AE 200 balance (Mettler Toledo, Tiel, Netherlands). The weight loss of 0 – 0.1% found for some PE and PP items confirmed that the biofilm removal procedure did not cause significant degradation of these plastic objects. The percentages loss of dry weight of the plastics were calculated subsequently as:

Full size table

$$ {\mathrm{Dry}}\cdot {\mathrm{weight}}\cdot {\mathrm{loss}} \left(\%\right)=\frac{{\mathrm{W}}_{0}- {\mathrm{W}}_{\mathrm{t}}}{{\mathrm{W}}_{0}*100}$$

where \({W}_{0}\) is the initial dry weight of a plastic sample before incubation, and \({W}_{t}\) the dry weight determined after “t” days incubation in the microcosm. Fragmentation rates were subsequently Jogos de Tabletop de Graça para Baixar as % dry weight loss per year.

Biofilm removal with a toothbrush from the compostable plastic bags, labelled with registration numbers 7P0069, 7P0189 and 7P0204, respectively, was not possible without fragmenting these materials. Therefore, the biofilms from the latter plastics were removed by incubation, with 30% H2O2, overnight at 25 °C, and shaken at 100 rpm. Weight losses of triplicate subsamples of unexposed sheets of 7P0069 and 7P0189 by H2O2 treatment were 1.92 ± 1.0% and 0.094 ± 0.232%, respectively. These values were used as correction factors for dry weight loss analyses of the compostable plastic bags, 99 Bottles 1.0 crack serial keygen. Weight loss of the cigarette filters was corrected for the loss of their paper covers in the microcosm, 99 Bottles 1.0 crack serial keygen, which accounted for 49 ± 20% of their mass.

The biofilm material removed from the plastics was suspended in 100 mL autoclaved synthetic seawater and stored it at 4 °C in the dark for further analyses. The dry weight of the biofilms was determined by filtration of 25 mL subsamples of the biofilm suspensions on pre-weighed cellulose acetate filters with a diameter of 47 mm and a pore size of 0.45 µm (www.merckmillipore.com). The filters were dried in a stove at 40 °C for 3 days until constant weight.

Microplastics

Samples were collected at 389 days after plastic addition to the microcosm. For microplastic sampling, 500 mL Erlenmeyer flasks were washed and immediately sealed with aluminum foil. Water samples (approx. 500 mL each) in triplicate were collected from the left, the middle and the right sections of the microcosm. Samples of buoyant microplastics were obtained by holding the opening of the Erlenmeyer flasks about 2 mm below the water surface. Three water samples were collected by opening the flasks 25 cm below the water surface. Samples at the bottom (50 cm depth) were withdrawn with a 100 mL glass syringe (Sanitex Eterna-Matic interchangeable) moving slowly over the bottom of the microcosm. The samples were stored at 4 °C in Flvto Youtube Downloader License KEY Archives dark. Microplastic particles were filtered from the water samples over a Whatman glass filter (diameter 47 mm, pore size 0.2 µm) and Save flash 4.1 crack serial keygen rinsed with 30 mL H2O2 (30%) followed by 30 mL MilliQ® analytical grade water according to Leslie et al.87.

Identification of microbial populations

Five plastic objects and one biofilm sample scraped from the steel wall with a 50 mL Greiner centrifuge tube (VWR International B.V., Amsterdam, Netherlands) were taken 665 days after starting the microcosm. The samples were kept at − 80 °C until DNA extraction and 16S rRNA gene metabarcoding76,78. DNA was extracted using the Powersoil DNA isolation kit (MOBIO Laboratories, Carlsbad, CA) according to the manufacturer’s instructions. The DNA extracts of all samples were stored at − 20 °C until further processing. The extracted DNA was used for bacterial (V3-V4 16S rRNA gene) taxonomic screening through amplicon sequencing using the Illumina technology (Illumina, San Diego, CA, USA). Fragments were amplified and extended with Illumina specific adaptors by using an amplification and dual-index PCR successively (detailed description in De Tender et al.). Each PCR step was followed by a PCR product clean-up using the CleanPCR reagent kit (MAGBIO, Gaithersburg, MD, USA). Quality of the final libraries was checked using the Qiaxcel Advanced with the Qiaxcel DNA High Resolution kit (QIAGEn, Germantown, MD, USA) and concentrations were measured using the quantus double-stranded DNAassay (Promega, Madison, WI, USA). The final barcoded libraries of each sample were diluted to 10 nM and equally pooled. The resulting library was sequenced on an Illumina MiSeq 2 × 300 bp paired-end by Macrogen (Seoul, South Korea), using 30% PhiX DNA as spike-in. Demultiplexing of the amplicon dataset and barcode removal was done by the sequencing provider. The raw sequence data is available in the NCBI Sequence Read Archive under the accession number PRJNA3743322. The sequence read processing was done as described in detail in76.

Statistical analysis

OTU tables of the 16S V3-V4 rRNA gene amplicon sequencing were analyzed using the QIIME software package (v1.9.0)88. Taxonomy was assigned with the script “assign_taxonomy.py” using the uclust method considering maximum 3 database hits, with the silva v119 97% rep set (provided by QIIME) as reference for the bacterial sequences and UNITE v7 (dynamic) for fungal sequences89,90,91. For the analysis of the bacterial populations, both community diversity and composition were studied. To study community diversity, data was rarefied at 20,000 sequences. Based on this rarefied data, the number of observed OTUs and the Shannon–Wiener diversity index were calculated as an estimation of the community’s richness and diversity. Total community composition was analyzed using the multivariate analysis of the specific R package vegan (version 2.3–2)92. The icloud hack bypass matrix, based on the Bray–Curtis dissimilarity index, was calculated from the OTU table as generated by Usearch for bacterial sequences. This Bray–Curtis dissimilarity matrix was used as input for the Principal Coordinate Analysis (PCoA).

Data availability

All sequence data of this study is available in the NCBI Sequence Read Archive under the accession number PRJNA3743322.

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Upgrading Information Sites

HP 48 Clubs/User Groups

General HP Calculator Sites

The Other Side

Part of the HP Calculator Archive,
Copyright 1997-2021 Eric Rechlin.
Источник: [https://torrent-igruha.org/3551-portal.html]

Scripts with documentation (by date)

Total Size of .r Filessizedir.r
 documentationv:1.0.0
557 bytes
13 Mar 2003Print the total size of all .r files in the current directory.
author: Anonymous

Documentation: by btiffin on 5-May-2007.

TCP port scanneroneliner-tcp-port-scanner.r
 documentationv:1.0.0
850 bytes
20 Jul 2003This is a simple port scanner. Given a TCP address, it will tell you which of the first 100 ports are accessible. The address can be a host name or number. For example, use "localhost" to scan ports on your own machine. You can scan more ports by increasing the number (from 100), or you can scan ranges by using a FOR loop rather than REPEAT.
author: Anonymous

Documentation: by btiffin on 5-May-2007.

POP Email Port Specpopspec.r
 documentation850 bytes
13 Mar 2003POP port specification used to connect to an email 99 Bottles 1.0 crack serial keygen server. All of the mail reading examples use this.
author: [unknown]

Documentation: by btiffin on 5-May-2007.

Trivial Email List Servermailserver.r
 documentationv:1.0.0
1.2 KB
13 Mar 2003As simple as a list server Arquivos Windows Phone Anonymous

Documentation: by btiffin on 5-May-2007.

TSN: Tranched serial number servertsn.r
 documentationv:0.0.1
7.6 KB
30 Apr 2007Quick, Jogos de Explorador de Calabouços de Graça para Baixar way of allocating categorized unique serial numbers
author: Sunanda

Documentation: by sunanda on 30-Apr-2007.

Rename a Fileftprename.r
 documentation411 bytes
13 Mar 2003Rename a file on a server using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Upload a Fileftpup.r
 documentationv:1.0.0
459 bytes
13 Mar 2003Upload a binary file to an FTP server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Upload Several Filesftpupload.r
 documentationv:1.0.0
585 bytes
13 Mar 2003Upload multiple files with FTP using login and password.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Read a Text Fileftpread.r
 documentation412 bytes
13 Mar 2003Read a text file from an FTP server and print it.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Make a directoryftpmakedir.r
 documentation414 bytes
13 Mar 2003Make a file directory on an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Get File Size and Dateftpinfo.r
 documentation498 bytes
13 Mar 2003Get size and date information about an FTP file.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Upload all HTML Filesftphtml.r
 documentationv:1.0.0
642 bytes
13 Mar 2003Upload a group of files to an FTP server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Download a Binary Fileftpdownbin.r
 documentation470 bytes
13 Mar 2003Download a binary file from an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Interactive FTP Downloaderftpdownload.r
 documentation718 bytes
13 Mar 2003Download a group of files from an FTP server, prompting for each file along the way.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Download List of Filesftpdown.r
 documentation536 bytes
13 Mar 2003Download a list of binary files using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Run Script from FTPftpdo.r
 documentation390 bytes
13 Mar 2003Do a REBOL script via FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Read File Directoriesftpdir.r
 documentation500 bytes
13 Mar 2003Read and print directories from an FTP server.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Check for Directoryftpdircheck.r
 documentation455 bytes
13 Mar 2003Check if a filename belongs to a directory using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Delete a File or Directoryftpdel.r
 documentation470 bytes
13 Mar 2003Delete a file or directory from a server using FTP.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Check for a File or Directoryftpcheck.r
 documentation574 bytes
13 Mar 2003Check for the existence of an FTP file or directory.
author: [unknown]

Documentation: by btiffin on 29-Apr-2007.

Append to a Text Fileftpappend.r
 documentationv:1.0.0
471 bytes
13 Mar 2003Append to a text file using FTP.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Transfer REBOL Files to Serverftpallto.r
 documentationv:1.0.0
625 bytes
13 Mar 2003FTP all .r files in the current directory to a server.
author: Anonymous

Documentation: by btiffin on 29-Apr-2007.

Count References on Web Pagescountweb.r
 documentationv:1.0.0
743 bytes
13 Mar 2003Count the number of times a string appears on each of a given set of web pages.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Sends Email via CGI Formcgiemailer.r
 documentationv:1.0.0
855 bytes
13 Mar 2003Uses a Web form to send an email message.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

CGI Emailer Form (HTML Part)cgiemailhtml.r
 documentation1.7 KB
13 Mar 2003HTML form to go with CGI Emailer example (cgiemailer.r).
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

Easy CGI Form Examplecgiform.r
 documentationv:1.0.0
1.1 KB
13 Mar 2003Handles a CGI form and returns its values as a web page. (The associated cgiform.html file contains the form).
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Easy CGI Form (HTML Part)cgiformhtml.r
 documentationv:1.0.0
1.4 KB
13 Mar 2003HTML form to go with Easy CGI example (cgiform.r).
author: Anonymous

Documentation: by JD Design ExpPrint v4.1 crack serial keygen on 28-Apr-2007.

CGI Form with Defaultscgiformobj.r
 discussion
 documentation1.3 KB
13 Mar 2003Handles a CGI form, providing default values for missing fields in the form. Classroom Spy Professional 4.7.13 Full Version a web page. (The associated cgiform.html file contains the form).
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

CGI Comment Articlewebcomment.r
 documentation2.9 KB
13 Mar 2003Run this to create the file used for the cgicomment.r script.
author: Carl Sassenrath

Documentation: by btiffin on 28-Apr-2007.

CGI Web Page Comment Postercgicomment.r
 documentation3.0 KB
13 Mar 2003Allows viewers to add comments to a web page. (needs webcomment.r to create example forms file).
author: Carl Sassenrath

Documentation: by btiffin on 28-Apr-2007.

CGI Form Emailercgimail.r
 documentation736 bytes
13 Mar 2003Emails the contents input into a web CGI form.
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

CGI Form Dumpercgidump.r
 documentation785 bytes
13 Mar 2003Display the contents of a submitted form as a web page. Useful for debugging CGI forms.
author: [unknown]

Documentation: by btiffin on 28-Apr-2007.

Display Black Textblack-text.r
 documentationv:1.0.0
512 bytes
13 Mar 2003Display black text on a white background.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

Images Buttonsbutton-image.r
 documentationv:1.0.0
762 bytes
13 Mar 2003Example of how to make buttons made from images. Clicking on a button updates text in the window.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

A Button with Shortcut Keybutton-key.r
 documentationv:1.0.0
479 bytes
13 Mar 2003Shows how to easily add a shortcut key to a button.
author: Anonymous

Documentation: by btiffin on 28-Apr-2007.

SKIMP: Simple keyword index management programskimp.r
 documentationv:0.0.2
40.3 KB
3 May 2007Simple, fast way of indexing the text content of many documents
author: Sunanda

Documentation: by sunanda on 28-Apr-2007.

periodic tableperiodictable.r
 documentationv:0.9.4
11.9 KB
15 Aug 2007Display a periodic table of the elements as REBOL buttons
author: Brian Tiffin

Documentation: by btiffin on 25-Apr-2007.

Alien Dialectalien.r
 documentationv:1.0.0
1.9 KB
13 Mar 2003It came from outer space
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Alien Dialect Explanationalienexp.r
 documentationv:1.0.0
1.4 KB
13 Mar 2003It came from outer space explained.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

REBOL Alebeer.r
 documentationv:1.0.0
1.3 KB
13 Nov 2003A rich, 99 Bottles 1.0 crack serial keygen, malty, copper brew.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

99 Bottles of Beer Songbeersong.r
 documentationv:1.0.0
813 bytes
13 Mar 2003The correct song. A bit more advanced.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

Binary Data in REBOL Scriptsbin-data.r
 documentationv:1.0.0
8.8 KB
13 Mar 2003Example of how to decode binary data in REBOL scripts This example includes a base-64 encoded image. (See bin-save.r for an example of how to create this file.)
author: Anonymous

Documentation: by btiffin on 99 Bottles 1.0 crack serial keygen colspan="3">Encoding Binary Data in REBOL Scriptsbin-save.r
 documentationv:1.0.0
603 bytes
13 Mar 2003Example of how to save base-64 encoded binary data in REBOL scripts. (See bin-data.r as an example of how to decode the 99 Bottles 1.0 crack serial keygen Anonymous

Documentation: by btiffin on 25-Apr-2007.

Email Blasterblast.r
 documentationv:1.0.0
1.8 KB
13 Mar 2003Send an email to everyone on a spreadsheet of email addresses. Personalize the greeting for each. Keep a log of who was been sent the message.
author: Anonymous

Documentation: by btiffin on 25-Apr-2007.

make-word-listmake-word-list.r
 documentationv:1.0.0
16.5 KB
2 Apr 2007Makes a list of words from a string
author: peter

Documentation: by peterwood on 4-Apr-2007.

Run sequence encoded integer data setsrse-ids.r
 documentationv:0.0.1
7.0 KB
21 Feb 2007Provide an API for compacting/compressing sets of integers
author: christian

Documentation: by sunanda on 21-Feb-2007.

Calculate working days between two dateswork-days.r
 documentationv:0.0.1
1.7 KB
18 Feb 2007Given two dates, and a list of holidays that FOOTBALL MANAGER 2020 crack serial keygen occur between them, returns the number of work days between those two days. With the /non refinement, will return the number of non-working days between the two dates.
author: Sunanda

Documentation: by sunanda on 18-Feb-2007.

Anonymous CGI session servicesacgiss.r
 documentationv:0.0.1
8.1 KB
18 Dec 2006Provide basic cookie support for CGI scripts
author: Sunanda

Documentation: by sunanda on 18-Dec-2006.

File globbing module and dialectfile-list.r
 discussion
 documentationv:0.0.2
30.2 KB
19 Oct 2006Given a file spec, and optional criteria for date, size, and attributes, the FILE-LIST function returns a block of files that match the spec and criteria. It is also a test-bed for how to integrate dialects with one-another. There are sub-dialects for date, size, and attribute tests, and FILE-LIST encapsulates those, along [.]
author: Gregg Irwin

Documentation: by greggirwin on 16-Oct-2006.

VB Like Operator Module/pattern-matcherlike.r
 documentationv:0.0.3
6.7 KB
15 Oct 2006The LIKE? function is a first crack at something like VB's Like operator. i.e. a *very* simple RegEx engine as you would use in shells for file globbing. The real purpose was to help me get acquainted with parse.
author: Gregg Irwin

Documentation: by greggirwin on 16-Oct-2006.

Qtask Markup Language - parser and other common codeqml-base.r
 documentationv:2.46.1
97.1 KB
28 May 2007This program implements the base for QML (Qtask Markup Language) converters (for example it's the base for a QML to XHTML converter used in Qtask), by implementing the parsing of a QML text string into a QML document tree.
author: Gabriele Santilli

Documentation: by gabriele on 28-Aug-2006.

Qtask Markup Language - XHTML emitterxhtml-emitter.r
 documentationv:2.19.1
35.1 KB
28 May 2007This program implements a QML to XHTML converter. The input is a QML document tree (from the QML parser), and the output is XHTML text.
author: Gabriele Santilli

Documentation: by gabriele on 28-Aug-2006.

Qtask Markup Language Editorqml-ed.r
 documentation496 bytes
23 Aug 2006Edit QML files, create HTML from QML
author: Gabriele Santilli

Documentation: by gabriele on 23-Aug-2006.

ImageMagick Supportimagemagick-helper.r
 documentation8.8 KB
23 Aug 2006Support minimal needs for image processing using ImageMagick MagickWand and MagickCore DLLs Note: DLL's 99 Bottles 1.0 crack serial keygen tend to change so this is specifically for version 6.2.9 Note: Original uses only MagickCore DLL. This version required MagickWand DLL because they moved the calls to a different DLL
author: Edgar Tolentino

Documentation: by sunanda on 23-Aug-2006.

Sintezar PM-101 - Phase Manipulation Digital Synthesizerpm-101.r
 documentationv:0.4.0
81.3 KB
23 Jun 2006synthetiser
author: Boleslav Brezovsky

Documentation: by rebolek on 23-Jun-2006.

Textile Parsertextile.r
 documentationv:0.2.0
16.2 KB
16 Jun 2006Transforms Textile-formatted text into HTML
author: Brian Wisti

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Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005

Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: mmwrq@cdc.gov. Type 508 Accommodation and the title of the report in the subject line of e-mail.

Please note:This report has been corrected and replaces the electronic PDF version that was published on December 30, 2005.

Prepared by

Paul A. Jensen, PhD, Lauren A. Lambert, MPH, Michael F. Iademarco, MD, Renee Ridzon, MD

Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention


The material in this report originated in the National Center for HIV, STD, and TB Prevention, Kevin Fenton, MD, PhD, 99 Bottles 1.0 crack serial keygen, Director; and the Division of Tuberculosis Elimination, Kenneth G. Castro, MD, Director.

Corresponding preparer: Paul A. Jensen, 99 Bottles 1.0 crack serial keygen, PhD, Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, 1600 Clifton Rd., NE, MS E-10, Atlanta, GA 30333. Telephone: 404-639-8310; Fax: 404-639-8604; E-mail: pej4@cdc.gov.


Summary

In 1994, CDC published the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994. The guidelines were issued in response to 1) a resurgence of tuberculosis (TB) disease that occurred in the United States in the mid-1980s and early 1990s, 2) the documentation of several high-profile health-care–associated (previously termed "nosocomial") outbreaks related to an increase in the prevalence of TB disease and human immunodeficiency virus (HIV) coinfection, 3) lapses in infection-control practices, 99 Bottles 1.0 crack serial keygen, 4) delays in the diagnosis and treatment of persons with infectious TB disease, and 5) the appearance and transmission of multidrug-resistant (MDR) TB strains. The 1994 guidelines, which followed statements issued in 1982 and 1990, presented recommendations for TB-infection control based on a risk assessment process that classified health-care facilities according to categories of TB risk, with a corresponding series of administrative, environmental, and respiratory-protection control measures.

The TB infection-control measures recommended by CDC in 1994 were implemented widely in health-care facilities in the United States. The result has been a decrease in the number of TB outbreaks in health-care 99 Bottles 1.0 crack serial keygen reported to CDC and a reduction in health-care–associated transmission of Mycobacterium tuberculosis to patients and health-care workers (HCWs). Concurrent with this success, mobilization of the nation's TB-control programs succeeded in reversing the upsurge in reported cases of TB disease, and case rates have declined in the subsequent 10 years. Findings indicate that although the 2004 TB rate was the lowest recorded in the United States since national reporting began in 1953, the declines in rates for 2003 (2.3%) and 2004 (3.2%) were the smallest since 1993. In addition, TB infection rates greater than the U.S. average continue to be reported in certain racial/ethnic populations. The threat of MDR TB is decreasing, and the transmission of M. tuberculosis in health-care settings continues to decrease because of implementation of infection-control measures and reductions in community rates of TB.

Given the changes in epidemiology and a request by the Advisory Council for the Elimination of Tuberculosis (ACET) for review and update of the 1994 TB infection-control document, CDC has reassessed the TB infection-control guidelines for health-care settings. This report updates TB control recommendations reflecting shifts in the epidemiology of TB, advances in scientific understanding, and changes in health-care practice 99 Bottles 1.0 crack serial keygen have occurred in the United States during the preceding decade. In the context of diminished risk for health-care–associated transmission of M. tuberculosis, this document places emphasis on actions to maintain momentum and expertise needed to avert another TB resurgence and to eliminate the lingering threat to HCWs, which is mainly from patients or others with unsuspected and undiagnosed infectious TB disease. CDC prepared the current guidelines in consultation with experts in TB, infection control, environmental control, respiratory protection, and occupational health. The new guidelines have been expanded to address a broader concept; health-care–associated settings go beyond the previously defined facilities. The term "health-care setting" includes many types, such as inpatient settings, outpatient settings, TB clinics, settings in correctional facilities in which health care is delivered, settings in which home-based health-care and emergency medical services are provided, and laboratories handling clinical specimens that might contain M. tuberculosis. The term "setting" has been chosen over the term "facility," used in the previous guidelines, to broaden the potential places for which these guidelines apply.

Introduction

Overview

In 1994, CDC published the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Facilities, 1994 (1). The guidelines were issued in response to 1) a resurgence of tuberculosis (TB) disease that occurred in the United States in the mid-1980s and early 1990s, 2) the documentation of multiple high-profile health-care–associated (previously "nosocomial") outbreaks related to an increase in the prevalence of TB disease and human immunodeficiency virus (HIV) coinfection, 3) lapses in infection-control practices, 4) delays in the diagnosis and treatment of persons with infectious TB disease (2,3), and 5) the appearance and transmission of multidrug-resistant (MDR) TB strains (4,5).

The 1994 guidelines, which followed CDC statements issued in 1982 and 1990 (1,6,7), presented recommendations for TB infection control based on a risk assessment process. In this process, health-care facilities were classified according to categories of TB risk,with a corresponding series of environmental and respiratory-protection control measures.

The TB infection-control measures recommended by CDC in 1994 were implemented widely in health-care facilities nationwide (8–15). As a result, a decrease has occurred in 1) the number of TB outbreaks in health-care settings reported to CDC and 2) health-care–associated transmission of M. tuberculosis to patients and health-care workers (HCWs) (9,16–23). Concurrent with this success, mobilization of the nation's TB-control programs succeeded in reversing the upsurge in reported cases of TB disease, and case rates have declined in the subsequent 10 years (4,5). Findings indicate that although the 2004 TB rate was the lowest recorded in the United States since national reporting began in 1953, the 99 Bottles 1.0 crack serial keygen in rates for 2003 (2.3%) and 2004 (3.2%) were the lowest since 1993. In addition, TB rates higher than the U.S. average continue to be reported in certain racial/ethnic populations (24). The threat of MDR TB is decreasing, and the transmission of M. tuberculosis in health-care settings continues to decrease because of implementation of infection-control measures and reductions in community rates of TB (4,5,25).

Despite the general decline in TB rates in recent years, a marked geographic variation in TB case rates persists, which means that HCWs in different areas face different risks (10). In 2004, case rates varied per 100,000 population: 1.0 in Wyoming, 7.1 in New York, 8.3 in California, and 14.6 in the District of Columbia (26), 99 Bottles 1.0 crack serial keygen. In addition, despite the progress in the United States, the 2004 rate of 4.9 per 100,000 population Fix-It Driver Repair 3.0 Full Version Download higher than the 2000 goal of 3.5. This goal was established as part of the national strategic plan for TB elimination; the final goal is <1 case per 1,000,000 population by 2010 (4,5,26).

Given the changes in epidemiology and a request by the Advisory Council for the Elimination of Tuberculosis (ACET) for review and updating of the 1994 TB infection-control document, CDC has reassessed the TB infection-control guidelines for health-care settings. This report updates TB-control recommendations, reflecting shifts in the epidemiology of TB (27), advances in scientific understanding, and changes in health-care practice that have occurred in the United States in the previous decade (28). In the context of diminished risk for health-care–associated transmission of M. tuberculosis, this report emphasizes actions to maintain momentum and expertise needed to avert another TB resurgence and eliminate the lingering threat to HCWs, which is primarily from patients or other persons with unsuspected and undiagnosed infectious TB disease.

CDC prepared the guidelines in this report in consultation with experts in TB, infection control, environmental control, respiratory protection, and occupational health. This report replaces all previous CDC guidelines for 99 Bottles 1.0 crack serial keygen infection control in health-care settings (1,6,7). Primary references citing evidence-based science are used in this report to support explanatory material and recommendations. Review articles, which include primary references, are used for editorial style and brevity.

The following changes differentiate this report from previous guidelines:

  • The risk assessment process includes the assessment of additional aspects of infection control.
  • The term "tuberculin skin tests" (TSTs) is used instead of purified protein derivative (PPD).
  • The whole-blood interferon gamma release assay (IGRA), QuantiFERON(r)-TB Gold test (QFT-G) (Cellestis Limited, 99 Bottles 1.0 crack serial keygen, Carnegie, Victoria, Australia), is a Food and Drug Administration (FDA)–approved in vitro cytokine-based assay for cell-mediated immune reactivity to M. tuberculosis and might be used instead of TST in TB screening programs for HCWs. This IGRA is an example of a blood assay for M. tuberculosis (BAMT).
  • The frequency of TB screening for HCWs has been decreased in various settings, and the criteria for determination of screening frequency have been changed.
  • The scope of settings in which the guidelines apply has been broadened to include laboratories and additional outpatient and nontraditional facility-based settings.
  • Criteria for serial testing for M. tuberculosis infection of HCWs are more clearly Vray license server Archives. In certain settings, this change will decrease the number of HCWs who need serial TB screening.
  • These recommendations usually apply to an entire health-care setting rather than areas within a setting.
  • New terms, airborne infection precautions (airborne Recovery Tools Archives - Page 2 of 4 - MASTERkreatif and airborne infection isolation room (AII room), are introduced.
  • Recommendations for annual respirator training, 99 Bottles 1.0 crack serial keygen, initial respirator fit testing, and periodic respirator fit testing have been added.
  • The evidence of the need for respirator fit testing is summarized.
  • Information on ultraviolet germicidal irradiation (UVGI) and room-air recirculation units has been expanded.
  • Additional information regarding MDR TB and HIV infection has been included.

In accordance with relevant local, state, 99 Bottles 1.0 crack serial keygen, and federal laws, implementation of all recommendations must safeguard the confidentiality and civil rights of all HCWs and patients who have been infected with M. tuberculosis and who developTB disease.

The 1994 CDC guidelines were aimed primarily at hospital-based facilities, which frequently refer to a physical building or set of buildings. The 2005 guidelines have been expanded to address a broader concept. Setting has been chosen instead of "facility" to expand the scope of potential places for which these guidelines apply (Appendix A). "Setting" is used to describe any relationship (physical or organizational) in which HCWs might share air space with persons with TB disease or in which HCWs might be in contact with clinical specimens. Various setting types might be present in a single facility. Health-care settings include inpatient settings, outpatient settings, and nontraditional facility-based settings.

  • Inpatient settings include patient rooms, emergency departments (EDs), intensive care units (ICUs), surgical suites, laboratories, laboratory procedure areas, bronchoscopy suites, sputum induction or inhalation therapy rooms, autopsy suites, and embalming rooms.
  • Outpatient settings include TB treatment facilities, medical offices, ambulatory-care settings, dialysis units, and dental-care settings.
  • Nontraditional facility-based settings include emergency medical service (EMS), medical settings in correctional facilities (e.g., prisons, jails, 99 Bottles 1.0 crack serial keygen, and detention centers), home-based health-care and outreach settings, 99 Bottles 1.0 crack serial keygen, long-term–care settings (e.g., hospices, skilled nursing facilities), and homeless shelters. Other settings in which suspected and confirmed TB patients might be encountered might include cafeterias, general stores, kitchens, laundry areas, maintenance shops, pharmacies, and law enforcement settings.

HCWs Who Should Be Included in a TB Surveillance Program

HCWs refer to all paid and unpaid persons working in health-care settings who have the potential for exposure to M. tuberculosis through air space shared with persons with infectious TB disease. Part time, temporary, contract, and full-time HCWs should be included in TB screening programs. All HCWs who have duties that involve face-to-face contact with patients with suspected or confirmed TB disease (including transport staff) should be included in a TB screening program.

The following are HCWs who might be included in a TB screening program:

  • Administrators or managers
  • Bronchoscopy staff
  • Chaplains
  • Clerical staff
  • Computer programmers
  • Construction staff
  • Correctional officers
  • Craft or repair staff
  • Dental staff
  • Dietician or dietary staff
  • ED staff
  • Engineers
  • Food service staff
  • Health aides
  • Health and safety staff
  • Housekeeping or custodial staff
  • Homeless shelter staff
  • Infection-control staff
  • ICU staff
  • Janitorial staff
  • Laboratory staff
  • Maintenance staff
  • Morgue staff
  • Nurses
  • Outreach staff
  • Pathology laboratory staff
  • Patient transport staff, including EMS
  • Pediatric staff
  • Pharmacists
  • Phlebotomists
  • Physical and occupational therapists
  • Physicians (assistant, attending, fellow, resident, 99 Bottles 1.0 crack serial keygen, or intern), including
    — anesthesiologists
    — pathologists
    — psychiatrists
    — psychologists
  • Public health educators or teachers
  • Public safety staff
  • Radiology 99 Bottles 1.0 crack serial keygen Respiratory therapists
  • Scientists
  • Social workers
  • Students (e.g., medical, nursing, technicians, and allied health)
  • Technicians (e.g., health, laboratory, radiology, and animal)
  • Veterinarians
  • Volunteers

In addition, HCWs who perform any of the following activities should also be included in the TB screening program.

  • entering patient rooms or treatment rooms whether or not a patient is present;
  • participating in aerosol-generating or aerosol-producing procedures (e.g., bronchoscopy, sputum induction, and administration of aerosolized medications) (29);
  • participating in suspected or confirmed M. tuberculosis specimen processing; or
  • installing, maintaining, or replacing environmental controls in areas in which persons with TB disease are encountered.

Pathogenesis, Epidemiology, and Transmission of M. tuberculosis

M. tuberculosis is carried in airborne particles called droplet nuclei that can be generated when 99 Bottles 1.0 crack serial keygen who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing (30,31). The particles are approximately 1–5 µm; normal air currents can keep them airborne for prolonged periods and spread them throughout a room or building (32). M. tuberculosis is usually transmitted only through air, not by surface contact. After the droplet nuclei are in the alveoli, local infection might be established, followed by dissemination to draining lymphatics and hematogenous spread throughout the body (33). Infection occurs when a susceptible person inhales droplet nuclei containing M, 99 Bottles 1.0 crack serial keygen. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, 99 Bottles 1.0 crack serial keygen, and bronchi to reach the alveoli. Persons with TB pleural effusions might also have concurrent unsuspected pulmonary or laryngeal TB disease.

Usually within 2–12 weeks after initial infection with M, 99 Bottles 1.0 crack serial keygen. tuberculosis, the 99 Bottles 1.0 crack serial keygen response limits additional multiplication of the tubercle bacilli, and immunologic test results for M. tuberculosis infection become positive, 99 Bottles 1.0 crack serial keygen. However, certain bacilli remain in the body and are viable for multiple years. This condition is referred to as latent tuberculosis infection (LTBI). Persons with LTBI are asymptomatic (they have no symptoms of TB disease) and are not infectious.

In the United States, LTBI has been diagnosed traditionally based on a PPD-based TST result after TB disease has been excluded. In vitro cytokine-based immunoassays for the detection of M. tuberculosis infection have been the focus of intense research and development. One such blood assay for M. tuberculosis (or BAMT) is an IGRA, the QuantiFERON(r)-TB test (QFT), and the subsequently developed version, 99 Bottles 1.0 crack serial keygen, QFT-G. The QFT-G measures cell-mediated immune responses to peptides from two M. tuberculosis proteins that are not present in any Bacille Calmette-Guérin (BCG) vaccine strain and that are absent from the majority of nontuberculous mycobacteria (NTM), also known as mycobacteria other than TB (MOTT). QFT-G was approved by FDA in 2005 and is an available option for detecting M. tuberculosis infection. CDC recommendations for the United States regarding QFT and QFT-G have been published (34,35). Because this field is rapidly evolving, in this report, BAMT will be used generically to refer to the test currently available in the United States.

Additional cytokine-based immunoassays are under development and might be useful in the diagnosis of M. tuberculosis infection. Future FDA-licensed products in combination with CDC-issued recommendations might provide additional diagnostic alternatives. The latest CDC recommendations for guidance on diagnostic use of these and related technologies are available at http://www.cdc.gov/nchstp/tb/pubs/mmwr/html/Maj_guide/Diagnosis.htm.

Typically, approximately 5%–10% of persons who become infected with M. tuberculosis and who are not treated for LTBI will develop TB disease during their lifetimes (1). The risk for progression of LTBI to TB disease is highest during the first several years after infection (36–38).

Persons at Highest Risk for Exposure to and Infection with M. tuberculosis

Characteristics of persons exposed to M. tuberculosis that might affect Windows 7 Activator Archives - Download 6 best Windows 7 Activator 2019 risk for infection are not as well defined. The probability that a person who is exposed to M. tuberculosis will become infected depends primarily on the concentration of infectious droplet nuclei in the air and the duration of exposure to a person with infectious TB disease. The closer the proximity and the longer the duration of exposure, the higher the risk is for being infected.

Close contacts are persons who share the same air space in a household or other enclosed environment 99 Bottles 1.0 crack serial keygen a prolonged period (days or weeks, not minutes or hours) with a person with pulmonary TB disease (39). A suspect TB patient is a person in whom a diagnosis of TB disease is being considered, whether or not antituberculosis treatment has been started. Persons generally should not remain a suspect TB patient for >3 months (30,39).

In addition to close contacts, the following persons are also at higher risk for exposure to and infection with M. tuberculosis. Persons listed who are also close contacts should be top priority.

  • Foreign-born persons, including children, especially those who have arrived to the United States within 5 years after moving from geographic areas with a high incidence of TB disease (e.g., Africa, Asia, Eastern Europe, Latin America, and Russia) or who frequently travel to countries with a high prevalence of TB disease.
  • Residents and employees of congregate settings that are high risk (e.g., correctional facilities, long-term–care facilities [LTCFs], and homeless shelters).
  • HCWs who serve patients who are at high risk.
  • HCWs with unprotected exposure to a patient with TB disease before the identification and correct airborne precautions of the patient.
  • Certain populations who are medically underserved and who have low income, as defined locally.
  • Populations at high risk who are defined locally as having an increased incidence of TB disease.
  • Infants, children, and adolescents exposed to adults in high-risk categories.

Persons Whose Condition is at High Risk for Progression From LTBI to TB Disease

The following persons are at high risk for progressing from LTBI to TB disease:

  • persons infected with HIV;
  • persons infected with M. tuberculosis within the previous 2 years;
  • infants and children aged <4 years;
  • persons with any of the following clinical conditions or other immunocompromising conditions
    — silicosis,
    — diabetes mellitus,
    — chronic renal failure,
    — certain hematologic disorders (leukemias and lymphomas),
    — other specific malignancies (e.g., carcinoma of the head, neck, or lung),
    — body weight ≥10% below ideal body weight,
    — prolonged corticosteroid use,
    — other immunosuppressive treatments (including tumor necrosis factor-alpha [TNF-α] antagonists),
    — organ transplant,
    — end-stage renal disease (ESRD), and
    — intestinal bypass or gastrectomy; and
  • persons with a history of untreated or inadequately treated TB disease, 99 Bottles 1.0 crack serial keygen, including persons with chest radiograph findings consistent with previous TB disease.

Persons who use tobacco or alcohol (40,41), illegal drugs, including injection drugs and crack cocaine (42–47), might also be at increased risk for infection and disease, 99 Bottles 1.0 crack serial keygen. However, because of multiple other potential risk factors that commonly occur among such persons, use of these substances has been difficult to identify as separate risk factors.

HIV infection is the greatest risk factor for progression from LTBI to TB disease (22,39,48,49). Therefore, voluntary HIV counseling, testing, and referral should be routinely offered to all persons at risk for LTBI (1,50,51). Health-care settings should be particularly aware of the need for preventing transmission of M. tuberculosis in settings in which persons infected with HIV might be encountered or might work (52).

All HCWs should be informed regarding the risk for developing TB disease after being infected with M. tuberculosis (1). However, the rate of TB disease among persons who are HIV-infected and untreated for LTBI in the United States is substantially higher, ranging from 1.7–7.9 TB cases per 100 person-years (53). Persons infected with HIV who are already severely immunocompromised and who become newly infected with M. tuberculosis have a greater risk for developing TB disease, compared with newly infected persons 99 Bottles 1.0 crack serial keygen HIV infection (39,53–57).

The percentage of patients with TB disease who are HIV-infected is decreasing in the United States because of improved infection-control practices and better diagnosis and treatment of both HIV infection and TB. With increased voluntary HIV counseling and testing and the increasing use of treatment for LTBI, TB disease will probably continue to decrease among HIV-infected persons in the United States (58). Because the risk for disease is particularly high among HIV-infected persons with M. tuberculosis infection, HIV-infected contacts of persons with infectious pulmonary or laryngeal TB disease must be evaluated for M. tuberculosis infection, including the exclusion of TB disease, as soon as possible after learning of exposure (39,49,53).

Vaccination with BCG probably does not affect the risk for infection after exposure, but it might decrease the risk for progression from infection with M. tuberculosis to TB disease, preventing the development of miliary and meningeal disease in infants and young children (59,60). Although HIV infection increases the likelihood of progression from LTBI to TB disease (39,49), whether HIV infection increases the risk for becoming infected if exposed to M. tuberculosis is not known.

Characteristics of a Patient with TB Disease That Increase the Risk for Infectiousness

The following characteristics exist in a patient with TB disease that increases the risk for infectiousness:

  • presence of cough;
  • cavitation on chest radiograph;
  • positive acid-fast bacilli (AFB) sputum smear result;
  • respiratory tract disease with involvement of the larynx (substantially infectious);
  • respiratory tract disease with involvement of the lung or pleura (exclusively pleural involvement is less infectious);
  • failure to cover the mouth and nose when coughing;
  • incorrect, lack of, or short duration of antituberculosis treatment; and
  • undergoing cough-inducing or aerosol-generating procedures (e.g., bronchoscopy, sputum induction, and administration of aerosolized medications) (29).

Environmental Factors That Increase the Risk for Probability of Transmission of M. tuberculosis

The probability of the risk for transmission of M. tuberculosis is increased as a result of various environmental factors.

  • Exposure to TB in small, enclosed spaces.
  • Inadequate local or general ventilation that results in insufficient dilution or removal of infectious droplet nuclei.
  • Recirculation of air containing infectious droplet nuclei.
  • Inadequate cleaning and disinfection of medical equipment.
  • Improper procedures for handling specimens.

Risk for Health-Care–Associated Transmission of M. tuberculosis

Transmission of M. tuberculosis is a risk in health-care settings (57,61–79). The magnitude of the risk varies by setting, occupational group, prevalence of TB in the community, patient population, and effectiveness of TB infection-control measures. Health-care–associated transmission of M. tuberculosis has been linked to close contact with persons with TB disease during aerosol-generating or aerosol-producing procedures, including bronchoscopy (29,63,80–82), endotracheal intubation, suctioning (66), other respiratory procedures (8,9,83–86), open abscess irrigation (69,83), autopsy (71,72,77), sputum induction, and aerosol treatments that induce coughing (87–90).

Of the reported TB outbreaks in health-care settings, multiple outbreaks involved transmission of MDR TB strains to both patients and HCWs (56,57,70,87,91–94). The majority of the patients and certain HCWs were HIV-infected, and progression to TB and MDR TB disease was rapid. Factors contributing to these outbreaks included delayed diagnosis of TB disease, delayed initiation and inadequate airborne precautions, lapses in AII practices and precautions for cough-inducing and aerosol-generating procedures, and lack of adequate respiratory protection. Multiple studies suggest that the decline in health-care–associated transmission observed in specific institutions is associated with the rigorous implementation of infection-control measures (11,12,18–20,23,95–97). Because various interventions were implemented simultaneously, the effectiveness of each intervention could not be determined.

After the release of the 1994 CDC infection-control guidelines, 99 Bottles 1.0 crack serial keygen, increased implementation of recommended infection-control measures occurred and was documented in multiple national surveys (13,15,98,99). In a survey of approximately 1,000 hospitals, a TST program was present in nearly all sites, and 70% reported having an AII room (13). Other surveys have documented improvement in the proportion of AII rooms meeting CDC criteria and proportion of HCWs using CDC-recommended respiratory protection and receiving serial TST (15,98). A survey of New York City hospitals with high caseloads of TB disease indicated 1) a decrease in the time that patients with TB disease spent in EDs before being transferred to a hospital room, 2) an increase in the proportion of patients initially placed in AII rooms, 3) an increase in the proportion of patients started on recommended antituberculosis treatment and reported to the local or state health department, and 4) an increase in the use of recommended respiratory protection and environmental controls (99). Reports of increased implementation of recommended TB infection controls combined with decreased reports of outbreaks of TB disease in health-care settings suggest that the recommended controls are effective in reducing and preventing health-care–associated transmission of M. tuberculosis (28).

Less information is available regarding the implementation of CDC-recommended TB infection-control measures in settings other than hospitals, 99 Bottles 1.0 crack serial keygen. One study identified major barriers to implementation that contribute to the costs of a TST program in health departments and hospitals, including personnel costs, HCWs' time off from work for TST administration and reading, and training and education of HCWs (100). Outbreaks have occurred in outpatient settings (i.e., private physicians' offices and pediatric settings) where the guidelines were not followed (101–103). CDC-recommended TB infection-control measures are implemented in correctional facilities, and certain variations might relate to resources, expertise, and oversight (104–106).

Fundamentals of TB Infection Control

One of the most critical risks for health-care–associated transmission of M. tuberculosis in health-care settings is from patients with unrecognized TB disease who are not promptly handled with appropriate airborne precautions (56,57,93,104) or who are moved from an AII room too soon (e.g., patients with unrecognized TB and MDR TB) (94). In the United States, the problem of MDR TB, which was amplified by health-care–associated transmission, has been substantially reduced by the use of standardized antituberculosis treatment regimens in the initial phase of therapy, Similar And Duplicate File Finder 6.0 crack serial keygen drug-susceptibility testing, directly observed therapy (DOT), and improved infection-control practices (1). DOT is an adherence-enhancing strategy in which an HCW or other specially trained health professional watches a patient swallow each dose of medication and records the dates that the administration was observed. DOT is the standard of care for all patients with TB disease and should be used for all doses during the course of therapy for TB disease and for LTBI whenever feasible.

All health-care 99 Bottles 1.0 crack serial keygen need a TB infection-control program designed to ensure prompt detection, airborne precautions, and treatment of persons who have suspected or confirmed TB disease (or prompt referral of persons who have suspected TB disease for settings in which persons with TB disease are not expected to be encountered). Such a program is based on a three-level hierarchy of controls, including administrative, environmental, and respiratory protection (86,107,108).

Administrative Controls

The first and most important level of TB controls is the use of administrative measures to reduce the risk for exposure to persons who might have TB disease. Administrative controls consist of the following activities:

  • assigning responsibility for TB infection control in the setting;
  • conducting a TB risk assessment of the setting;
  • developing and instituting a written TB infection-control plan to ensure prompt detection, airborne precautions, and treatment of persons who have suspected or confirmed TB disease;
  • ensuring the timely availability of recommended laboratory processing, testing, 99 Bottles 1.0 crack serial keygen, and reporting of results to the ordering physician and infection-control team;
  • implementing effective work practices for the management of patients with suspected or confirmed TB disease;
  • ensuring proper cleaning and sterilization or disinfection of potentially contaminated equipment (usually endoscopes);
  • training and educating HCWs regarding TB, with specific focus on prevention, transmission, and symptoms;
  • screening and evaluating HCWs who are at risk for TB disease or who might be exposed to M. tuberculosis (i.e., TB screening program);
  • applying epidemiologic-based prevention principles, including the use of setting-related infection-control data;
  • using appropriate signage advising respiratory hygiene and cough etiquette; and
  • coordinating efforts with the local or state health department.

HCWs with TB disease should be allowed to return to work when they 1) have had three negative AFB sputum smear results (109–112) collected 8–24 hours apart, with at least one being an early morning specimen because respiratory secretions pool overnight; and 2) have responded to antituberculosis treatment that will probably be effective based on susceptibility results. In addition, HCWs with TB disease should be allowed to return to work when a physician knowledgeable and experienced in managing TB disease determines that HCWs are noninfectious (see Treatment Procedures for LTBI and TB Disease). Consideration should also be given to the type of setting and the potential risk to patients (e.g., general medical office versus HIV clinic) (see Supplements, Estimating the Infectiousness of a TB Patient; Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease).

Environmental MiniTool Partition Wizard 12.5 Crack & License Key Full Free Download second level of the hierarchy is the use of environmental controls to prevent the spread and reduce the concentration of infectious droplet nuclei in ambient air.

Primary environmental controls consist of controlling the source of infection by using local exhaust ventilation (e.g., hoods, tents, or booths) and diluting and removing contaminated air by using general ventilation.

Secondary environmental controls consist of controlling the airflow to prevent contamination of air in areas adjacent to the source (AII rooms) and cleaning the air by using high efficiency particulate air (HEPA) filtration or UVGI.

Respiratory-Protection Controls

The first two control levels minimize the number of areas in which exposure to M. tuberculosis might occur and, therefore, minimize the number of persons exposed. These control levels also reduce, but do not eliminate, the risk for exposure in the limited areas in which exposure can still occur. Because persons entering these areas might be exposed to M, 99 Bottles 1.0 crack serial keygen. tuberculosis, the third level of the hierarchy is the use of respiratory protective equipment in situations that pose a high risk for exposure. Use of respiratory protection can further reduce risk for exposure of HCWs to infectious droplet nuclei that have been expelled into the air from a patient with infectious TB disease (see Respiratory Protection). The following measures can be taken to reduce the risk for exposure:

  • implementing a respiratory-protection program,
  • training HCWs on respiratory protection, and
  • training patients on respiratory hygiene and cough etiquette procedures.

Relevance to Biologic Terrorism Preparedness

MDR M, 99 Bottles 1.0 crack serial keygen. tuberculosis is classified as a category C agent of biologic terrorism (113). Implementation of the 99 Bottles 1.0 crack serial keygen infection-control guidelines described in this document is essential for preventing and controlling transmission of M. tuberculosis in health-care settings. Additional information is at http://www.bt.cdc.gov and http://www.idsociety.org/bt/toc.htm (114).

Recommendations for Preventing Transmission of M. tuberculosis in Health-Care Settings

TB Infection-Control Program

Every health-care setting should have a TB infection-control plan that is part of an overall infection-control program. The specific details of the TB infection-control program will differ, depending on whether patients with suspected or confirmed TB disease might be encountered in the setting or whether patients with suspected or confirmed TB disease will be transferred to another health-care setting. Administrators making this distinction should obtain medical and epidemiologic consultation from state and local health departments.

TB Infection-Control Program for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

The TB infection-control program should consist of administrative controls, environmental controls, and a respiratory-protection program. Every setting in which services are provided to persons who have suspected or confirmed infectious TB disease, including laboratories and nontraditional facility-based settings, should have a TB infection-control plan. The following steps should be taken to establish a TB infection-control program in these settings:

  1. Assign supervisory responsibility for the TB infection-control program to a designated person or group with expertise in LTBI and TB disease, infection control, occupational health, environmental controls, and respiratory protection. Give the supervisor or supervisory body the support and authority to conduct a TB risk assessment, implement and enforce TB infection-control policies, and ensure recommended training and education of HCWs.
    — Train the persons responsible for implementing and enforcing the TB infection-control program.
    — Designate one person with a back-up as the TB resource person to whom questions and problems should be addressed, if supervisory responsibility is assigned to a committee.
  2. Develop a written TB 99 Bottles 1.0 crack serial keygen plan that outlines a protocol for the prompt recognition and initiation of airborne precautions of persons with suspected or confirmed TB disease, and update it annually.
  3. Conduct a problem evaluation (see Problem Evaluation) if a case of suspected or confirmed TB disease is not promptly recognized and appropriate airborne precautions not initiated, or if administrative, environmental, or respiratory-protection controls fail.
  4. Perform a contact investigation in collaboration with the local or state health department if health-care–associated transmission of M. tuberculosis is suspected (115). Implement and monitor corrective action.
  5. Collaborate with the local or state health department to develop administrative controls consisting of the risk assessment, the written TB infection-control plan, management of 99 Bottles 1.0 crack serial keygen with suspected or confirmed TB disease, training and education of HCWs, screening and evaluation of HCWs, problem evaluation, and coordination.
  6. Implement and maintain environmental controls, including AII room(s) (see Environmental Controls).
  7. Implement a respiratory-protection program.
  8. Perform ongoing training and education of HCWs (see Suggested Components of an Initial TB Training and Education Program for HCWs).
  9. Create a plan for accepting patients 99 Bottles 1.0 crack serial keygen have suspected or confirmed TB disease if they are transferred from another setting.

TB Infection-Control Program for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

Settings in which TB patients might stay before transfer should still have a TB infection-control program in place consisting of administrative, environmental, and respiratory-protection controls. The following steps should be taken to establish a TB infection-control program in these settings:

  1. Assign responsibility for the TB infection-control program to appropriate personnel.
  2. Develop a written TB infection-control plan that outlines a protocol for the prompt recognition and transfer of persons who have suspected or confirmed TB disease to another health-care setting. The plan should indicate procedures to follow to separate persons with suspected or confirmed infectious TB disease from 99 Bottles 1.0 crack serial keygen persons in the setting until the time of transfer. Evaluate the plan annually, if possible, to ensure that the setting remains one in which persons who have suspected or confirmed TB disease are not encountered and that they are promptly transferred.
  3. Conduct a problem evaluation (see Problem Evaluation) if a case of suspected or confirmed TB disease is not promptly recognized, separated from others, and transferred.
  4. Perform an investigation in collaboration with the local or state health department if health-care–associated transmission of M. tuberculosis is suspected.
  5. Collaborate with the local or state health department to develop administrative controls consisting of the risk assessment and the written TB infection-control plan.

TB Risk Assessment

Every health-care setting should conduct initial and ongoing evaluations of the risk for transmission of M. tuberculosis, regardless of whether or not patients with suspected or confirmed TB disease are expected to be encountered in the setting. The TB risk assessment determines the types of administrative, environmental, and respiratory-protection controls needed for a setting and serves as an ongoing evaluation tool of the quality of TB infection control and for the identification of needed improvements in infection-control measures. Part of the risk assessment is similar to a program review that is conducted by the local TB-control program (42). The TB Risk 99 Bottles 1.0 crack serial keygen Worksheet (Appendix B) can be used as a guide for conducting a risk assessment. This worksheet frequently does not specify values for acceptable performance indicators because of the lack of scientific data.

TB Risk Assessment for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

The initial and ongoing risk assessment for these settings should consist of the following steps:

  1. Review the community profile of TB disease in collaboration with the state or local health department.
  2. Consult the local or state TB-control program to obtain epidemiologic surveillance data necessary to conduct a TB risk assessment for the health-care setting.
  3. Review the number of patients with suspected or confirmed TB disease who have been encountered in the setting during at least the previous 5 years.
  4. Determine if persons with unrecognized TB disease have been admitted to or were encountered in the setting during the previous 5 years.
  5. Determine which HCWs need to be included in a TB screening program and the frequency of screening (based on risk classification) (Appendix C).
  6. Ensure the prompt recognition and evaluation of suspected episodes of health-care–associated transmission of M. tuberculosis.
  7. Identify areas in the setting with an increased risk for health-care–associated transmission of M. tuberculosis, and target them for improved TB infection controls.
  8. Assess the number of AII rooms needed for the setting. The risk classification for the setting should help to make this determination, depending on the number of TB patients examined. At least one AII room is needed for settings in which TB patients stay while they are being treated, and additional AII rooms might be needed, depending on the magnitude of patient-days of cases of suspected or confirmed TB disease. Additional AII rooms might be considered if options are limited for transferring patients with suspected or confirmed TB disease to other settings with AII rooms.
  9. Determine the types of environmental controls needed other than AII rooms (see TB Airborne Precautions).
  10. Determine which HCWs need to be included in the respiratory-protection program.
  11. Conduct periodic reassessments (annually, if possible) to ensure
    — proper implementation of the TB infection-control plan,
    — prompt detection and evaluation of suspected TB cases,
    — prompt initiation of airborne 99 Bottles 1.0 crack serial keygen of suspected infectious TB cases,
    — recommended medical management of patients with suspected or confirmed TB disease (31),
    — functional environmental controls,
    — implementation of the respiratory-protection program, and
    — ongoing HCW training and education regarding TB.
  12. Recognize and correct lapses in infection control.

TB Risk Assessment for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

The initial and ongoing risk assessment for these settings should consist of the following steps:

  1. Review the community profile of TB disease in collaboration with the local or state health department.
  2. Consult the local or state TB-control program to obtain ESET Internet Security crack serial keygen surveillance data necessary to conduct a TB risk assessment for the health-care setting.
  3. Determine if persons with unrecognized TB disease were encountered in the setting during the previous 5 years.
  4. Determine if any HCWs need to be included in the TB screening program.
  5. Determine the types of environmental controls that are currently in place, and determine if any are needed in the setting (Appendices A and D).
  6. Document procedures that ensure the prompt recognition and evaluation of suspected episodes of health-care–associated transmission of M. tuberculosis.
  7. Conduct periodic reassessments (annually, if possible) to ensure 1) proper implementation of the TB infection-control plan; 2) prompt detection and evaluation of suspected TB cases; 3) prompt initiation of airborne precautions of suspected infectious TB cases before transfer; 4) prompt transfer of suspected infectious TB cases; 5) proper functioning of environmental controls, as applicable; and 6) ongoing TB training and education for HCWs.
  8. Recognize and correct lapses in infection control.

Use of Risk Classification to Determine Need for TB Screening and Frequency of Screening HCWs

Risk classification should be used as part of the risk assessment to determine the need for a TB screening program for HCWs and the frequency of screening (Appendix C). A risk classification usually should be determined for the entire setting, 99 Bottles 1.0 crack serial keygen. However, in certain settings (e.g., health-care organizations that encompass multiple sites or types of services), specific areas defined by geography, functional units, patient population, job type, or location within the setting might have separate risk classifications. Examples of assigning risk 99 Bottles 1.0 crack serial keygen have been provided (see Risk Classification Examples).

TB Screening Risk Classifications

The three TB screening risk classifications are low risk, medium risk, and potential ongoing transmission. The classification of low risk should be applied to settings in which persons with TB disease are not expected to be encountered, and, therefore, exposure to M. tuberculosis is unlikely. This classification should also be applied to HCWs who will never be exposed to persons with TB disease or to clinical specimens that might contain M. tuberculosis.

The classification of medium risk should be applied to settings in which the risk assessment has determined that HCWs will or will possibly be exposed to persons with TB disease or to clinical specimens that might contain M. tuberculosis.

The classification of potential ongoing transmission should be temporarily applied to any setting (or group of HCWs) if evidence suggestive of person-to-person (e.g., patient-to-patient, patient-to-HCW, HCW-to-patient, or HCW-to-HCW) transmission of M. tuberculosis has occurred in the setting during the preceding year. Evidence of person-to-person transmission of M. tuberculosis includes 1) clusters of TST or BAMT conversions, 2) HCW with confirmed TB disease, 3) increased rates of TST or BAMT conversions, 4) unrecognized TB disease in patients or HCWs, or 5) recognition of an identical strain of M. tuberculosis in patients or HCWs with TB disease identified by deoxyribonucleic acid (DNA) fingerprinting.

If uncertainty exists regarding whether to classify a setting as low risk or medium risk, the setting typically should be classified as medium 99 Bottles 1.0 crack serial keygen Screening Procedures for Settings (or HCWs) Classified as Low Risk

  • All HCWs should receive baseline TB screening upon hire, using two-step TST or a single BAMT to test for infection 99 Bottles 1.0 crack serial keygen M. tuberculosis.
  • After baseline testing for infection with M. tuberculosis, additional TB screening is not necessary unless an exposure to M. tuberculosis occurs.
  • HCWs with a baseline positive or newly positive test result for M. tuberculosis infection (i.e., TST or BAMT) or documentation of treatment for LTBI or TB disease should receive one chest radiograph result to exclude TB disease (or an interpretable copy within a reasonable time frame, such as 6 months). Repeat radiographs are not needed unless symptoms or signs of TB disease develop or unless recommended by a clinician (39,116).

TB Screening Procedures for Settings (or HCWs) Classified as Medium Risk

  • All HCWs should receive baseline TB screening upon hire, using two-step TST or a single BAMT to test for infection with M. tuberculosis.
  • After baseline testing for infection with M. tuberculosis, HCWs should receive TB screening annually (i.e., symptom screen for all HCWs and testing for infection with M. tuberculosis for HCWs with baseline negative test results).
  • HCWs with a baseline positive or newly positive test result for M. tuberculosis infection or documentation of previous treatment for LTBI or TB disease should receive one chest radiograph result to exclude TB disease. Instead of participating in serial testing, HCWs should receive a symptom screen annually. This screen should be accomplished by educating the HCW about symptoms of TB disease and instructing the HCW to report any such symptoms immediately to the occupational health unit. Treatment for LTBI should be considered in accordance with CDC guidelines (39).

TB Screening Procedures for Settings (or HCWs) Classified as Potential Ongoing Transmission

  • Testing for infection with M. tuberculosis might need to be performed every 8–10 weeks until lapses in infection control have been corrected, and no additional evidence of ongoing transmission is apparent.
  • The classification of potential ongoing transmission should be used as a temporary classification only. It warrants immediate investigation and corrective steps. After a determination that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Settings Adopting BAMT for 99 Bottles 1.0 crack serial keygen in TB Screening

Settings that use TST as part of TB screening and want to adopt BAMT can do so directly (without any overlapping TST) or in conjunction with a period of evaluation (e.g., 1 or 2 years) during which time both TST and BAMT are used. 99 Bottles 1.0 crack serial keygen testing for BAMT would be established as a single step test. As with the TST, BAMT results should be recorded in detail. The details should include date of blood draw, result in specific units, and the laboratory interpretation (positive, negative, or indeterminate—and the concentration of cytokine measured, for example, interferon-gamma [IFN-γ]).

Risk Classification Examples

Inpatient Settings with More Than 200 Beds

If less than six TB patients for the preceding year, classify as low risk. If greater than or equal to six TB patients for the preceding year, classify as medium risk.

Inpatient Settings with Less Than 200 Beds

If less than three TB patients for the preceding year, classify as low risk. If greater than or equal to three TB patients for the preceding year, classify as medium risk.

Outpatient, Outreach, Adobe Photoshop 2021 With Crack Free Download Home-Based Health-Care Settings

If less than 99 Bottles 1.0 crack serial keygen TB patients for the preceding year, classify as low 99 Bottles 1.0 crack serial keygen. If greater than or equal to three TB patients for the preceding year, classify as medium risk.

Hypothetical Risk Classification Examples

The following hypothetical situations illustrate how assessment data are used to assign a risk classification. The risk classifications are for settings in which patients with suspected or confirmed infectious TB disease are expected to be encountered.

Example A. The setting is a 150-bed hospital located in a small city. During the preceding year, the hospital admitted two patients with a diagnosis of TB disease. One was admitted directly to an AII room, and one stayed on a medical ward for 2 days before being placed in an AII room. A contact investigation of exposed HCWs by hospital infection-control personnel in consultation with the state or local health department did not identify any health-care–associated transmission. Risk classification: low risk.

Example B. The setting is an ambulatory-care site in which a TB clinic is held 2 days per week. During the preceding year, care was delivered to six patients with TB disease and approximately 50 persons with LTBI. No instances of transmission of M. tuberculosis were noted. Risk classification: medium risk (because it is a TB clinic).

Example C. The setting is a large publicly funded hospital in a major metropolitan area. The hospital admits an average of 150 patients with TB disease each year, comprising 35% of the city burden. The setting has a strong TB infection-control AVG AntiVirus 20 Crack FREE Download (i.e., annually updates infection-control plan, 99 Bottles 1.0 crack serial keygen, fully implements infection-control plan, 99 Bottles 1.0 crack serial keygen, and has enough AII rooms [see Environmental Controls]) and an annual conversion rate (for tests for M. tuberculosis infection) among HCWs of 0.5%. No evidence of health-care–associated transmission 99 Bottles 1.0 crack serial keygen apparent. The hospital has strong collaborative linkages with the state or local health department. Risk classification: medium risk (with close ongoing surveillance for episodes of transmission from unrecognized cases of TB disease, test conversions for M. tuberculosis infection in HCWs as a result of health-care–associated transmission, and specific groups or areas in which a higher risk for health-care–associated transmission exists).

Example D. The setting is an inpatient area of a correctional facility. A proportion of the inmates were born in countries where TB disease is endemic. Two cases of TB disease were diagnosed in inmates JoJos Bizarre Adventure Bloody Stream Full crack serial keygen the preceding year. Risk classification: medium risk (Correctional facilities should be classified as at least medium risk).

Example E. A hospital located in a large city admits 35 patients with TB disease per year, uses QFT-G to measure M. tuberculosis infection, and has an overall HCW M. tuberculosis infection test conversion rate of 1.0%. However, on annual testing, three of the 20 respiratory therapists tested had QFT-G conversions, for a rate of 15%. All of the respiratory therapists who tested positive received medical evaluations, had TB disease excluded, were diagnosed with LTBI, and were offered and completed a course of treatment for LTBI. None of the respiratory therapists had known exposures to M. tuberculosis outside the hospital. The problem evaluation revealed that 1) the respiratory therapists who converted had spent part of their time in the pulmonary function laboratory where induced sputum specimens were collected, and 2) the ventilation in the laboratory was inadequate. Risk classification: potential ongoing transmission for the respiratory therapists (because of evidence of health-care–associated transmission). The rest of the setting was classified as medium risk. To address the problem, booths were installed for sputum induction. On subsequent testing for M. tuberculosis infection, no conversions were noted 99 Bottles 1.0 crack serial keygen the repeat testing 3 months later, and the respiratory therapists were then reclassified back to medium risk.

Example F. The setting is an ambulatory-care center associated with a large health maintenance organization (HMO). The patient volume is high, and 99 Bottles 1.0 crack serial keygen HMO is located in the inner city where TB rates are the highest in the state. During the preceding year, one patient who was known to have TB disease was evaluated at the center. The person was recognized as a TB patient on his first visit and was promptly triaged to an ED with an AII room capacity. While in the ambulatory-care center, the patient was held in an area separate from HCWs and other patients and instructed to wear a surgical or procedure mask, if possible. QFT-G was used for infection-control surveillance purposes, and a contact investigation was conducted among exposed staff, and no QFT-G conversions were noted. Risk classification: low risk.

Example G. The setting is a clinic for the care of persons infected with HIV. The clinic serves a large metropolitan area and a patient population of 2,000. The clinic has an AII room and a TB infection-control program, 99 Bottles 1.0 crack serial keygen. All patients are screened for TB disease upon enrollment, and airborne precautions are promptly initiated for anyone with respiratory complaints while the patient is being evaluated. During the preceding year, seven patients who were encountered in the clinic were subsequently determined to have TB disease. All patients were promptly put into an AII room, and no contact investigations were performed. The local health department was promptly notified in all cases. Annual TST has determined a conversion rate of 0.3%, 99 Bottles 1.0 crack serial keygen, which is low compared with the rate of the hospital with which the clinic is associated. Risk classification: medium risk (because persons infected with HIV might be encountered).

Example H. A home health-care agency employs 125 workers, many of whom perform duties, including nursing, physical therapy, 99 Bottles 1.0 crack serial keygen, Windows Movie Maker Registration Code 2021 With Full Crack basic home care. The agency did not care for any patients with suspected or confirmed TB disease during the preceding year. Approximately 30% of the agency's workers are foreign-born, many of whom have immigrated within the previous 5 years. At baseline two-step testing, four had a positive initial TST result, and two had a positive second-step TST result. All except one of these workers was foreign-born. Upon 99 Bottles 1.0 crack serial keygen screening, none were determined to have TB disease. The home health-care agency is based in a major metropolitan area and delivers care to a community where the majority of persons are poor and medically underserved and TB case rates are higher than the community as a whole. Risk classification: low risk (because HCWs might be from populations at higher risk for LTBI and subsequent progression to TB disease because of foreign birth and recent immigration or HIV-infected clients might be overrepresented, medium risk could be considered).

Screening HCWs Who Transfer to Other Health-Care Settings

All HCWs should receive baseline TB screening, even in settings considered to be low risk. Infection-control plans should address HCWs who transfer from one health-care setting to another and consider that the transferring HCWs might be at an equivalent or higher risk for cricket 19 in different settings. Infection-control plans might need to be customized to balance the assessed risks and the efficacy of the plan based on consideration of various logistical factors. Guidance is provided based on different scenarios.

Because some institutions might adopt BAMT for the purposes of testing for M. tuberculosis infection, infection-control programs might be confronted with interpreting historic and current TST and BAMT results when HCWs transfer to a different setting. On a case-by-case basis, expert medical opinion might be needed to interpret results and refer patients with discordant BAMT and TST baseline results. Therefore, infection-control programs should keep all records when documenting previous test results. For example, an infection-control program using a BAMT strategy should request and keep historic TST results of a HCW transferring from a previous setting. Even if the HCW is transferring from a setting that used BAMT to a setting that uses BAMT, historic TST results might be needed when in the future the HCW transfers to a setting that uses TST. Similarly, historic BAMT results might be needed Reiboot pro crack serial keygen the HCW transfers from a setting that used TST to a setting that uses BAMT.

HCWs transferring from low-risk to low-risk settings. After a baseline result for infection with M. tuberculosis is established and documented, serial testing for M. tuberculosis infection is not necessary.

HCWs transferring from low-risk to medium-risk settings. After a baseline result for infection with M. tuberculosis is established and documented, annual TB screening (including a symptom screen and TST or BAMT for persons with previously negative test results) should be performed.

HCWs transferring from low- or medium-risk settings to settings with a temporary classification of potential ongoing transmission. After a baseline result for infection with M. tuberculosis is established, a decision should be made 99 Bottles 1.0 crack serial keygen follow-up screening on an individual basis. If transmission seems to be ongoing, consider including the HCW in the screenings every 8–10 weeks until a determination has been made that ongoing transmission has ceased. When the setting is reclassified back to medium-risk, annual TB screening should be resumed.

Calculation and Use of Conversion Rates for M. tuberculosis Infection

The M. tuberculosis infection conversion rate is the percentage of HCWs whose test result for M. tuberculosis infection has converted within a specified period. Timely detection of M. tuberculosis infection in HCWs not only facilitates treatment for LTBI, but also can indicate the need for a source case investigation and a revision of the risk assessment for the setting. Conversion in test results for M. tuberculosis, regardless of the testing 99 Bottles 1.0 crack serial keygen used, is usually interpreted as presumptive evidence of new M. tuberculosis infection, and recent infections are associated with an increased risk for progression to TB disease.

For administrative purposes, a TST conversion is ≥10 mm increase in the size of the TST induration during a 2-year period in 1) an HCW with a documented negative (<10 mm) baseline two-step TST result or 2) a person who is not an HCW with a negative (<10 mm) TST result within 2 years.

In settings conducting serial testing for M. 99 Bottles 1.0 crack serial keygen infection (medium-risk settings), use the following steps to estimate the risk for test conversion in HCWs.

  • Calculate a conversion rate by dividing the number of conversions among HCWs in the setting in a specified period (numerator) by the number of HCWs who received tests in the setting over 99 Bottles 1.0 crack serial keygen same period (denominator) multiplied by 100 (see Use of Conversion Test Data for M. tuberculosis Infection To Identify Lapses in Infection Control).
  • Identify areas or groups in the setting with a potentially high risk for M. tuberculosis transmission by comparing conversion rates in HCWs with potential exposure to patients with TB disease to conversion rates in HCWs for whom health-care–associated exposure to M. tuberculosis is not probable.

Use of Conversion Test Data for M. tuberculosis Infection To Identify Lapses in Infection Control

  • Conversion rates above the baseline level (which will be different in each setting) should instigate an investigation to evaluate the likelihood of health-care–associated transmission. When testing for M. tuberculosis infection, if conversions are determined to be the result of well-documented community exposure or probable false-positive test results, then the risk classification of the setting does not need to be adjusted.
  • For settings that no longer perform serial testing for M. tuberculosis infection among HCWs, reassessment of the risk for the setting is essential to ensure that the infection-control program is effective. The setting should have ongoing communication with the local or state health department regarding incidence and epidemiology of TB in the population served and should ensure that timely contact investigations are performed for HCWs or patients with unprotected exposure to a person with TB disease.

Example Calculation of Conversion Rates

Medical Center A is classified as medium risk and uses TST for annual screening. At the end of 2004, a total of 10,051 persons were designated as HCWs. Of these, 9,246 had negative baseline test results for M. tuberculosis infection. Of the HCWs tested, 99 Bottles 1.0 crack serial keygen, 10 experienced an increase in TST result by ≥10 mm, 99 Bottles 1.0 crack serial keygen. The overall setting conversion rate for 2004 is 0.11%. If five of the 10 HCWs whose test results converted were among the 100 HCWs employed in the ICU of Hospital X (in Medical Center A), then the ICU setting-specific conversion rate for 2004 is 5%.

Evaluation of HCWs for LTBI should include information from a serial testing program, but this information must be interpreted as only one part of a full assessment. TST or BAMT conversion criteria for administrative (surveillance) purposes are not applicable for medical evaluation of HCWs for the diagnosis of LTBI (see Supplement, 99 Bottles 1.0 crack serial keygen, Surveillance and Detection of M. tuberculosis Infections in Health-Care Workers [HCWs]).

Evaluation of TB Infection-Control Procedures and Identification of Problems

Annual evaluations of the TB infection-control plan are needed to ensure the proper implementation of the plan and to recognize and correct lapses in infection control. Previous hospital admissions and outpatient visits of patients with TB disease should be noted before the onset of TB symptoms. Medical records of a sample of patients with suspected and confirmed TB disease who were treated or examined at the setting should be reviewed to identify possible problems in TB infection control. The review should be based on the factors listed on the TB Risk Assessment Worksheet (Appendix B).

  • Time interval from suspicion of TB until initiation of airborne precautions and antituberculosis treatment to:
    — suspicion of TB disease and patient triage to proper AII room or referral center for settings that do not provide care for patients with suspected or confirmed TB disease;
    — admission until TB disease was suspected;
    — admission until medical evaluation for TB disease was performed;
    — admission until specimens for AFB smears and polymerase chain reaction (PCR)–based nucleic acid amplification (NAA) tests for M, 99 Bottles 1.0 crack serial keygen. tuberculosis were ordered;
    — admission until specimens for mycobacterial culture were ordered;
    — ordering of AFB smears, NAA tests, and mycobacterial culture until specimens were collected;
    — collection of specimens until performance and AFB smear results were reported;
    — collection of specimens until performance and culture results were reported;
    — collection of specimens until species identification was reported;
    — collection of specimens until drug-susceptibility test results were reported;
    — admission until airborne precautions were initiated; and
    — admission until antituberculosis treatment was initiated.
  • Duration of airborne precautions.
  • Measurement of meeting criteria for discontinuing airborne precautions. Certain patients might be correctly discharged from an AII room to home.
  • Patient history of previous admission.
  • Adequacy of antituberculosis treatment regimens.
  • Adequacy of procedures for collection of follow-up sputum specimens.
  • Adequacy of discharge planning.
  • Number of visits to outpatient setting from the start of symptoms until TB disease was suspected (for outpatient settings).

Work practices related to airborne precautions should be observed to determine if employers are enforcing all practices, if HCWs are adhering to infection-control policies, and if patient adherence to airborne precautions is being enforced. Data from the case reviews and observations in the annual risk assessment should be used to determine the need to modify 1) protocols for identifying and initiating prompt airborne precautions for patients with suspected or confirmed infectious TB disease, 2) protocols for patient management, 3) laboratory procedures, or 4) TB training and education programs for HCWs.

Environmental Assessment

  • Data from the most recent environmental evaluation should be reviewed to determine if recommended environmental controls are in place (see Suggested Components of an Initial TB Training and Education Program for HCWs).
  • Environmental control maintenance procedures and logs should be reviewed to determine if maintenance is conducted properly and regularly.
  • Environmental control design specifications should be compared with guidelines from the American Institute of Architects (AIA) and other ventilation guidelines (117,118) (see Risk Classification Examples) and the installed system performance.
  • Environmental data should be used to assist building managers and engineers in evaluating the performance of the installed system.
  • The number and types of aerosol-generating or aerosol-producing procedures (e.g., 99 Bottles 1.0 crack serial keygen, specimen processing and manipulation, bronchoscopy, sputum induction, and administration of aerosolized medications) performed in the setting should be assessed.
  • The number of AII rooms should be suitable for the setting based on AIA Guidelines and the setting risk assessment. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has adapted the AIA guidelines when accrediting facilities (118).

Suggested Components of an Initial TB Training and Education Program for HCWs

The following are suggested components of an initial TB training and education program:

1. Clinical Information

Basic concepts of M. tuberculosis transmission, pathogenesis, and diagnosis, including the difference between LTBI and TB disease and the possibility of reinfection after previous infection with M. tuberculosis or TB disease.

  • Symptoms and signs of TB disease and the importance of a high index of suspicion for patients or HCWs with these symptoms.
  • Indications for initiation of airborne precautions of inpatients with suspected or confirmed TB disease.
  • Policies and indications for GoldWave v3.03 for Windows crack serial keygen airborne precautions.
  • Principles of treatment for LTBI and for TB disease (indications, use, effectiveness, and potential adverse effects).

2. Epidemiology of TB

  • Epidemiology of TB in the local community, the United States, and worldwide.
  • Risk factors for TB disease.

3. Infection-Control Practices to Prevent and Detect M. tuberculosis Transmission in Health-Care Settings

  • Overview of the TB infection-control program.
  • Potential for occupational exposure to infectious TB disease in health-care settings.
  • Principles and practices of infection control to reduce the risk for transmission of M, 99 Bottles 1.0 crack serial keygen. tuberculosis, including the hierarchy of TB infection-control measures, written policies and procedures, monitoring, and control measures for HCWs at increased risk for exposure to M. tuberculosis.
  • Rationale for infection-control measures and documentation evaluating the effect of these measures in reducing occupational TB risk exposure and M. tuberculosis transmission.
  • Reasons for testing for M. tuberculosis infection, importance of a positive test result for M. tuberculosis infection, importance of participation in a TB screening program, and importance of retaining documentation of previous test result for M. tuberculosis infection, chest radiograph results, and treatment for LTBI and TB disease.
  • Efficacy and safety of BCG vaccination and principles of screening for M. tuberculosis infection and interpretation in BCG recipients.
  • Procedures for investigating an M. tuberculosis infection test conversion or TB disease occurring in the workplace.
  • Joint responsibility of HCWs and employers to ensure prompt medical evaluation after M. tuberculosis test conversion or development of symptoms or signs 99 Bottles 1.0 crack serial keygen TB disease in HCWs.
  • Role of HCW in preventing transmission of M. tuberculosis.
  • Responsibility of HCWs to promptly report a diagnosis of TB disease to the setting's administration and infection-control program.
  • Responsibility of clinicians and the infection-control program to report to the state or local health department a suspected case of TB disease in a patient (including autopsy findings) or HCW.
  • Responsibilities and policies of the setting, the local health department, and the state health department to ensure confidentiality for HCWs with TB disease or LTBI.
  • Responsibility of the setting to inform EMS staff who transported a patient with suspected or confirmed TB disease.
  • Responsibilities and policies of the setting to ensure that an HCW with TB disease is noninfectious before returning to duty.
  • Importance of completing therapy for LTBI or TB disease to protect the HCW's health and to reduce the risk to others.
  • Proper implementation and monitoring of environmental controls (see Environmental Controls).
  • Training for safe collection, management, and disposal of clinical specimens.
  • Required Occupational Safety and Health Administration (OSHA) record keeping on HCW test conversions for M. tuberculosis infection.
  • Record-keeping and surveillance of TB cases among patients in the setting.
  • Proper use of (see Respiratory Protection) and the need to inform the infection-control program of factors that might affect the efficacy of respiratory protection as required by OSHA.
  • Success of adherence to infection-control practices in decreasing the risk for transmission of M. tuberculosis in health-care settings.

4. TB and Immunocompromising Conditions

  • Relationship between infection with M. tuberculosis and medical conditions and treatments that can lead to impaired immunity.
  • 99 Bottles 1.0 crack serial keygen tests and counseling and referrals for persons with HIV infection, diabetes, and other immunocompromising conditions associated with an increased risk for progression to TB disease.
  • Procedures for informing employee health or infection-control personnel of medical conditions associated with immunosuppression.
  • Policies on voluntary work reassignment options for immunocompromised HCWs.
  • Applicable confidentiality safeguards of the health-care setting, locality, and state.

5. TB and Public Health

  • Role of the local and state health department's TB-control program in screening for LTBI and TB disease, providing treatment, conducting contact investigations and outbreak investigations, and providing education, counseling, and responses to public inquiries.
  • Roles of CDC and of OSHA.
  • Availability of information, advice, and counseling from community sources, including universities, local experts, and hotlines.
  • Responsibility of the setting's clinicians and infection-control program to promptly report to the state or local health department a case of suspected TB disease or a cluster of TST or BAMT conversions.
  • Responsibility of the setting's clinicians and infection-control program to promptly report to the state or local health department a person with suspected or confirmed TB disease who leaves the setting against medical advice.

Managing Patients Who Have Suspected or Confirmed TB Disease: General Recommendations

The primary TB risk to HCWs is the undiagnosed or unsuspected patient with infectious TB disease. A high index of suspicion for TB disease and rapid implementation of precautions are essential to prevent and interrupt transmission. Specific precautions will vary depending on the setting.

Prompt Triage

Within health-care settings, protocols should be implemented and enforced to promptly identify, separate from others, and either transfer or manage persons who have suspected or confirmed infectious TB disease. When patients' medical histories are taken, 99 Bottles 1.0 crack serial keygen, all patients should be routinely asked about 1) a history of TB exposure, infection, or disease; 2) symptoms or signs of TB disease; and 3) medical conditions that increase their risk for TB disease (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease). The medical evaluation should include an interview conducted in the patient's primary language, with the assistance of a qualified medical interpreter, if necessary. HCWs who are the first point of contact should be trained to ask questions that will facilitate detection of persons who have suspected or confirmed infectious TB disease. For assistance with language interpretation, contact the local and state health department. Interpretation resources are also available (119) at http://www.atanet.org; http://www.languageline.com; and http://www.ncihc.org.

A 99 Bottles 1.0 crack serial keygen of respiratory TB disease should be considered for any patient with symptoms or signs of infection in the lung, pleura, or airways (including larynx), including coughing for ≥3 weeks, loss of appetite, unexplained weight loss, night sweats, 99 Bottles 1.0 crack serial keygen, bloody sputum or hemoptysis, hoarseness, fever, fatigue, or chest pain. The index of suspicion for TB disease will Express VPN 10.3.0.23 Crack With Activation Code (2021) by geographic area and will depend on the population served by the setting. The index of suspicion should be substantially high for geographic areas and groups of patients characterized by high TB incidence (26).

Special steps should be taken in settings other than TB clinics. Patients with symptoms suggestive of undiagnosed or inadequately treated TB disease should be promptly referred so that they can receive a medical evaluation. These patients should not be kept in the setting any longer than required to arrange a referral or transfer to an AII room. While in the setting, symptomatic patients should wear a surgical or procedure mask, if possible, and should be instructed to observe strict respiratory hygiene and cough etiquette procedures (see Glossary) (120–122).

Immunocompromised persons, including those who are HIV-infected, with infectious TB disease should be physically separated from other persons to protect both themselves and others. To avoid exposing HIV-infected or otherwise severely immunocompromised persons to M. tuberculosis, consider location and scheduling issues to avoid exposure.

TB Airborne Precautions

Within health-care settings, TB airborne precautions should be initiated for any patient who has symptoms or signs of TB disease, or who has documented infectious TB disease and has not completed antituberculosis treatment. For patients placed in AII rooms because of suspected infectious TB disease of the lungs, airway, or larynx, airborne precautions may be discontinued when infectious TB disease is considered unlikely and either 1) another diagnosis is made that explains the clinical syndrome or 2) the patient has three consecutive, negative AFB sputum smear results (109–112,123). Each of the three sputum specimens should be collected in 8–24-hour intervals (124), and at least one specimen should be an early morning specimen because respiratory secretions pool overnight. Generally, 99 Bottles 1.0 crack serial keygen method will allow patients with negative sputum smear results to be released from airborne precautions in 2 days.

The classification of the risk assessment of the health-care setting is used to determine how many AII rooms each setting needs, 99 Bottles 1.0 crack serial keygen, depending on the number of TB patients examined. At least one AII room is needed for settings in which TB patients stay while they are being treated, and additional AII rooms might be needed depending on the magnitude of patient-days of persons with suspected or confirmed TB disease (118). Additional rooms might be considered if options are limited for transferring patients with suspected or confirmed TB disease to other settings with AII rooms. For example, for a hospital with 120 beds, a minimum of one AII room is needed, possibly more, depending on how many TB patients are examined in 1 year.

TB Airborne Precautions for Settings in Which Patients with Suspected or Confirmed TB Disease Are Expected To Be Encountered

Settings that plan to evaluate and manage patients with TB disease should have at least one AII room or enclosure that 99 Bottles 1.0 crack serial keygen AII requirements (see Environmental Controls; and Supplement, Environmental Controls). These settings should develop written policies that specify 1) indications for airborne precautions, 2) persons authorized to initiate and discontinue airborne precautions, 3) specific airborne precautions, 4) AII room-monitoring procedures, 5) procedures for managing patients who do not adhere to airborne precautions, and 6) criteria for discontinuing airborne precautions.

A high index of suspicion should be maintained for TB disease. If a patient has suspected or confirmed TB disease, airborne precautions should be promptly initiated. Persons with suspected or confirmed TB disease who are inpatients should remain in AII rooms until they are determined to be noninfectious and have demonstrated a clinical response to a standard multidrug antituberculosis treatment regimen or until an alternative diagnosis is made. If the alternative diagnosis cannot be clearly established, even with three negative sputum smear results, empiric treatment of TB disease should strongly be considered (see Supplement, Estimating the Infectiousness of a TB Patient). Outpatients with suspected or confirmed infectious TB disease should remain in AII rooms until they are transferred or until their visit is complete.

TB Airborne Precautions for Settings in Which Patients with Suspected or Confirmed TB Disease Are Not Expected To Be Encountered

Settings in which patients with suspected or confirmed TB disease are not expected to be encountered do not need an AII room or a respiratory-protection program for the prevention of transmission of M. tuberculosis. However, follow these steps in these settings.

A written protocol should be developed for referring patients with suspected or confirmed TB disease to a collaborating referral setting in which the patient can be evaluated and managed properly. The referral setting should provide documentation of intent to collaborate. The protocol should be reviewed routinely and revised as needed.

Patients with suspected or confirmed TB disease should be placed in an AII room, if available, or in a room that meets the requirements for an AII room, or in a separate room with the door closed, apart from other patients and not in an open waiting area. Adequate time should elapse to ensure removal of M. tuberculosis–contaminated room air before allowing entry by staff or another patient (Tables 1 and 2).

If an AII room is not available, persons with suspected or confirmed infectious TB disease should wear a surgical or procedure mask, if possible. Patients should be instructed to keep the mask on and to change the mask if it becomes wet. If patients cannot tolerate a mask, they should observe strict respiratory hygiene and cough etiquette procedures.

AII Room Practices

AII rooms should be single-patient rooms in which environmental factors and entry of visitors and HCWs are controlled to minimize the transmission of M. tuberculosis. All HCWs who enter an AII room should wear at least N95 disposable respirators (see Respiratory Protection). Visitors may be offered respiratory protection (i.e., N95) and should be instructed by HCWs on the use of the respirator before 99 Bottles 1.0 crack serial keygen an AII room. AII rooms have specific requirements for controlled ventilation, negative pressure, and air filtration (118) (see Environmental Controls). Each inpatient AII room should have a private bathroom.

Settings with AII Rooms

Health-care personnel settings with AII rooms should

  • keep doors to AII rooms closed except when patients, HCWs, or others must enter or exit 99 Bottles 1.0 crack serial keygen room (118);
  • maintain enough AII rooms to provide airborne precautions of all patients who have suspected or 99 Bottles 1.0 crack serial keygen TB disease. Estimate the number of AII rooms needed based on the results of the risk assessment for the setting;
  • monitor and record direction of airflow (i.e., negative pressure) in the room on a daily basis, while the room is being used for TB airborne precautions. Record results in an electronic or readily retrievable document;
  • consider grouping AII rooms in one part of the health-care setting to limit costs, 99 Bottles 1.0 crack serial keygen, reduce the possibility of transmitting M. tuberculosis to other patients, facilitate the care of TB patients, and facilitate the installation and maintenance of optimal environmental controls (particularly ventilation). Depending on the architecture and the environmental control systems of a particular setting, AII rooms might be grouped either horizontally (e.g., a wing of a facility) or vertically (e.g., the last few rooms edius pro 9.55 X32 bit free dow Archives separate floors of a 99 Bottles 1.0 crack serial keygen perform diagnostic and treatment procedures (e.g., sputum collection and inhalation therapy) in an AII room.
  • ensure patient adherence to airborne precautions. In their primary language, with the assistance of a qualified medical interpreter, if necessary, educate patients (and family and visitors) who are placed in an AII room about M. tuberculosis transmission and the reasons for airborne precautions. For assistance with language interpretation, contact the local and state health department. Interpretation resources are available (119) at http://www.atanet.org; http://www.languageline.com; and http://www.ncihc.org. Facilitate patient adherence by using incentives (e.g., provide telephones, televisions, or radios in AII rooms; and grant special dietary requests) and other measures. Address problems that could interfere with adherence (e.g., management of withdrawal from addictive substances, including tobacco); and
  • ensure that patients with suspected or confirmed infectious TB disease who must be transported to another area of the setting or to another setting for a medically essential procedure bypass the waiting area and wear a surgical or procedure mask, if possible. Drivers, HCWs, and other staff who are transporting persons with suspected or confirmed infectious TB disease might consider wearing an N95 respirator. Schedule procedures on patients with TB disease when a minimum number of HCWs and other patients are present and as the last procedure of the day to maximize the time available for removal of airborne contamination (Tables 1 and 2).

Diagnostic Procedures

Diagnostic procedures should be performed in settings with appropriate infection-control capabilities. The following recommendations should be applied for diagnosing TB disease and for evaluating patients for potential infectiousness.

Clinical Diagnosis

A complete medical history should be obtained, including symptoms of TB disease, previous TB disease and treatment, previous history of infection with M. tuberculosis, and previous treatment of LTBI or exposure to persons with TB disease. A physical examination should be performed, including chest radiograph, microscopic examination, culture, and, when indicated, NAA testing of sputum (39,53,125,126). If possible, sputum induction with aerosol inhalation is preferred, particularly when the patient cannot produce sputum. Gastric aspiration might be necessary for those patients, particularly children, who cannot produce sputum, even with aerosol inhalation (127–130). Bronchoscopy might be needed for specimen collection, especially if sputum specimens have been nondiagnostic and doubt exists as to the diagnosis (90,111,127,128,131–134).

All patients with suspected or confirmed infectious TB disease should be placed under airborne precautions until they have been determined to be noninfectious (see Supplement, Estimating the Infectiousness of a TB Patient). Adult and adolescent patients who might be infectious include persons who are coughing; have cavitation on chest radiograph; have positive AFB sputum smear results; have respiratory tract disease with involvement of the lung, pleura or airways, including larynx, 99 Bottles 1.0 crack serial keygen fail to cover the mouth and nose when coughing; are not on antituberculosis treatment or are on incorrect antituberculosis treatment; or are undergoing cough-inducing or aerosol-generating procedures (e.g., sputum induction, bronchoscopy, and airway suction) (30,135).

Persons diagnosed with extrapulmonary TB disease should be evaluated for the presence of concurrent pulmonary TB disease. An additional concern in infection control with children relates to adult household members and visitors who might be the source case (136). Pediatric patients, including adolescents, who might be infectious include those who have extensive pulmonary or laryngeal involvement, prolonged cough, positive sputum AFB smears results, cavitary TB on chest radiograph (as is typically observed in immunocompetent adults with TB disease), or those for whom cough-inducing or aerosol-generating procedures are performed (136,137).

Although children are uncommonly infectious, pediatric patients should be evaluated for infectiousness by using the same criteria as for adults (i.e., on the basis of pulmonary or laryngeal involvement). Patients with suspected or confirmed TB disease should be immediately reported to the local public health authorities so that arrangements can be made for tracking their treatment to completion, preferably through a case management system, so that DOT can be arranged and standard procedures for identifying and evaluating TB contacts can be initiated. Coordinate efforts with the local or state health department to arrange treatment and long-term follow-up and evaluation of contacts.

Laboratory Diagnosis

To produce the highest quality laboratory results, laboratories performing mycobacteriologic tests should be skilled in both the laboratory and the administrative aspects of specimen processing. Laboratories should use or have prompt access to the most rapid methods available: 1) fluorescent microscopy and concentration for AFB smears; 2) rapid NAA testing for direct detection of M. tuberculosis in patient specimens (125); 3) solid and rapid broth culture methods for isolation of mycobacteria; 4) nucleic acid probes or high pressure liquid chromatography (HPLC) for species identification; and 5) rapid broth culture methods for drug susceptibility testing. Laboratories should incorporate other more rapid or sensitive tests as they become available, practical, and affordable (see Supplement, Diagnostic Procedures for LTBI and TB Disease) (138,139).

In accordance with local and state laws and regulations, a system should be in place to ensure that laboratories report any positive results from any specimens to clinicians within 24 hours of receipt of the specimen (139,140). Certain settings perform AFB smears on-site for rapid results (and results should be reported to clinicians within 24 hours) and then send specimens or cultures to a referral laboratory for identification and drug-susceptibility testing. This referral practice can speed the receipt of smear results but delay culture identification and drug-susceptibility results. Settings that cannot provide the full range of mycobacteriologic testing services should contract with their referral laboratories to ensure rapid results while maintaining proficiency for on-site testing. In addition, referral laboratories should be instructed to store isolates in case additional testing is necessary.

All drug susceptibility results on M. tuberculosis isolates should be reported to the local or state health department as soon as these results are available. Laboratories that rarely receive specimens for mycobacteriologic analysis should refer specimens to a laboratory that performs these tests routinely. The reference laboratory should provide rapid testing and reporting. Out-of-state reference laboratories should provide all results to the local or state health department from which the specimen originated.

Special Considerations for Persons Who Are at High Risk for TB Disease or in Whom TB Disease Might Be Difficult to Diagnose

The probability of TB disease is higher among patients who 1) previously had TB 99 Bottles 1.0 crack serial keygen or were exposed to M. tuberculosis, 99 Bottles 1.0 crack serial keygen, 2) belong to a group at high risk for TB disease or, 3) have a positive TST or BAMT result. TB disease is strongly suggested if the diagnostic evaluation Euro Truck Simulator 2 Crack 1.37 Torrent Archives symptoms or signs of TB disease, a chest radiograph consistent with TB disease, or AFB in sputum or from any other Driver Booster 8 PRO crack serial keygen. TB disease can occur simultaneously in immunocompromised persons who have pulmonary infections caused by other organisms (e.g., Pneumocystis jaroveci [formerly P. carinii] and M. avium complex) and should be considered in the diagnostic evaluation of all such patients with symptoms or signs of TB disease (53).

TB disease can be difficult to diagnose in persons who have HIV infection (49) (or other conditions associated with severe suppression of cell mediated immunity) because 99 Bottles 1.0 crack serial keygen nonclassical or normal radiographic presentation or the simultaneous occurrence of other pulmonary infections (e.g., P. jaroveci or M. avium complex) (2). Patients who are HIV-infected are also at greater risk for having extrapulmonary TB (2). The difficulty in diagnosing TB disease in HIV-infected can be compounded by the possible lower sensitivity and specificity of sputum smear results for detecting AFB (53,141) and the overgrowth of cultures with M. avium complex in specimens from patients infected with both M, 99 Bottles 1.0 crack serial keygen. tuberculosis and M. avium complex. The TST in patients with advanced HIV infection is unreliable and cannot be used in clinical decision making (35,53,142).

For immunocompromised patients who have respiratory symptoms or signs that are attributed initially to infections or conditions other 99 Bottles 1.0 crack serial keygen TB disease, conduct an evaluation for coexisting TB disease. If the patient does not respond to recommended treatment for the presumed cause of the pulmonary abnormalities, repeat the evaluation (see Supplement, Diagnostic Procedures for LTBI and TB Disease). In certain settings in which immunocompromised patients and patients with TB disease are examined, implementing airborne precautions might be prudent for all persons at high risk. These persons include those infected with HIV who have an abnormal chest radiograph or respiratory symptoms, symptomatic foreign-born persons who have immigrated within the previous 5 years from TB-endemic countries, and persons with pulmonary infiltrates on chest radiograph, or symptoms or signs of TB disease.

Initiation of Treatment

For patients who have confirmed TB disease or who are considered highly probable to have TB disease, promptly start antituberculosis treatment in accordance with current guidelines (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease) (31). In accordance with local and state regulations, local health departments should be notified of all cases of suspected TB.

DOT is the standard of care for all patients with TB disease and should be used for all doses during the course of therapy for treatment of TB disease. All inpatient medication should be administered by DOT and reported to the state or local health department. Rates of relapse and development of drug-resistance are decreased when DOT is used (143–145). All patients on intermittent (i.e., once or twice per week) treatment for TB disease or LTBI should receive DOT. Settings should collaborate with the local or state health department on decisions concerning inpatient DOT and arrangements for outpatient DOT (31).

Managing Patients Who Have Suspected or Confirmed TB Disease: Considerations for Special Circumstances and Settings

The recommendations for preventing transmission of M. tuberculosis are applicable to all health-care settings, including those that have been described (Appendix A). These settings should each have independent risk assessments if they are stand-alone settings, or each setting should have a detailed section written as part of the risk assessment for the overall setting.

Minimum Requirements

The specific precautions for the settings included in this section vary, depending on the setting.

Inpatient Settings

Emergency Departments (EDs)

The symptoms of TB disease are usually symptoms for which patients might seek treatment in EDs. Because TB symptoms are common and 99 Bottles 1.0 crack serial keygen, infectious TB disease could be encountered in these settings. The use of ED-based TB screening has not been demonstrated to be consistently effective (146).

The amount of time patients with suspected or confirmed infectious TB disease spend in EDs and urgent-care settings should be minimized. Patients with suspected or confirmed infectious TB disease should be promptly identified, 99 Bottles 1.0 crack serial keygen, evaluated, and separated from other patients. Ideally, such patients should be placed in an AII room. When an AII room is not available, use a room with effective general ventilation, and use air cleaning technologies (e.g., a portable HEPA filtration system), if available, or transfer the patient to a setting or area with recommended infection-control capacity. Facility engineering personnel with expertise in heating, ventilation, and air conditioning (HVAC) and air handlers have evaluated how this option is applied to ensure no over pressurization of return air or unwanted deviations exists in design of air flow in the zone.

EDs with a high volume of patients with suspected or confirmed TB disease should have at least one AII room (see TB Risk Assessment). Air-cleaning technologies (e.g., 99 Bottles 1.0 crack serial keygen, HEPA filtration and UVGI) can be used to increase equivalent air changes per hour (ACH) in waiting areas (Table 1). HCWs entering an AII room or any room with a patient with infectious TB disease should wear at least an N95 disposable respirator. After a patient with suspected or confirmed TB disease exits a room, allow adequate time to elapse to ensure removal of M. tuberculosis-contaminated room air before allowing entry by staff or another patient (Tables 1 and 2).

Before a patient leaves an AII room, perform an assessment of 1) the patient's need to discontinue airborne precautions, 2) the risk for transmission and the patient's ability 99 Bottles 1.0 crack serial keygen observe strict respiratory hygiene, and 3) cough etiquette procedures. Patients with suspected or confirmed infectious TB who are outside an AII room should wear a surgical or procedure mask, if possible, 99 Bottles 1.0 crack serial keygen. Patients who cannot tolerate masks because of medical conditions should observe strict respiratory hygiene and cough etiquette procedures.

Intensive Care Units (ICUs)

Patients with infectious TB disease might become sick enough to require admission to an ICU. Place ICU patients with suspected or confirmed infectious TB disease in an AII room, if possible. ICUs with a high volume of patients with suspected or confirmed TB disease should have at CCleaner Key 5.73 Crack Free Download Latest [Full Version] one AII room (Appendix B). Air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase equivalent ACH in waiting areas (see Environmental Controls).

HCWs entering an AII room or any room with a patient with infectious TB disease should wear at least an N95 disposable respirator, 99 Bottles 1.0 crack serial keygen. To help reduce the risk for contaminating a ventilator or discharging M. tuberculosis into the ambient air when mechanically ventilating (i.e., with a ventilator or manual resuscitator) a patient with suspected or confirmed TB disease, place a bacterial filter on the patient's endotracheal tube (or at the expiratory side of the breathing circuit of a ventilator) (147–151). In selecting a bacterial filter, give preference to models specified by the manufacturer to filter particles 0.3 µm in size in both the unloaded and loaded states with a filter efficiency of ≥95% (i.e., filter penetration of <5%) at the maximum design flow rates of the ventilator for the service life of the filter, as specified by the manufacturer.

Surgical Suites

Surgical suites require special infection-control considerations for preventing transmission of M. tuberculosis. Normally, the direction of airflow should MP E District Portal – mpedistrict.gov.in CSC Registration, Certificates from the operating room (OR) to the hallway (positive pressure) to minimize contamination of the surgical field. Certain hospitals have procedure rooms with reversible airflow or pressure, whereas others have positive-pressure rooms with a negative pressure anteroom. Surgical staff, particularly those close to the surgical field, should use respiratory protection (e.g., a valveless N95 disposable respirator) to protect themselves and the patient undergoing surgery.

When possible, postpone non-urgent surgical procedures on patients with suspected or confirmed TB disease until the patient is determined to be noninfectious or determined to not have TB disease. When surgery cannot be postponed, procedures should be performed in a surgical suite with recommended ventilation controls. Procedures should be scheduled for patients with suspected or confirmed TB disease when a minimum number of HCWs and other patients are present in the surgical suite, and at the end of the day to maximize the time available for removal of airborne contamination (Tables 1 and 2).

If a surgical suite or an OR has an anteroom, the anteroom should be either 1) positive pressure compared with both the corridor and the suite or OR (with filtered supply air) or 2) negative pressure compared with both the corridor and the suite or OR. In the usual design in which an OR has no anteroom, keep the doors to the OR closed, and minimize traffic into and out of the room and in the corridor. Using additional air-cleaning technologies (e.g., UVGI) should be considered to increase the equivalent ACH. Air-cleaning systems can be placed in the room or in surrounding areas to minimize contamination of the surroundings after the procedure (114) (see Environmental Controls).

Ventilation in the OR should be designed to provide a sterile environment in the surgical field while preventing contaminated air from flowing to other areas in the health-care setting. Personnel steps should be taken to reduce the risk for contaminating ventilator or anesthesia equipment or discharging tubercle bacilli into the ambient air when operating on a patient with suspected or confirmed TB disease (152). A bacterial filter should be placed on the patient's endotracheal tube (or at the expiratory side of the breathing circuit of a ventilator or anesthesia machine, if used) (147–151). When selecting a bacterial filter, give preference to models specified by the manufacturer to filter particles 0.3 µm in size in both the unloaded and loaded states with a filter efficiency of ≥95% (i.e., filter penetration of <5%) at the maximum design flow rates of the ventilator for the service life of the filter, as specified by the manufacturer.

When surgical procedures (or other procedures that require a sterile field) are performed on patients with suspected or confirmed infectious TB, respiratory protection should be worn by HCWs to protect the sterile field from the respiratory secretions of HCWs and to protect HCWs from the infectious droplet nuclei generated from the patient. When selecting respiratory protection, do not use valved or positive-pressure respirators, because they do not protect the sterile field. A respirator with a valveless filtering facepiece (e.g., N95 disposable respirator) should be used.

Postoperative recovery of a patient with suspected or confirmed TB disease should be in an AII room in any location where the patient is recovering (118). If an AII or comparable room is not available for surgery or postoperative recovery, air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase the number of equivalent ACH (see Environmental Controls); however, the infection-control committee should be involved in the selection and placement of these supplemental controls.

Laboratories

Staff who 99 Bottles 1.0 crack serial keygen in laboratories that handle clinical specimens encounter risks not typically present in other areas of a health-care setting (153–155). Laboratories that handle TB specimens include 1) pass-through facilities that forward specimens to reference laboratories for analysis; 2) diagnostic laboratories that process specimens and perform acid-fast staining and primary culture for M. tuberculosis; and 3) facilities that perform extensive identification, subtyping, and susceptibility studies.

Procedures involving the manipulation of specimens or cultures containing M. tuberculosis introduce additional substantial risks that must be addressed in an effective TB infection-control program. Personnel who work with mycobacteriology specimens should be thoroughly trained in methods that minimize the production of aerosols and undergo periodic competency testing to include direct observation of their work practices. Risks for transmission of M. tuberculosis in laboratories include aerosol formation during any specimen or isolate manipulation and percutaneous inoculation from accidental exposures, 99 Bottles 1.0 crack serial keygen. Biosafety recommendations for laboratories performing diagnostic testing for TB have been published (74,75,138,156,157).

In laboratories affiliated with a health-care setting (e.g., a hospital) and in free-standing laboratories, the laboratory director, in collaboration with the infection-control staff for the 99 Bottles 1.0 crack serial keygen, and in ProtonVPN 2.8.96.0 With Crack Free Download [Latest] with the state TB laboratory, should develop a risk-based infection-control plan for the laboratory that minimizes the risk for exposure to M. tuberculosis. Consider factors including 1) incidence of TB disease (including drug-resistant TB) in the community and in patients served by settings that submit specimens to the laboratory, 2) design of the laboratory, 3) level of TB diagnostic service offered, 4) number of specimens processed, and 5) whether or not aerosol-generating or aerosol-producing procedures are performed and the frequency at which they are performed. Referral laboratories should store isolates in case additional testing is necessary.

Biosafety level (BSL)-2 practices and procedures, containment equipment, and facilities are required for nonaerosol-producing manipulations of clinical specimens (e.g., preparing direct smears for acid-fast staining when done in conjunction with training and periodic checking of competency) (138). All specimens suspected of containing M. tuberculosis (including specimens processed for other microorganisms) should be handled in a Class I or II biological safety cabinet (BSC) (158,159). Conduct all aerosol-generating activities (e.g., inoculating culture media, setting up biochemical and antimicrobic susceptibility tests, opening centrifuge cups, and performing sonication) in a Class I or II BSC (158).

For laboratories that are considered at least medium risk (Appendix C), conduct testing for M. tuberculosis infection at least annually among laboratorians who perform TB diagnostics or manipulate specimens from which M. tuberculosis is commonly isolated (e.g., sputum, lower respiratory secretions, or tissues) (Appendix D). More frequent testing for M. tuberculosis is recommended in the event of a documented conversion among laboratory staff or a laboratory accident that poses a risk for exposure to M. tuberculosis (e.g., malfunction of a centrifuge leading to aerosolization of a sample).

Based on the risk assessment for the laboratory, employees should use personal protective equipment (including respiratory protection) recommended by local regulations for each activity. For activities that have a low risk for generating aerosols, standard personal protective equipment consists of protective laboratory coats, gowns, or smocks designed specifically for use in the laboratory. Protective garments should be left in the laboratory before going to nonlaboratory areas.

For all laboratory procedures, disposable gloves should be worn. Gloves should be disposed of when work is completed, the gloves are overtly contaminated, or the integrity of the glove is compromised. Local or state regulations should determine procedures for the disposal of gloves. Face protection (e.g., goggles, full-facepiece respirator, face shield, or other splatter guard) should also be used when manipulating specimens inside or outside a BSC. Use respiratory protection when performing procedures that can result in aerosolization outside a BSC. The minimum level of respiratory protection is an N95 filtering facepiece respirator. Laboratory workers who use respiratory protection should be provided with the same training on respirator use and care and the same fit testing as other HCWs.

After documented laboratory accidents, conduct an investigation of exposed laboratory workers. Laboratories in which specimens for mycobacteriologic studies (e.g., AFB smears and cultures) are processed should follow the AIA and CDC/National Institute of Health guidelines (118,159) (see Environmental Controls). BSL-3 practices, containment equipment, and facilities are recommended for the propagation and manipulation of cultures of M. tuberculosis complex (including M. bovis) and for animal studies in which primates that are experimentally or naturally infected with M. tuberculosis or M. bovis are used. Animal studies in which guinea pigs or mice are used can be conducted at animal BSL-2. Aerosol infection methods are recommended to be conducted at BSL-3 (159).

Bronchoscopy Suites

Because bronchoscopy is a cough-inducing procedure that might be performed on patients with suspected or confirmed TB disease, bronchoscopy suites require special attention (29,81,160,161). Bronchoscopy can result in the transmission of M. tuberculosis either through the airborne route (29,63,81,86,162) or a contaminated bronchoscope (80,82,163–170). Closed and effectively filtered ventilatory circuitry and minimizing opening of such circuitry in intubated and mechanically ventilated patients might minimize exposure (see Intensive Care Units) (149).

If possible, avoid bronchoscopy on patients with suspected or confirmed TB disease or postpone the procedure until the patient is determined to be noninfectious, by confirmation of the three negative AFB sputum smear results (109–112). When collection of spontaneous sputum specimen is not adequate or possible, sputum induction has been demonstrated to be equivalent to bronchoscopy for obtaining specimens for culture (110). Bronchoscopy might have the advantage of confirmation of the diagnosis with histologic specimens, collection of additional specimens, 99 Bottles 1.0 crack serial keygen post bronchoscopy sputum that might increase the diagnostic yield, and the opportunity to confirm an alternate diagnosis. If the diagnosis of TB disease is suspected, consideration should be given to empiric antituberculosis treatment.

A physical examination should be performed, and a chest radiograph, microscopic examination, culture, and NAA testing of sputum or other relevant specimens should also be obtained, including gastric aspirates (125), as indicated (53,126,131,130). Because 15%–20% of patients with TB disease have negative TST results, a negative TST result is of limited value in the evaluation of the patient with suspected TB disease, particularly in patients from high TB incidence groups in whom TST positive rates exceed 30% (31).

Whenever feasible, perform bronchoscopy in a room that meets the ventilation requirements for an AII room (same as the AIA guidelines parameters for bronchoscopy rooms) (see Environmental Controls). Air-cleaning technologies (e.g., HEPA filtration and UVGI) can be used to increase equivalent ACH.

If sputum specimens must be obtained and the patient cannot produce sputum, consider sputum induction before bronchoscopy (111), 99 Bottles 1.0 crack serial keygen. In a patient who is intubated and mechanically ventilated, minimize the opening of circuitry. At least N95 respirators should be worn by HCWs while present during a bronchoscopy procedure on a patient with suspected or confirmed infectious TB disease. Because of the increased risk for M. tuberculosis transmission during the performance of bronchoscopy procedures on patients with TB disease, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a powered air-purifying respirator [PAPR] [29]) (see Respiratory Protection).

After bronchoscopy is 99 Bottles 1.0 crack serial keygen on a patient with suspected or confirmed infectious TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). During the period after bronchoscopy when the patient is still coughing, collect at least one sputum for AFB to increase the yield of the procedure. Patients with suspected or confirmed TB disease who are undergoing bronchoscopy should be kept in an AII room until coughing subsides.

Sputum Induction and Inhalation Therapy Rooms

Sputum induction and inhalation therapy induces coughing, which increases the potential for transmission of M. tuberculosis (87,88,90). Therefore, 99 Bottles 1.0 crack serial keygen, appropriate precautions should be taken when working with patients with suspected or confirmed TB disease, 99 Bottles 1.0 crack serial keygen. Sputum induction procedures for persons with suspected or confirmed TB disease should be considered after determination that self-produced sputum collection is inadequate and that the AFB smear result on other specimens collected is negative. HCWs who order or perform sputum induction or inhalation therapy in an environment without proper controls for the purpose of diagnosing conditions other than TB disease should assess the patient's risk for TB disease.

Cough-inducing or aerosol-generating procedures in patients with diagnosed TB should be conducted only after an assessment of infectiousness has been considered for each patient and should be conducted in an environment with proper controls. Sputum induction should be performed by using local exhaust ventilation (e.g., booths with special ventilation) or alternatively in a room that meets or exceeds the requirements of an AII room (see Environmental Controls) (90). At least an N95 disposable respirator should be worn by HCWs performing sputum inductions or inhalation therapy on a patient with suspected or confirmed infectious TB disease. Based on the risk assessment, 99 Bottles 1.0 crack serial keygen, consideration should be given to using a higher level of respiratory protection (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection) (90).

After sputum induction or inhalation therapy is performed on a patient with suspected or confirmed infectious TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). Patients with suspected or confirmed TB disease who are undergoing sputum induction or inhalation therapy should be kept in an AII room until coughing subsides.

Autopsy Suites

Autopsies performed on bodies with suspected or confirmed TB disease can pose a high risk for transmission of M. tuberculosis, particularly during the performance of aerosol-generating procedures (e.g., median sternotomy). Persons who handle bodies might be at risk for transmission of M. tuberculosis (77,78,171–177). Because certain CorelCAD 2021.5 With Crack Free Download performed as part of an autopsy might generate infectious aerosols, special airborne precautions are required.

Autopsies should not be performed on bodies with suspected or confirmed TB disease without adequate protection for those performing the autopsy procedures. Settings in which autopsies are performed should meet or exceed the requirements of an AII room, if possible (see Environmental Controls), and the drawing in the American Conference of Governmental Industrial Hygienists(r) (ACGIH) Industrial Ventilation Manual VS-99-07 (178). Air should be exhausted to the outside of the building, 99 Bottles 1.0 crack serial keygen. Air-cleaning technologies (e.g., HEPA filtration or UVGI) can be used to increase the number of equivalent ACH (see Environmental Controls).

As an added administrative measure, when performing autopsies on bodies with suspected or confirmed TB disease, coordination between attending physicians and pathologists is needed to ensure proper infection control and specimen collection. The use of local exhaust ventilation should be considered to reduce exposures to infectious aerosols (e.g., when using a saw, including Striker saw). For HCWs performing an autopsy on a body with suspected or confirmed TB disease, at least N95 disposable respirators should be worn (see Respiratory Protection). Based on the risk assessment, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection).

After an autopsy is performed on a body with suspected or confirmed TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (Tables 1 and 2). If time delay is not feasible, 99 Bottles 1.0 crack serial keygen, the autopsy staff should continue to wear respirators while they are in the room.

Embalming Rooms

Tissue or organ removal in an embalming room performed on bodies with suspected or confirmed TB disease can pose a high risk for transmission of M. tuberculosis, particularly during the performance of aerosol-generating procedures. Persons who handle corpses might be at risk for transmission of M. tuberculosis (77,78,171–176). Because certain procedures performed as part of embalming might generate infectious aerosols, special airborne precautions are required.

Embalming involving tissue or organ removal should not be performed on bodies with suspected or confirmed TB disease without adequate protection for the persons performing the procedures. Settings in which these procedures are performed should meet or exceed the requirements of an AII room, if possible (see Environmental Controls), and the drawing in the ACGIH Industrial Ventilation Manual VS-99-07 (178). Air should be exhausted to the outside of the building. Air-cleaning technologies (e.g., HEPA filtration or UVGI) can be used to increase the number of equivalent ACH 99 Bottles 1.0 crack serial keygen Environmental Controls). The use of local exhaust ventilation should be considered to reduce exposures to infectious aerosols (e.g., when using a saw, including Striker saw) and vapors from embalming fluids.

When HCWs remove tissues or organs from a body with suspected or confirmed TB disease, at least N95 disposable respirators should be worn (see Respiratory Protection). Based on the risk assessment, consider using a higher level of respiratory protection than an N95 disposable respirator (e.g., an elastomeric full-facepiece respirator or a PAPR) (see Respiratory Protection).

After tissue or organ removal is performed on a body with suspected or confirmed TB disease, allow adequate time to elapse to ensure removal of M. tuberculosis–contaminated room air before performing another procedure in the same room (see Environmental Controls). If time delay is not feasible, the staff should continue to wear respirators while in the room.

Outpatient Settings

Outpatient settings might include TB treatment facilities, dental-care settings, medical offices, ambulatory-care settings, and dialysis units. Environmental controls should be implemented based on the types of activities that are performed in the setting.

TB Treatment Facilities

TB treatment facilities might include TB clinics, infectious disease clinics, or pulmonary clinics. TB clinics and other settings in which patients with TB disease and LTBI are examined on a regular basis require special attention. The same principles of triage used in EDs and ambulatory-care settings (see Minimum Requirements) should be applied to TB treatment facilities. These principles include prompt identification, evaluation, and airborne precautions of patients with suspected or confirmed infectious TB disease.

All TB 99 Bottles 1.0 crack serial keygen staff, including outreach workers, should be screened for M. tuberculosis infection (Appendix C). Patients with suspected or confirmed 99 Bottles 1.0 crack serial keygen TB disease should be physically separated from all patients, but especially from those with HIV infection and other immunocompromising conditions that increase the likelihood of development of TB disease if infected. Immunosuppressed patients with suspected or confirmed infectious TB disease need to be physically separated from others to protect both the patient and others. Appointments should be scheduled to avoid exposing HIV-infected or otherwise severely immunocompromised persons to M. tuberculosis. Certain times of the day should be designated for appointments for patients with infectious TB disease or treat them in areas in which immunocompromised persons are not treated.

Persons with suspected or confirmed infectious TB disease should be promptly placed in an AII room to minimize exposure in the waiting room and other areas of the clinic, and they should be instructed to observe strict respiratory hygiene and cough etiquette procedures. Clinics that provide care for patients with suspected or confirmed infectious TB disease should have at least one AII room. The need for additional AII rooms should be based on the risk assessment for the setting.

All cough-inducing and aerosol-generating procedures should be performed using environmental controls (e.g., in a booth or an AII room) (see Environmental Controls). Patients should be left in the booth or AII room until coughing subsides. Another patient or HCW should not be allowed to enter the booth or AII room until sufficient time has elapsed for adequate removal of M, 99 Bottles 1.0 crack serial keygen. tuberculosis-contaminated air (see Environmental Controls). A respiratory-protection program should be implemented for all HCWs who work in the TB clinic and who enter AII rooms, 99 Bottles 1.0 crack serial keygen, visit areas in which persons with suspected or confirmed TB disease are located, or transport patients with suspected or confirmed TB disease in vehicles. When persons with suspected or confirmed infectious TB disease are in the TB clinic and not in an AII room, they should wear a surgical or procedure mask, if possible.

Medical Offices and Ambulatory-Care Settings

The symptoms of TB disease are usually symptoms for which patients might seek treatment in a medical office. Therefore, infectious TB disease could possibly be encountered in certain medical offices and ambulatory-care settings.

Because of the potential for M. tuberculosis transmission in medical offices and ambulatory-care settings, follow the general recommendations for management of patients with suspected or confirmed TB disease and the specific recommendations for EDs (see Intensive Care Units [ICUs]). The risk assessment may be used to determine the need for or selection of environmental controls and the frequency of testing HCWs for M. tuberculosis infection.

Dialysis Units

Certain patients with TB disease need chronic dialysis for treatment of ESRD (179–181), 99 Bottles 1.0 crack serial keygen. The incidence of TB disease and infection in patients with ESRD might be higher than in the general population (181–183) and might be compounded by the overlapping risks for ESRD and TB disease among patients with diabetes mellitus (39). In addition, certain dialysis patients or patients who are otherwise immunocompromised (e.g., patients with organ transplants) might be on immunosuppressive medications (162,183), 99 Bottles 1.0 crack serial keygen. Patients with ESRD who need chronic dialysis should have at least one test for M. tuberculosis infection to determine the need for treatment of LTBI, 99 Bottles 1.0 crack serial keygen. Annual re-screening is indicated if ongoing exposure of ESRD patients to M. tuberculosis is probable.

Hemodialysis procedures should be performed on hospitalized patients with suspected or confirmed TB disease in an AII room. Dialysis staff should use recommended respiratory protection, at least an N95 disposable respirator. Patients with suspected or confirmed TB disease who need chronic hemodialysis might need referral to a hospital or other setting with the ability to perform dialysis procedures in an AII room until the patient is no longer infectious or another diagnosis is made. Certain antituberculosis medications are prescribed differently for hemodialysis patients (31).

Dental-Care Settings

The generation of droplet nuclei 99 Bottles 1.0 crack serial keygen M. tuberculosis as a result of dental procedures has not been demonstrated (184). Nonetheless, oral manipulations during dental procedures could stimulate coughing and dispersal of infectious particles. Patients and dental HCWs share the same air space for varying periods, 99 Bottles 1.0 crack serial keygen, which contributes to the potential for transmission of M. tuberculosis in dental settings (185). For example, during primarily routine dental procedures in a dental setting, MDR TB 99 Bottles 1.0 crack serial keygen have been transmitted between two dental workers (186).

To prevent the transmission of M. tuberculosis in dental-care settings, certain recommendations should be followed (187,188). Infection-control policies for each dental health-care setting should be developed, based on the community TB risk assessment (Appendix B), and should be reviewed annually, if possible. The policies should include appropriate screening for 99 Bottles 1.0 crack serial keygen and TB disease for dental HCWs, education on the risk for transmission to the dental HCWs, and provisions for detection and management of patients who have suspected or confirmed TB disease.

When taking 99 Bottles 1.0 crack serial keygen patient's initial medical history and at periodic updates, dental HCWs should routinely document whether the patient has symptoms or signs of TB disease. If urgent dental care must be provided for a patient who has suspected or confirmed infectious TB disease, dental care should be provided in a setting that meets the requirements for an AII room (see Environmental Controls). Respiratory protection (at least N95 disposable respirator) should be used while performing procedures on such patients.

In dental health-care settings that routinely provide care to populations at high risk for TB disease, using engineering controls (e.g., portable HEPA units) similar to those used in waiting rooms or clinic areas of health-care settings with a comparable community-risk profile might be beneficial.

During clinical assessment and evaluation, a patient with suspected or confirmed TB disease should be instructed to observe strict respiratory hygiene and cough etiquette procedures (122). The patient should also wear a surgical or procedure mask, if possible. Non-urgent dental treatment should be postponed, and these patients should be promptly referred to an appropriate medical setting for evaluation of possible infectiousness. In addition, these patients should be kept in the dental health-care setting no longer than required to arrange a referral.

Nontraditional Facility-Based Settings

Nontraditional facility-based settings include EMS, medical settings in correctional facilities, home-based health-care and outreach settings, long-term–care settings (e.g., hospices and skilled nursing facilities), and homeless shelters. Environmental controls should be implemented based on the types of activities that are performed in the setting.

TB is more common in the homeless population than in the general population (189–192). Because persons who visit homeless shelters frequently share exposure and risk characteristics of TB patients who are treated in outpatient clinics, homeless shelters with clinics should observe the same TB infection-control measures as outpatient clinics. ACET has developed recommendations to assist health-care providers, health departments, shelter operators and workers, social service agencies, and homeless persons to prevent and control TB in this population (189).

Emergency Medical Services (EMS)

Although the overall risk is low (193), documented transmission of M. tuberculosis has occurred in EMS occupational settings (194), and approaches to reduce this risk have been described (193,195). EMS personnel should be included in a comprehensive screening program to test for M. tuberculosis infection and provide baseline screening and follow-up testing as indicated by the risk classification of the setting. Persons with suspected or confirmed infectious TB disease who are transported in an ambulance should wear a surgical or procedure mask, if possible, and drivers, HCWs, and other staff who are transporting the patient might consider wearing an N95 respirator.

The ambulance ventilation system should be operated in the nonrecirculating mode, and the maximum amount of outdoor air should be provided to facilitate dilution. If the vehicle has a rear exhaust fan, use this fan during transport. If the vehicle is equipped with a supplemental recirculating ventilation unit that passes air through HEPA filters before returning it to the vehicle, use this unit to increase the number of ACH (188). Air should flow from the cab (front of vehicle), over the patient, and out the rear exhaust fan. If an ambulance is not used, the ventilation system for the vehicle should bring in as much outdoor air as possible, and the system should be set to nonrecirculating. If possible, physically isolate the cab from the rest of the vehicle, and place the patient in the rear seat (194).

EMS personnel should 99 Bottles 1.0 crack serial keygen included in the follow-up contact investigations of patients with infectious TB disease. The Ryan White Comprehensive AIDS Resource Emergency Act of 1990 (Public law 101–381) mandates notification of EMS personnel after they have been exposed to a patient with suspected or confirmed infectious TB disease (Title 42 U.S. Code 1994) (http://hab.hrsa.gov/data2/adap/introduction.htm).

Medical Settings in Correctional Facilities

TB is a substantial health concern in correctional facilities; employees and inmates are at high risk (105,196–205). TB outbreaks in correctional facilities can lead to transmission in surrounding communities (201,206,207). ACET recommends that all correctional facilities have a written TB infection-control plan (196), and multiple studies indicate that screening correctional employees and inmates is a vital TB control measure (204,208,209).

The higher risk for M. tuberculosis transmission in health-care settings in correctional facilities (including jails and prisons) is a result of the disproportionate number of inmates with risk factors Sound Recorder 3.4.5 crack serial keygen TB infection and TB disease (203,210). Compared with the general population, TB prevalence is higher among inmates and is associated with a higher prevalence of HIV infection (197), 99 Bottles 1.0 crack serial keygen illicit substance use, lower socioeconomic status (201), and their presence in settings that are at high risk for transmission of M. tuberculosis.

A TB infection-control plan should be developed specifically for that setting, even if the institution is part of a multifacility system (196,211). Medical settings in correctional facilities should be classified as at least medium risk; therefore, all correctional facility health-care personnel and other staff, including correctional officers should be screened for TB at least annually (201,203,208).

Correctional facilities should collaborate with the local or state health department to decide on TB contact investigations and discharge planning (105,212) and to provide TB training and education to inmates and employees (196). Corrections staff should be educated regarding symptoms and signs of TB disease and encouraged to facilitate prompt evaluation of inmates with suspected infectious TB disease (206).

At least one AII room should be available in correctional facilities. Any inmate with suspected or confirmed infectious TB disease should be placed in an AII room immediately or transferred to a setting with an AII room; base the number of additional AII rooms needed on the risk assessment for the setting. Sputum samples should be collected in sputum induction booths or AII rooms, not in inmates' cells. Sputum collection can also be performed safely outside, away from other persons, windows, and ventilation intakes.

Inmates with suspected or confirmed infectious TB disease who must be transported outside an AII room for medically essential procedures should wear a surgical or procedure mask during transport, if possible. If risk assessment indicates the need for respiratory protection, drivers, medical or security staff, and others who are transporting patients with suspected or confirmed infectious TB disease in an enclosed vehicle should consider wearing an N95 disposable respirator.

A respiratory-protection program, including training, education, and fit-testing in the correctional facility's TB infection-control program should be implemented. Correctional facilities should maintain a tracking system for inmate TB screening and treatment and establish a mechanism for sharing this information with state and local health departments and other correctional facilities (196,201). Confidentiality of inmates should be ensured during screening for symptoms or signs of TB disease and risk factors.

Home-Based Health-Care and Outreach Settings

Transmission of M. tuberculosis has been documented in staff who 99 Bottles 1.0 crack serial keygen in home-based health-care and outreach settings (213,214). The setting's infection-control plan should include training that reminds HCWs who provide medical services in the homes of patients or other outreach settings of the importance of early evaluation of symptoms or signs of TB disease for early detection and treatment of TB disease. Training should also include the role of the HCW in educating patients regarding the importance of reporting symptoms or signs of TB disease and the importance of reporting any adverse effects to treatment for LTBI or TB disease.

HCWs who provide medical services in the homes of patients with suspected or confirmed TB disease can help prevent transmission of M. tuberculosis by 1) educating patients and other household members regarding the importance of taking medications as prescribed, 2) facilitating medical evaluation of symptoms or signs of TB disease, and 3) administering DOT, including DOT for treatment of LTBI whenever feasible.

HCWs who provide medical services in the homes of patients should not perform cough-inducing or aerosol-generating procedures on patients with suspected or confirmed infectious TB disease, because recommended infection controls probably will not be in place. Sputum collection should be performed outdoors, away from other persons, windows, and ventilation intakes.

HCWs who provide medical services in the homes of patients with suspected or confirmed infectious TB disease should instruct TB patients to observe strict respiratory hygiene and cough etiquette procedures, 99 Bottles 1.0 crack serial keygen. HCWs who enter homes of persons with suspected or confirmed infectious TB disease or who transport such persons in an enclosed vehicle should consider wearing at least an N95 disposable respirator (see Respiratory Protection).

Long-Term–Care Facilities (LTCFs)

TB poses a health risk to patients, HCWs, visitors, and volunteers in LTCFs (e.g., hospices and skilled nursing facilities) (215,216). Transmission of M. tuberculosis has occurred in LTCF (217–220), and pulmonary TB disease has been documented in HIV-infected patients and other immunocompromised persons residing in hospices (218,221,222). New employees and residents to these settings should receive a symptom screen and possibly a test for M. tuberculosis infection (see TB Risk Assessment Worksheet).

LTCFs must have adequate administrative and environmental controls, including airborne precautions capabilities and a respiratory-protection program, if they accept patients with suspected or confirmed infectious TB disease. The setting should have 1) a written protocol for the early identification of patients with symptoms or signs of TB disease and 2) procedures for referring these patients to a setting where they can be evaluated and managed. Patients with suspected or confirmed infectious TB disease should not stay in LTCFs unless adequate administrative and environmental controls and a respiratory-protection program are in place. Persons with TB disease who are determined to be noninfectious can remain in the LTCF and do not need to be in an AII room.

Training and Educating HCWs

HCW training and education regarding infection with M. tuberculosis and TB disease is an essential part of administrative controls in a TB surveillance or infection-control program. Training physicians and nurse 99 Bottles 1.0 crack serial keygen is especially essential because of the leadership role they frequently fulfill in infection control. HCW training and education can increase adherence to TB infection-control measures. Training and education should emphasize the increased risks posed by an undiagnosed person with TB disease in a health-care setting and the specific measures to reduce this risk. HCWs receive various types of training; therefore, combining training for TB infection control with other related trainings might be 99 Bottles 1.0 crack serial keygen TB Training and Education

The setting should document that all HCWs, including physicians, have received initial TB training relevant to their work setting and additional occupation-specific ConsoleAct [3.0] Windows and Office Activator Free Download. The level and detail of baseline training will vary according to the responsibilities of the HCW and the risk classification of the setting.

Educational materials on TB training are available from various sources at no cost in printed copy, on videotape (223), on compact discs, and the Internet. The local or state health department should have access to additional materials and resources and might be able to help develop a setting-specific TB education program. Suggested components of a baseline TB training program for HCWs have been described previously. CDC's TB website provides information regarding training and education materials (http://www.cdc.gov/tb). Additional training and education materials are available on CDC's TB Education and Training Resources website (http://www.findtbresources.org) and on other TB-related websites and resources (Appendix E).

Physicians, trainees, students, and other HCWs who work in a health-care setting but do not receive 99 Bottles 1.0 crack serial keygen from that setting should receive baseline training in TB infection-control policies and practices, the TB screening program, and procedures for reporting an M. tuberculosis infection test conversion or diagnosis of TB disease. Initial TB training should be provided before the HCW starts working.

Follow-Up TB Training and Education

All settings should conduct an annual evaluation of the need for follow-up training and education for HCWs based on the number of untrained and new HCWs, changes in the organization and services of the setting, 99 Bottles 1.0 crack serial keygen, and availability of new TB infection-control information.

If a potential or known exposure to M. tuberculosis occurs in the setting, prevention and control measures should include retraining HCWs in the infection-control procedures established to prevent the recurrence of exposure. If a potential or known exposure results in a newly recognized positive TST or BAMT result, test conversion, or diagnosis of TB disease, education should include information on 1) transmission of M. tuberculosis, 2) noninfectiousness of HCWs with LTBI, and 3) potential infectiousness of HCWs with TB disease.

OSHA requires annual respiratory-protection training for HCWs who use respiratory devices (see Respiratory Protection). HCWs in settings with a classification of potential ongoing transmission should receive additional training and education on 1) symptoms and signs of TB disease, 2) M. tuberculosis transmission, 3) infection-control policies, 4) importance of TB screening for HCWs, and 5) responsibilities of employers and employees regarding M. tuberculosis infection test conversion and diagnosis of TB disease.

TB Infection-Control Surveillance

HCW Screening Programs for TB Support Surveillance and Clinical Care

TB screening programs provide critical information for caring for individual HCWs and information that facilitates detection of M. tuberculosis transmission. The screening program consists of four major components: 1) baseline testing for M, 99 Bottles 1.0 crack serial keygen. tuberculosis infection, 2) serial testing for M. tuberculosis infection, 3) serial screening for symptoms or signs of TB disease, and 4) TB training and education.

Surveillance data from HCWs can protect both HCWs and patients. Screening can prevent future transmission by identifying lapses in infection control and expediting treatment for persons with LTBI or TB disease. Tests to screen for M. tuberculosis infection should be administered, interpreted, and recorded according to procedures in this report (see Supplement, Diagnostic Procedures for LTBI and TB Disease). Protection of privacy and maintenance of confidentiality of HCW test results should be ensured. Methods to screen for infection with M. tuberculosis are available (30,31,39).

Baseline Testing for M. tuberculosis Infection

Baseline testing for M. tuberculosis infection is recommended for all newly hired HCWs, regardless of the risk classification of the setting and can be conducted with the TST or BAMT. Baseline testing is also recommended for persons who will receive serial TB screening (e.g., residents or staff of correctional facilities or LTCFs) (39,224). Certain settings, with the support of the infection-control committee, might choose not to perform baseline or serial TB screening for HCWs who will never be in contact with or have shared air space with patients who have TB disease (e.g., telephone operators who work in a separate building from patients) or who will never be in contact with clinical specimens that might contain M. tuberculosis.

Baseline test results 1) provide a basis for comparison in the event of a potential or known exposure to M. tuberculosis and 2) facilitate the detection and treatment of LTBI or TB disease 99 Bottles 1.0 crack serial keygen an HCW before employment begins and reduces the risk to patients and other HCWs. If TST is used for baseline testing, two-step testing is recommended for HCWs whose initial TST results are negative (39,224). If the first-step TST result is negative, the second-step TST should be administered 1–3 weeks after the first TST result was read. If either 1) the baseline first-step TST result is positive or 2) the first-step TST result is negative but the second-step TST result is positive, TB disease should be excluded, RealVNC Serial key Archives if it is excluded, then the HCW should be evaluated for treatment of LTBI. If the first and second-step TST results are both negative, the person is classified as not infected with M. tuberculosis.

If the second test result of a two-step TST is not read within 48–72 hours, administer a TST as soon as possible (even if several months have elapsed) and ensure that the result is read within 48–72 hours (39). Certain studies indicate that positive TST reactions might still be measurable from 4–7 days after testing (225,226). However, if a patient fails to return within 72 hours and has a negative test result, the TST should be repeated (42).

A positive result to the second step of a baseline two-step TST is probably caused by boosting as opposed to recent infection with M. tuberculosis. These responses might result from remote infections with M. tuberculosis, infection with an NTM (also known as MOTT), or previous BCG vaccination. Two-step testing will minimize the possibility that boosting will lead to an unwarranted suspicion of transmission of M. tuberculosis with subsequent testing. A second TST is not needed if the HCW has a documented TST result from any time during the previous 12 months (see Baseline Testing for M. tuberculosis Infection After TST Within the Previous 12 Months).

A positive TST reaction as a result of BCG wanes after 5 years. Therefore, HCWs with previous BCG vaccination will frequently have a negative TST result (74,227–232). Because HCWs with a history of BCG are frequently from high TB-prevalence countries, positive test results for M. tuberculosis infection in HCWs with previous BCG vaccination should be interpreted as representing infection with M. tuberculosis (74,227–233). Although BCG reduces the occurrence of severe forms of TB disease in children and overall might reduce the risk for progression from LTBI to TB disease (234,235), BCG is not thought to prevent M. tuberculosis infection (236). Test results for M. tuberculosis infection for HCWs with a history of BCG should be interpreted by using the same diagnostic cut points used for HCWs without a history of BCG vaccination.

BAMT does not require two-step testing and is more specific than skin testing. BAMT that uses M. tuberculosis-specific antigens (e.g., QFT-G) are not PUBG PC Archives - Windows Activator to result in false-positive results in persons vaccinated with BCG. Baseline test results should be documented, preferably within 10 days of HCWs starting employment.

Baseline Testing for M. tuberculosis Infection After TST Within the Previous 12 Months

A second TST is not needed if the HCW has a documented TST result from any time during the previous 12 months. If a newly employed HCW has had a documented negative TST result within the previous 12 months, 99 Bottles 1.0 crack serial keygen, a single TST can be administered in the new setting (Box 1). This additional TST represents the second stage of two-step testing. The second test decreases the possibility that boosting on later testing will lead to incorrect suspicion of transmission of M. tuberculosis in the setting.

A recent TST (performed in ≤12 months) is not a contraindication to a subsequent TST unless the Hide All IP 2020.01.13 + Crack [Pro Version] Free Full 2021 Download was associated with severe ulceration or anaphylactic shock, which are substantially rare adverse events (30,237–239). Multiple TSTs are safe and do not increase the risk for a false-positive result or a TST conversion in persons without infection with mycobacteria (39).

Baseline Documentation of a History of TB Disease, a Previously 99 Bottles 1.0 crack serial keygen Test Result for M. tuberculosis Infection, or Completion of Treatment for LTBI or TB Disease

Additional tests for M. tuberculosis infection do not need to be performed for HCWs with a documented history of TB disease, documented previously positive test result for M. tuberculosis infection, or documented completion of treatment for LTBI or TB 99 Bottles 1.0 crack serial keygen. Documentation of a 99 Bottles 1.0 crack serial keygen positive test result for M. tuberculosis infection can be substituted for a baseline test result if the documentation includes a recorded TST result in millimeters (or BAMT result), including the concentration of cytokine measured (e.g., IFN-γ). All other HCWs should undergo baseline testing for M. tuberculosis infection to ensure that the test result on record in the setting has been performed and measured using the recommended diagnostic the recommended procedures (see Supplement, Diagnostic Procedures for LTBI and TB Disease).

A recent TST (performed in ≤12 months) is not a contraindication to the administration of an additional test unless the TST was associated with severe ulceration or anaphylactic shock, which are substantially rare adverse events (30,237,238). However, the recent test might complicate interpretation of subsequent test results because of the possibility of boosting.

Serial Follow-Up of TB Screening and Testing for M. tuberculosis Infection

The need for serial follow-up screening for groups of HCWs with negative test results for M. tuberculosis infection is an institutional decision that is based on the setting's risk classification. This decision and changes over time based on updated risk assessments should be official and documented, 99 Bottles 1.0 crack serial keygen. If a serial follow-up screening program is required, the risk assessment for the setting (Appendix B) will determine which HCWs should be included in the program and the frequency of screening, 99 Bottles 1.0 crack serial keygen. Two-step TST testing should not be performed for follow-up testing.

If possible, stagger follow-up screening (rather than testing all HCWs at the same time each year) so that all HCWs who work in the same area or profession are not tested in the same month. Staggered screening of HCWs (e.g., on the anniversary of their employment or on their birthdays) increases opportunities for early recognition of infection-control problems that can lead to conversions in test results for M. tuberculosis infection. Processing aggregate analysis of TB screening data on a periodic regular basis is important for detecting problems.

HCWs with a Newly Recognized Positive Test Result for M. tuberculosis Infection or Symptoms or Signs of TB Disease

Clinical Evaluation

Any HCW with a newly recognized positive test result for M. tuberculosis infection, test conversion, or symptoms or signs of TB disease should be promptly evaluated. The evaluation should be arranged with employee health, the local or state health department, or a personal physician. Any physicians who evaluate HCWs with suspected TB disease should be familiar with current diagnostic and therapeutic guidelines for LTBI and TB disease (31,39).

The definitions for positive test results for M. tuberculosis infection and test conversion in HCWs are included in this report (see Supplement, Diagnostic Procedures for LTBI and TB Disease), 99 Bottles 1.0 crack serial keygen. Symptoms of disease in the lung, pleura, or airways, and the larynx include coughing for ≥3 weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum or hemoptysis, hoarseness, fever, 99 Bottles 1.0 crack serial keygen, fatigue, or chest pain. The evaluation should include a clinical examination and symptom screen (a procedure used during a clinical evaluation in which patients are asked if they have experienced any symptoms or signs of TB disease), chest radiograph, and collection of sputum specimens.

If TB disease is diagnosed, begin antituberculosis treatment immediately, according to published guidelines (31). The diagnosing clinician (who might not be a physician with the institution's infection-control program) should notify the local or state health department in accordance with disease reporting laws, which generally specify a 24-hour time limit.

If TB disease is excluded, offer the HCW treatment for LTBI in accordance with published guidelines (see Supplements, Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease [39,240]). If the HCW has already completed treatment for LTBI and is part of a TB screening program, instead of participating in serial skin testing, the HCW should be monitored for symptoms of TB disease and should receive any available training, which should include information on the symptoms of TB disease and instructing the HCW to report any such symptoms immediately to occupational health, 99 Bottles 1.0 crack serial keygen. In addition, annual symptom screens should be performed, which can be administered as part of other HCW screening and education efforts. Treatment for LTBI should be offered to HCWs who are eligible (39).

HCWs with a previously negative test result who have an increase of ≥10 mm induration when examined on follow-up testing probably have acquired M. tuberculosis infection and should be evaluated for TB disease. When disease is excluded, HCWs should be treated for LTBI unless medically contraindicated (39,240).

Chest Radiography

HCWs with a baseline positive or newly positive TST or BAMT result should receive one chest radiograph to exclude a diagnosis of TB disease (or an interpretable copy within a reasonable time frame, such as 6 months). After this baseline chest radiograph is performed 99 Bottles 1.0 crack serial keygen the result is documented, repeat radiographs are not needed unless symptoms or signs of TB disease develop or a clinician recommends a repeat chest radiograph (39,116). Instead of participating in serial testing for M. tuberculosis infection, HCWs with a positive test result for M. tuberculosis infection should receive a symptom screen. The frequency of this symptom screen should be determined by the risk classification for the setting.

Serial follow-up chest radiographs are not recommended for HCWs with documentation of a previously positive test result for M. tuberculosis infection, treatment for LTBI or TB disease, or for asymptomatic HCWs with negative test results for M. tuberculosis infection. HCWs who have a previously positive test result for M. tuberculosis infection and who change jobs should carry documentation of a baseline chest radiograph result (and the positive test result for M. tuberculosis infection) to their new employers.

Workplace Restrictions

HCWs with a baseline positive or newly positive test result for M, 99 Bottles 1.0 crack serial keygen. tuberculosis infection should receive one chest radiograph result to exclude TB disease (or an interpretable copy within a reasonable time frame, such as 6 months).

HCWs with confirmed infectious pulmonary, laryngeal, endobroncheal, or tracheal TB disease, or a draining TB skin lesion pose a risk to patients, HCWs, and others. Such HCWs should be excluded from the workplace and should be allowed to return to work when the following criteria have been met: 1) three consecutive sputum samples (109–112) collected in 8–24-hour intervals that are negative, with at least one sample from 99 Bottles 1.0 crack serial keygen early morning specimen (because respiratory secretions pool overnight); 2) the person has responded to antituberculosis treatment that will probably be effective (can be based on susceptibility results); and 3) the person is determined to be noninfectious by a physician knowledgeable and experienced in managing TB disease (see Supplements, Estimating the Infectiousness of a TB Patient; Diagnostic Procedures for LTBI and TB Disease; and Treatment Procedures for LTBI and TB Disease).

HCWs with extrapulmonary TB disease usually do not need to be excluded from the workplace as long as no involvement of the respiratory track has occurred. They can be confirmed as noninfectious and can continue to work if documented evidence is available that indicates that concurrent pulmonary TB disease has been excluded.

HCWs receiving treatment for LTBI can return to work immediately. HCWs with LTBI who cannot take or do not accept or complete a full course of VSDC Video Editor Pro 6.7.5.302 With Crack Download [Latest] for LTBI should not be excluded from the workplace. They should be counseled regarding the risk for developing TB disease and instructed to report any TB symptoms immediately to the occupational health unit.

HCWs who have a documented positive TST or BAMT result and who leave employment should be counseled again, if possible, regarding the risk for developing TB disease and instructed to seek prompt evaluation with the local health department or their primary care physician if symptoms of TB disease develop, 99 Bottles 1.0 crack serial keygen. Consider mailing letters to former HCWs who have LTBI. This information should be recorded in the HCWs' employee health record when they leave employment.

Asymptomatic HCWs with a baseline positive or newly positive TST or BAMT result do not need to be excluded from the workplace. Treatment for LTBI should be considered in accordance with CDC guidelines (39).

Identification of Source Cases and Recording of Drug-Susceptibility Patterns

If an HCW experiences a conversion in a test result for M. tuberculosis infection, evaluate the HCW for a history of suspected or known 99 Bottles 1.0 crack serial keygen to M. tuberculosis to determine the potential source, 99 Bottles 1.0 crack serial keygen. When the source case is identified, also identify the drug susceptibility pattern of the M. tuberculosis isolate from the source. The drug-susceptibility pattern should be recorded in the HCW's medical or employee health record to guide the treatment of LTBI or TB disease, 99 Bottles 1.0 crack serial keygen, if indicated.

HCWs with Medical Conditions Associated with Increased Risk for Progression to TB Disease

In settings in which HCWs are severely immunocompromised, additional precautions must be taken. HIV infection is the highest risk factor for progression from LTBI to TB disease (22,39,42,49). Other immunocompromising conditions, including diabetes mellitus, certain cancers, and certain drug 99 Bottles 1.0 crack serial keygen, also increase the risk for rapid progression from LTBI to TB disease. TB disease can also adversely affect the clinical course of HIV infection and acquired immunodeficiency syndrome (AIDS) and can complicate HIV treatment (31,39,53).

Serial TB screening beyond that indicated by the risk classification for the setting is not indicated for persons with the majority of medical conditions that suppress the immune system or otherwise increase the risk for infection with M. tuberculosis progressing to TB disease (58). However, consideration should be given to repeating the TST for HIV-infected persons whose initial TST result was negative and whose immune function has improved in response to highly active antiretroviral therapy (HAART) (i.e., those whose CD4-T lymphocyte count has increased to >200 cells/mL).

All HCWs should, however, be encouraged during their initial TB training to determine if they have such a medical condition and should be aware that receiving medical treatment can improve cell-mediated immunity. HCWs should be informed concerning the availability of counseling, testing, and referral for HIV (50,51). In addition, HCWs should know whether they are immunocompromised, and they should be aware of the risks from exposure to M. tuberculosis (1). In certain cases, reassignment to areas in which exposure is minimized or nonexistent might be medically advisable or desirable.

Immunocompromised HCWs should have the option of an assignment in an area or activity where the risk for exposure to M. tuberculosis is low. This choice is a personal decision for the immunocompromised HCW (241) (http://www.eeoc.gov/laws/ada.html). Health-care settings should provide education and follow infection-control recommendations (70).

Information provided by HCWs regarding their immune status and request for voluntary work assignments should be treated confidentially, according to written procedures on the confidential handling of such information. All HCWs should be made aware of these procedures at the time of employment and during initial TB training and education.

Problem Evaluation

Contact investigations might be initiated in response to 1) conversions in test results in HCWs for M. tuberculosis infection, 2) diagnosis of TB disease in an HCW, 3) suspected person-to-person transmission of M. tuberculosis, 4) lapses in TB infection-control practices that expose HCWs and patients to M. tuberculosis, or 5) possible TB outbreaks identified using automated laboratory systems (242). In these situations, the objectives of a contact investigation might be to 1) determine the likelihood that transmission of M. tuberculosis has occurred; 2) determine the extent of M. tuberculosis transmission; 3) identify persons who were exposed, and, if possible, 99 Bottles 1.0 crack serial keygen, the sources of potential transmission; 4) identify factors that could have contributed to transmission, 99 Bottles 1.0 crack serial keygen, including failure of environmental infection-control measures, failure to follow infection-control procedures, or inadequacy of current measures or procedures; 5) implement recommended interventions; 6) evaluate the effectiveness of the interventions; and 7) ensure that exposure to M. tuberculosis has been terminated and that the conditions leading to exposure have been eliminated.

Earlier recognition of a setting in which M. tuberculosis transmission has occurred 99 Bottles 1.0 crack serial keygen be facilitated through innovative approaches to TB contact investigations (e.g., network analysis and genetic typing of isolates), 99 Bottles 1.0 crack serial keygen. Network analysis makes use of information (e.g., shared locations within a setting that might not be collected in traditional TB contact investigations) (45). This type of information might be useful during contact investigations involving hospitals or correctional settings to identify any shared wards, hospital rooms, or cells. Genotyping of isolates is universally available in the United States and is a useful adjunct in the investigation of M. tuberculosis 99 Bottles 1.0 crack serial keygen (44,89,243,244). Because the situations prompting an investigation are likely to vary, investigations should be tailored to the individual circumstances. Recommendations provide general guidance for conducting contact investigations (34,115).

General Recommendations for Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs

A test conversion might need to be reported to the health department, depending on state and local regulations. Problem evaluation during contact investigations should be accomplished through cooperation between infection-control personnel, occupational health, and the local or state TB-control program. If a test conversion in an HCW is detected as a result of serial screening and the source is not apparent, conduct a source case investigation to determine the probable source and the likelihood that transmission occurred in the health-care setting (115).

Lapses in TB infection control that might have contributed to the transmission of M. tuberculosis should be corrected. Test conversions and TB disease among HCWs should be recorded and reported, according to OSHA requirements (http://www.osha.gov/recordkeeping). Consult Recording and Reporting Occupational Injuries and Illness (OSHA standard 29 Code of Federal Regulations [CFR], 1904) to determine recording and reporting requirements (245).

Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Probable Source Outside the Health-Care Setting

If a test conversion in an HCW is detected and exposure outside the health-care setting has been documented by the corresponding local or state health department, terminate the investigation within the health-care setting.

Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Known Source in 99 Bottles 1.0 crack serial keygen Health-Care Setting

An investigation of a test conversion should be performed in collaboration with the local or state health department. If a conversion in an HCW is detected and the HCW's history does not document exposure outside the health-care setting but does identify a probable source in the setting, the following steps should be taken: 1) identify and evaluate close contacts of the suspected source case, including other patients and visitors; 2) determine possible reasons for the exposure; 3) implement interventions to correct the lapse(s) in infection control; and 4) immediately screen HCWs and patients if they were close contacts to the source case. For exposed HCWs and patients in a setting that has chosen to screen for infection with M. tuberculosis by using the TST, the following steps should be taken:

  • administer a symptom screen;
  • administer a TST to those who had previously negative TST results; baseline two-step TST should not be performed in contact investigations;
  • repeat the TST and symptom screen 8–10 weeks after the end of exposure, if the initial TST result is negative (33);
  • administer a symptom screen, if the baseline TST result is positive;
  • promptly evaluate (including a chest radiograph) the exposed person for TB disease, if the symptom screen or the initial or 8–10-week follow-up TST result is positive; and
  • conduct additional medical and diagnostic evaluation (which includes Corel VideoStudio Pro X2 crack serial keygen judgment about the extent of exposure) for LTBI, if TB disease is excluded.

If no additional conversions in the test results for M. tuberculosis infection are detected in the follow-up testing, terminate the investigation. If additional conversions in the tests for M. tuberculosis infection are detected in the follow-up testing, transmission might still be occurring, and additional actions are needed: 1) implement a classification of potential ongoing transmission for the specific setting or group of HCWs; 2) the initial cluster of test conversions should be reported promptly to the local or state health department; 3) possible reasons for exposure and transmission should be reassessed and 4) the degree of adherence to the interventions implemented should be evaluated.

Testing for M. tuberculosis infection should be repeated 8–10 weeks after the end of exposure for HCW contacts who previously had negative test results, and the circle of contacts should be expanded to include other persons who might have been exposed. If no additional TST conversions are detected on the second round of follow-up testing, 99 Bottles 1.0 crack serial keygen, terminate the investigation. If additional TST conversions are detected on the second round of follow-up testing, 99 Bottles 1.0 crack serial keygen, maintain a classification of potential ongoing transmission and consult the local or state health department or other persons with expertise in TB infection control for assistance.

The classification of potential ongoing transmission should be used as a temporary classification only. This classification warrants immediate investigation and corrective steps. After determination has been made that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Investigating a Conversion of a Test Result for M. tuberculosis Infection in an HCW with an Unknown Exposure

If a test conversion in an HCW is detected and the HCW's history does not document exposure outside the health-care setting and does not identify a probable source of exposure in the setting, additional investigation to identify a probable source in the health-care setting is warranted.

If no source case is identified, estimate the interval during which the HCW might have been infected. The interval is usually 8–10 weeks before the most recent negative test result through 2 weeks before the first positive test result, 99 Bottles 1.0 crack serial keygen. Laboratory and infection-control records should be reviewed to identify all patients (and any HCWs) who have had suspected or confirmed infectious TB disease and who might have transmitted M, 99 Bottles 1.0 crack serial keygen. tuberculosis to the HCW. If the investigation identifies a probable source, identify and evaluate contacts of the suspected source. Close contacts should be the highest priority for screening.

The following steps should be taken in a setting that uses TST or BAMT to screen for M. tuberculosis: 1) administer a symptom screen and the test routinely used in the setting (i.e., TST or BAMT) to persons who previously had negative results; 2) if the initial result is negative, the test and symptom screen should be repeated 8–10 weeks after the end of exposure; 3) if the symptom screen, the first test result, or the 8–10-week follow-up test result is positive, the presumed exposed person should be promptly evaluated for TB disease, including the use of a chest radiograph; and 4) if TB disease is excluded, additional medical and diagnostic evaluation for LTBI is needed, which includes a judgment regarding the extent of exposure (see Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs: Known Source in the Health-Care Setting).

Investigations That Do Not Identify a Probable Source

If serial TB screening is performed in the setting, review the results of screening of other HCWs in the same area of the health-care setting or same occupational group. If serial TB screening is not performed in the setting or if insufficient numbers of recent results are available, conduct additional TB screening of other HCWs in the same area or occupational group. If the review and screening yield no additional test conversions, and no evidence to indicate health-care–associated transmission exists, then the investigation should be terminated.

Whether HCW test conversions resulted from exposure in the setting or elsewhere or whether true infection with M. tuberculosis has even occurred is uncertain, 99 Bottles 1.0 crack serial keygen. However, the absence of other data implicating health-care–associated transmission suggests that the conversion could have resulted from 1) unrecognized exposure to M. tuberculosis outside the health-care setting; 2) cross reactivity with another antigen (e.g., LicenseCrawler 2.3 Build 2562 Crack Full Version Download or nontuberculous mycobacteria); or 3) errors in applying, reading, or interpreting the test result for M. tuberculosis infection, 99 Bottles 1.0 crack serial keygen. If the review and screening identify additional test conversions, health-care–associated transmission is more probable.

Evaluation of the patient identification process, TB infection-control policies and practices, and environmental controls to identify lapses that could have led to exposure and transmission should be conducted. If no problems are identified, a classification of potential ongoing transmission should be applied, and the local or state health department or other persons with expertise in TB infection control should be consulted for assistance. If problems are identified, implement recommended interventions and repeat testing for M. tuberculosis infection 8–10 weeks after the end of exposure for HCWs with negative test results. If no additional test conversions are detected in the follow-up testing, terminate the investigation.

Conversions in Test Results for 99 Bottles 1.0 crack serial keygen. tuberculosis Infection Detected in Follow-Up Testing

In follow-up testing, a classification of potential ongoing transmission should be maintained. Possible reasons for exposure and transmission should be reassessed, and the appropriateness of and degree of adherence to the interventions implemented should be evaluated. For HCWs with negative test results, repeat testing for M. tuberculosis infection 8–10 weeks after the end of exposure. The local or state health department or other persons with expertise in TB infection control should be consulted.

If no additional conversions are detected during the second round of follow-up testing, terminate the investigation. If additional conversions are detected, continue a classification of potential ongoing transmission and consult the local or state health department or other persons with expertise in TB infection control.

The classification of potential ongoing transmission should be used as a temporary classification only, 99 Bottles 1.0 crack serial keygen. This classification warrants immediate investigation and corrective steps. After a determination that ongoing transmission has ceased, the setting should be reclassified as medium risk. Maintaining the classification of medium risk for at least 1 year is recommended.

Investigating a Case of TB Disease in an HCW

Occupational health services and other physicians in the setting should have procedures for immediately notifying the local administrators or infection-control personnel if an HCW is diagnosed with TB disease so that a problem evaluation can be initiated. If an HCW is diagnosed with TB disease and does not have a previously documented positive test result for M. tuberculosis infection, 99 Bottles 1.0 crack serial keygen, conduct an investigation to identify the probable sources and circumstances for transmission (see General Recommendations for Investigating Conversions in Test Results for M. tuberculosis Infection in HCWs). If an HCW is diagnosed with TB disease, regardless of previous test result status, an additional investigation must be conducted to ascertain whether the disease was transmitted from this HCW to others, including other HCWs, patients, and visitors.

The potential infectiousness of the HCW, if potentially infectious, and the probable period of infectiousness (see Contact Investigations) should be determined. For HCWs with suspected or confirmed infectious TB disease, conduct an investigation that includes 1) identification of contacts (e.g., other HCWs, patients, and visitors), 2) evaluation of contacts for LTBI and TB disease, and 3) notification of the local or state health department for consultation and investigation of community contacts who were exposed outside the health-care setting.

M. tuberculosis genotyping should be performed so that the results are promptly available. Genotyping results are useful adjuncts to epidemiologically based public health investigations of contacts and possible source cases (especially in determining the role of laboratory contamination) (89,166,243,246–261). When ElcomSoft iOS Forensic Toolkit 7.0 Crack + Torrent (Mac) Lifetime! laws prevent the local or state health department from communicating information regarding a patient's identity, health department staff should work with hospital staff and legal counsel, and the HCW to determine how the hospital can be notified without breaching confidentiality.

Investigating Possible Patient-to-Patient Transmission of M. tuberculosis

Information concerning TB cases among patients in the setting should be routinely recorded for risk classification and risk assessment purposes. Documented information by location and date should include results of sputum smear and culture, chest radiograph, drug-susceptibility testing, and adequacy of infection-control measures.

Each time a patient with suspected or confirmed TB disease is encountered in a health-care setting, an assessment of the situation should be made and the focus should be on 1) a determination of infectiousness of the patient, 2) confirmation of compliance with local public health reporting requirements (including the prompt reporting of a person with suspected TB disease as required), 99 Bottles 1.0 crack serial keygen, and 3) assessment of the adequacy of infection control.

A contact investigation should be initiated in situations where infection control is inadequate and the patient is infectious. Patients with positive AFB sputum smear results are more infectious than patients with negative AFB sputum smear results, but the possibility exists that patients with negative sputum smear results might be infectious (262). Patients with negative AFB sputum smear results but who undergo aerosol-generating or aerosol-producing procedures (including bronchoscopy) without adequate infection-control measures create a potential for exposure. All investigations should be conducted in consultation with the local public health department.

If serial surveillance of these cases reveals one of the following conditions, 99 Bottles 1.0 crack serial keygen, patient-to-patient transmission might have occurred, and a contact investigation should be initiated:

  • A high proportion of patients with TB disease were admitted to or examined in the setting during the year preceding onset of their TB disease, especially when TB disease is identified in patients who were otherwise unlikely to be exposed to M. tuberculosis.
  • An increase occurred in the number of TB patients diagnosed with drug-resistant TB, compared with the previous year.
  • Isolates from multiple patients had identical and characteristic drug susceptibility or DNA fingerprint patterns.

Surveillance of TB Cases in Patients Indicates Possible Patient-to-Patient Transmission of M. tuberculosis

Health-care settings should collaborate with the local or state health department to conduct an investigation. For settings in which HCWs are serially tested for M. tuberculosis infection, review HCW records to determine whether an increase in the number of conversions in test results for M. tuberculosis infection has occurred. Patient surveillance data and medical records should be reviewed for additional cases of TB disease. Settings should look for possible exposures from previous or current admissions that might have exposed patients with newly diagnosed TB disease to other patients with TB disease, determining if the patients were admitted to the same room or area, or if they received the same procedure or went to the same treatment area on the same day.

If the investigation suggests that transmission has occurred, possible causes of transmission of M. tuberculosis (e.g., delayed diagnosis of TB disease, institutional barriers to implementing timely and correct airborne precautions, and inadequate environmental controls) should be evaluated. Possible exposure to other patients or HCWs should be determined, and if exposure has occurred, these persons should be evaluated for LTBI and TB disease (i.e., test for M. tuberculosis infection and administer a symptom screen).

If the local or state health department was not previously contacted, settings should notify the health department so that a community contact investigation can be initiated, if necessary. The possibility of laboratory errors in diagnosis or the contamination of bronchoscopes (82,169) or other equipment should be considered (136).

Contact Investigations

The primary goal of contact investigations is to identify secondary cases of TB disease and LTBI among contacts so that therapy can be initiated as needed (263–265). Contact investigations should be collaboratively conducted by both infection-control personnel and local TB-control program personnel.

Initiating a Contact Investigation

A contact investigation should be initiated when 1) a person with TB disease has been examined at a health-care setting, and TB disease was not diagnosed and reported quickly, resulting in failure to apply recommended TB infection controls; 2) environmental controls or other infection-control measures have malfunctioned while a person with TB disease was in the setting; or 3) an HCW develops TB disease and exposes other persons in the setting.

As soon as TB disease is diagnosed or a problem is recognized, standard public health practice should be implemented to prioritize the identification of other patients, HCWs, and visitors who might have been exposed to the index case before TB infection-control measures were correctly applied (52). Visitors of these patients might also be contacts or the source case.

The following activities should be implemented in collaboration with or by the local or state health department (34,266): 1) interview the index case and all persons who might have been exposed; 2) review the medical records of the index case; 3) determine the exposure sites (i.e., where the index case lived, worked, visited, or 99 Bottles 1.0 crack serial keygen hospitalized before being placed under airborne precautions); and 4) determine the infectious period of the index case, which is the period during which a person with TB disease is considered contagious and most capable of transmitting M. tuberculosis to others.

For programmatic purposes, for patients with positive AFB sputum smear results, the infectious period can be considered to begin 3 months before the collection date of the first positive AFB sputum smear result or the symptom onset date (whichever is earlier). The end of the infectious period is the date the patient is placed under airborne precautions or the date of collection of the first of consistently negative AFB sputum smear results (whichever is earlier). For patients with negative AFB sputum smear results, the infectious period can begin 1 month before the symptom onset date and end when the patient is placed under airborne precautions.

The exposure period, the time during which a person shared the same air space with a person with TB disease for each contact, should be determined as well as whether transmission occurred from the index patient to persons with whom the index patient had intense contact. In addition, the following should be determined: 1) intensity of the exposure based on proximity, 2) overlap with the infectious period of the index case, 3) duration of exposure, 4) presence or absence of infection-control measures, 5) infectiousness of the index case, 6) performance of procedures that could increase the risk for transmission during contact (e.g., sputum induction, bronchoscopy, and airway suction), and 7) the exposed cohort of contacts for TB screening.

The most intensely exposed HCWs and patients should be screened as soon as possible after exposure to M. tuberculosis has occurred and 8–10 weeks after the end of exposure if the initial TST result is negative. Close contacts should be the highest priority for screening.

For HCWs and patients who are presumed to have been exposed in a setting that screens for infection with M. tuberculosis using the TST, the following activities should be implemented:

  • performing a symptom screen;
  • administering a TST to those who previously had negative TST results;
  • repeating the TST and symptom screen 8–10 weeks after the end of exposure, if the initial TST result is negative;
  • promptly evaluating the HCW for TB disease, including performing a chest radiograph, if the symptom screen or the initial or 8–10-week follow-up TST result is positive; and
  • providing additional medical and diagnostic evaluation for LTBI, including determining the extent of exposure, if TB disease is excluded.

For HCWs and patients who are presumed to have been exposed in a setting that screens for infection with M. tuberculosis using the BAMT, the following activities should be implemented (see Supplement, Surveillance and Detection of M. tuberculosis Infections in Health-Care Settings). If the most intensely exposed persons have test conversions or positive 99 Bottles 1.0 crack serial keygen results for M. tuberculosis infection in the absence of a previous history of a positive test result or TB disease, expand the investigation to evaluate persons with whom the index patient had less contact. If the evaluation of the most intensely exposed contacts yields no evidence of transmission, expanding testing to others is not necessary.

Exposed persons with documented previously positive test results for M. tuberculosis infection do not require either repeat testing for M. tuberculosis infection or a chest radiograph (unless they are immunocompromised or otherwise at high risk for TB disease), but they should receive a symptom screen. If the person has symptoms of TB disease, 1) record the symptoms in the HCW's medical chart or employee health record, 2) perform a chest radiograph, 3) perform a full medical evaluation, and 4) obtain sputum samples for smear and culture, if indicated.

The setting should determine the reason(s) that a TB diagnosis or initiation of airborne precautions was delayed or procedures failed, which led to transmission of M. tuberculosis in the setting. Reasons and corrective actions taken should be recorded, including changes in policies, procedures, and TB training and education practices.

Collaboration with the Local or State Health Department

For assistance with the planning and implementation of TB-control activities in the health-care setting and for names of experts to help with policies, procedures, and program evaluation, settings should coordinate with the local or state TB-control program99 Bottles 1.0 crack serial keygen. By law, the local or state health department must be notified when TB disease is suspected or confirmed in a patient or HCW so that follow up can be arranged and a community contact investigation can 99 Bottles 1.0 crack serial keygen conducted. The local or state health department should be notified as early as possible before the patient is discharged to facilitate followup and continuation of therapy by DOT (31). For inpatient settings, coordinate a discharge plan with the patient (including a patient who is an HCW with TB disease) and the TB-control program of the local or state health department.

Environmental Controls

Environmental controls are the second line of defense in the TB infection-control program, after administrative controls. Environmental controls include technologies for the removal or inactivation of airborne M. tuberculosis. These technologies include local exhaust ventilation, general ventilation, HEPA filtration, and UVGI. These controls help to prevent the spread and reduce the concentration of infectious droplet nuclei in the air. A summary of environmental controls and their use in prevention of transmission of M. tuberculosis is provided in this report (see Supplement, Environmental Controls), including detailed information concerning the application of environmental controls.

Local Exhaust Ventilation

Local exhaust ventilation is a source-control technique used for capturing airborne contaminants (e.g., infectious droplet nuclei or other infectious particles) before they are dispersed into the general environment. In local exhaust ventilation methods, external hoods, enclosing booths, and tents are used. Local exhaust ventilation (e.g., enclosed, ventilated booth) should be used for cough-inducing and aerosol-generating procedures. When local exhaust is not feasible, perform cough-inducing and aerosol-generating procedures in a room that meets the requirements for an AII room.

General Ventilation

General ventilation systems dilute and remove contaminated air and control airflow patterns in a room or setting. An engineer or other professional with expertise in ventilation should be included as part of the staff of the health-care setting or hire a consultant with expertise in ventilation engineering specific to health-care settings. Ventilation systems should be designed to meet all applicable federal, state, and local requirements.

A single-pass ventilation system is the preferred choice in areas in which infectious airborne droplet nuclei might be Wondershare PDFelement Pro OCR 7.6.10 Crack FREE Download (e.g., AII rooms). Use HEPA filtration if recirculation of air is necessary.

AII rooms in health-care settings pre-existing 1994 guidelines should have an airflow of ≥6 ACH. When feasible, the airflow should be increased to ≥12 ACH by 1) adjusting or modifying the ventilation system or 2) using air-cleaning methods (e.g., room-air recirculation units containing HEPA filters or UVGI systems that increase the equivalent ACH). New construction or renovation of health-care settings should be designed so that AII rooms achieve an airflow of ≥12 ACH. Ventilation rates for other areas in health-care settings should meet certain specifications (see Risk Classification Examples). If a variable air volume (VAV) ventilation system is used in an AII room, design the system to maintain the room under negative pressure at all times. The VAV system minimum set point must be adequate to maintain the recommended mechanical and outdoor ACH and a negative pressure ≥0.01 inch of water gauge compared with adjacent areas.

Based on the risk assessment for the setting, the required number of AII rooms, other negative-pressure rooms, and local exhaust devices should be determined. The location of these rooms and devices will depend partially on where recommended ventilation conditions can be achieved. Grouping AII rooms in one area might facilitate the care of patients with TB disease and the installation and maintenance of optimal environmental controls.

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