Diversity of nontuberculoid Mycobacterium species in biofilms of urban and semiurban drinking water distribution systems

Nontuberculous mycobacteria (NTM) are ubiquitous and have been isolated from a variety of environmental sources, including water. Various NTM were isolated from biofilms in drinking water distribution systems in two urban and two semiurban areas in South Africa. Most of the isolates belonged to opportunistic pathogenic species of the NTM group, but none belonged to the Mycobacterium avium complex.     

Molecular Epidemiology of Nontuberculous Mycobacteria Isolates from Clinical and Environmental Sources of a Metropolitan City

Introduction

While NTM infection is mainly acquired from environmental exposure, monitoring of environmental niches for NTM is not a routine practice. This study aimed to find the prevalence of environmental NTM in soil and water in four highly populated suburbs of Tehran, Iran.

Material and Methods

A total of 4014 samples from soil and water resources were collected and studied. Sediments of each treated sample were cultured in Lowenstein-Jensen medium and observed twice per week for growth rate, colony morphology, and pigmentation. Colonies were studied with phenotypic tests. Molecular analysis was performed on single colonies derived from subculture of original isolates. Environmental samples were compared with 34 NTM isolates from patients who were residents of the study locations.

Results

Out of 4014 samples, mycobacteria were isolated from 862 (21.4%) specimens; 536 (62.1%) belonged to slow growing mycobacteria (SGM) and 326 (37.8%) were rapid growing mycobacteria (RGM). The five most frequent NTM were M. farcinogens (105/862; 12.1%), M. fortuitum (72/862; 8.3%), M. senegalense (58/862; 6.7%), M. kansasii (54/862; 6.2%), and M. simiae (46/862; 5.3%). In total, 62.5% (539/862) of mycobacterial positive samples were isolated from water and only 37.4% (323/862) of them were isolated from soil samples (P<0.05). Out of 5314 positive clinical samples for mycobacteria, 175 (3.2%) isolates were NTM. The trend of NTM isolates increased from 1.2% (13 out of 1078) in 2004 to 3.8% (39 out of 1005) in 2014 (P = 0.0001). The major clinical isolates were M. simiae (51; 29.1%), M. kansasii (26; 14.8%), M. chelonae (28; 16%), and M. fortuitum (13; 7.4%).

Conclusions

Comparing the distribution pattern of environmental NTM isolates with clinical isolates suggests a possible transmission link, but this does not apply to all environmental NTM species. Our study confirms an increasing trend of NTM isolation from clinical samples that needs further investigation.     

Spatio-temporal study of environmental nontuberculous mycobacteria isolated from Wardha district in Central India

During the last two decades, nontuberculous mycobacteria (NTM) have gained in importance but there is still a paucity of data, particularly for environmental isolates. We studied, over a period of two years, the spatio-temporal features of NTM isolates obtained from different environmental sources in Wardha district, India. A total of 1398 samples (699 each of soil and water) were tested and 170 (12.2%) yielded NTM isolates, including 123 from soil and 47 from water samples. Out of 170 NTM isolates, 107 (63%) belonged to potentially pathogenic mycobacteria (PPM) and 63 (37%) to the less pathogenic mycobacterial (LPM) group. Overall, maximum isolation was obtained in rainy season (20.3%) followed by winter (13.5%), post rainy (8.7%) and summer seasons (5.8%). Mycobacterium fortuitum, Mycobacterium gordonae and Mycobacterium avium complex (MAC) were common isolates followed by Mycobacterium flavescens, Mycobacterium scrofulaceum, Mycobacterium simiae and Mycobacterium marinum. From soil, isolation of NTM was highest from grounds used for community gatherings (42.8%) followed by soil from residential premises (27.7%) and near the wells (26.0%). From drinking water sources, highest NTM isolation was obtained from wells (15.4%) followed by treated water tanks (6.9%), household receptacles (6.3%), hand pumps (5.6%) and tap water supply (3.5%). Isolation from natural canal water was 6.6%, while from drainage and waste water ponds isolation was 8.3%. The results of the study revealed that in Wardha district, NTM are present both in the soil and drinking water. As NTM can be pathogenic, particularly in immune-compromised individuals, these can be of potential risk to the human population.     

Isolation and Identification of Environmental Mycobacteria in the Waters of a Hemodialysis Center

The use of poorly treated water during hemodialysis may lead to contamination with nontuberculous mycobacteria (NTM). This study aimed to isolate and identify NTM species in the water of a Brazilian hemodialysis center. We collected 210 samples of water from the hydric system of the unit (post-osmosis system, hemodialysis rooms, reuse system, and hemodialysis equipment) and from the municipal supply network; we isolated the NTM by a classic microbiological technique and identified them by the PCR restriction enzyme pattern of the hsp65 gene (PRA). Fifty-one (24.3 %) of the collected samples tested positive for NTM; both the municipal supply network (2 samples, 3.2 %) and the hydric system of the hemodialysis center (49 samples, 96.1 %) contained NTM. We isolated and identified potentially pathogenic bacteria such as Mycobacterium lentiflavum (59.0 %) and M. kansasii (5.0 %), as well as rarely pathogenic bacteria like M. gordonae (24.0 %), M. gastri (8.0 %), and M. szulgai (4.0 %). The ability of NTM to cause diseases is well documented in the literature. Therefore, the identification of NTM in the water of a Brazilian hemodialysis center calls for more effective water disinfection procedures in this unit.     

Nontuberculous mycobacteria: an emerging risk in engineered environmental habitats

Nontuberculous mycobacteria (NTM) are microorganisms commonly living in the environment. Nevertheless, most of them are opportunistic pathogens. To verify concentrations of NTM in some man-made habitats, analyses were performed on water and surface samples, and the data were correlated to the global microbiological quality of water. Most of the drinking water samples (98 %) complied with the microbial requirements established by the European Directive 98/83/EC on drinking water when Escherichia coli was considered. Low counts of heterotrophs were also obtained. NTM were isolated from 72 % of the analyzed samples. Tap water from private buildings, schools and hospitals provided positive results for NTM, with comparable densities ranging from 1 to 6?×10² CFU/L. NTM were also found in swimming pool water samples, with concentrations ranging from 29 to 3?×10⁴ CFU/L, as well as in 70 % of the surface sample. The most frequently isolated species were Mycobacterium mucogenicum, M. intracellulare and M. terrae. These yields confirm that no correlation exists between the monitoring controls carried out by law and the occurrence of these bacteria that may represent a potential risk, especially for immunocompromised people and vulnerable groups.     

Pyrosequence Analysis of the hsp65 Genes of Nontuberculous Mycobacterium Communities in Unchlorinated Drinking Water in the Netherlands

Studies have shown that certain opportunistic pathogenic species of nontuberculous mycobacteria (NTM) can be present in distributed drinking water. However, detailed information about NTM population composition in drinking water is lacking. Therefore, NTM communities in unchlorinated drinking water from the distribution system of five treatment plants in the Netherlands were characterized using 454 pyrosequencing of the hsp65 gene. Results showed high diversities in unchlorinated drinking water, with up to 28 different NTM operational taxonomic units (OTUs) in a single sample. Each drinking water sample had a unique NTM community, and most (81.1%) OTUs were observed only once. One OTU was observed in 14 of 16 drinking water samples, indicating that this NTM species is well adapted to unchlorinated drinking water conditions. A clear influence of season, source type (groundwater, surface water), easily assimilable organic carbon (AOC) concentration, biofilm formation rate, and active biomass in treated water on the establishment of an NTM community in drinking water was not observed. Apparently, local conditions are more important for the development of a specific NTM community in the drinking water distribution system. A low (4.2%) number of hsp65 gene sequences showed more than 97% similarity to sequences of the opportunistic pathogens M. avium, M. genavense, and M. gordonae. However, most (95.8%) NTM hsp65 gene sequences were related to not-yet-described NTM species that have not been linked to disease, indicating that most NTM species in unchlorinated drinking water from distribution systems in the Netherlands have a low public health significance.     

Using Syndromic Surveillance to Investigate Tattoo-Related Skin Infections in New York City

In response to two isolated cases of Mycobacterium chelonae infections in tattoo recipients where tap water was used to dilute ink, the New York City (NYC) Department of Health and Mental Hygiene conducted an investigation using Emergency Department (ED) syndromic surveillance to assess whether an outbreak was occuring. ED visits with chief complaints containing the key word “tattoo” from November 1, 2012 to March 18, 2013 were selected for study. NYC laboratories were also contacted and asked to report skin or soft tissue cultures in tattoo recipients that were positive for non-tuberculosis mycobacterial infection (NTM). Thirty-one TREDV were identified and 14 (45%) were interviewed to determine if a NTM was the cause for the visit. One ED visit met the case definition and was referred to a dermatologist. This individual was negative for NTM. No tattoo-associated NTM cases were reported by NYC laboratories. ED syndromic surveillance was utilized to investigate a non-reportable condition for which no other data source existed. The results were reassuring that an outbreak of NTM in tattoo recipients was not occurring. In response to concerns about potential NTM infections, the department sent a letter to all licensed tattoo artists advising them not to dilute tattoo ink with tap water.     

Persistence of Nontuberculous Mycobacteria in a Drinking Water System after Addition of Filtration Treatment

There is evidence that drinking water may be a source of infections with pathogenic nontuberculous mycobacteria (NTM) in humans. One method by which NTM are believed to enter drinking water distribution systems is by their intracellular colonization of protozoa. Our goal was to determine whether we could detect a reduction in the prevalence of NTM recovered from an unfiltered surface drinking water system after the addition of ozonation and filtration treatment and to characterize NTM isolates by using molecular methods. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration and ozonation after 6 months of sampling. Sample sites included those at treatment plant effluents, distributed water, and cold water taps (point-of-use [POU] sites) in public or commercial buildings located within each distribution system. NTM were recovered from 27% of the sites. POU sites yielded the majority of NTM, with >50% recovery despite the addition of ozonation and filtration. Closely related electrophoretic groups of Mycobacterium avium were found to persist at POU sites for up to 26 months. Water collected from POU cold water outlets was persistently colonized with NTM despite the addition of ozonation and filtration to a drinking water system. This suggests that cold water POU outlets need to be considered as a potential source of chronic human exposure to NTM.     

Environmental Nontuberculous Mycobacteria in the Hawaiian Islands

Lung disease caused by nontuberculous mycobacteria (NTM) is an emerging infectious disease of global significance. Epidemiologic studies have shown the Hawaiian Islands have the highest prevalence of NTM lung infections in the United States. However, potential environmental reservoirs and species diversity have not been characterized. In this cross-sectional study, we describe molecular and phylogenetic comparisons of NTM isolated from 172 household plumbing biofilms and soil samples from 62 non-patient households and 15 respiratory specimens. Although non-uniform geographic sampling and availability of patient information were limitations, Mycobacterium chimaera was found to be the dominant species in both environmental and respiratory specimens. In contrast to previous studies from the continental U.S., no Mycobacterium avium was identified. Mycobacterium intracellulare was found only in respiratory specimens and a soil sample. We conclude that Hawai’i’s household water sources contain a unique composition of Mycobacterium avium complex (MAC), increasing our appreciation of NTM organisms of pulmonary importance in tropical environments.     

Occurrence of Nontuberculous Mycobacteria in Environmental Samples

Nontuberculous mycobacteria (NTM) are a major cause of opportunistic infection in immunocompromised hosts. Because there is no evidence of person-to-person transmission and NTM have been found in drinking water, the environment is considered a likely source of infection. In this study the widespread occurrence of NTM was examined in drinking water, bottled water, and ice samples. A total of 139 samples were examined for NTM by a membrane filtration culture technique followed by PCR amplification and 16S rRNA sequence determination to identify the isolates. NTM were not detected in bottled water or cisterns but were detected in 54% of the ice samples and 35% of the public drinking-water samples from 21 states. The most frequently occurring isolate was M. mucogenicum (formerly referred to as an M. chelonae-like organism).     

Cooccurrence of Free-Living Amoebae and Nontuberculous Mycobacteria in Hospital Water Networks,and Preferential Growth of Mycobacterium avium in Acanthamoeba lenticulata

The incidence of lung and other diseases due to nontuberculous mycobacteria (NTM) is increasing. NTM sources include potable water, especially in households where NTM populate pipes, taps, and showerheads. NTM share habitats with free-living amoebae (FLA) and can grow in FLA as parasites or as endosymbionts. FLA containing NTM may form cysts that protect mycobacteria from disinfectants and antibiotics. We first assessed the presence of FLA and NTM in water and biofilm samples collected from a hospital, confirming the high prevalence of NTM and FLA in potable water systems, particularly in biofilms. Acanthamoeba spp. (genotype T4) were mainly recovered (8/17), followed by Hartmannella vermiformis (7/17) as well as one isolate closely related to the genus Flamella and one isolate only distantly related to previously described species. Concerning mycobacteria, Mycobacterium gordonae was the most frequently found isolate (9/17), followed by Mycobacterium peregrinum (4/17), Mycobacterium chelonae (2/17), Mycobacterium mucogenicum (1/17), and Mycobacterium avium (1/17). The propensity of Mycobacterium avium hospital isolate H87 and M. avium collection strain 104 to survive and replicate within various FLA was also evaluated, demonstrating survival of both strains in all amoebal species tested but high replication rates only in Acanthamoeba lenticulata. As A. lenticulata was frequently recovered from environmental samples, including drinking water samples, these results could have important consequences for the ecology of M. avium in drinking water networks and the epidemiology of disease due to this species.     

Occurrence of Nontuberculous Mycobacterial Pulmonary Infection in an Endemic Area of Tuberculosis

The majority of investigations of the epidemiology of nontuberculous mycobacteria (NTM) have focused on highly developed nations with a low prevalence of tuberculosis. In contrast, the Para state of north Brazil represents an area of high tuberculosis prevalence and increasing NTM incidence. Toward the goal of understanding the dynamics of infection by all Mycobacterium species, we report patient characteristics and the identification of NTM strains isolated from sputum samples from patients that were residents of Para, a state in the Amazon region, Northern of Brazil, over the period January 2010 through December 2011 (2 years). The 29 NTM patients comprised 13.5% of positive mycobacterial cultures over the 2-year period. A major risk factor for NTM pulmonary disease was previous tuberculosis (76%). Further, the average age of NTM patients (52 years) was significantly higher than that of tuberculosis patients (39 years) and more were female (72.4% vs. 37.4%). Unlike other Brazilian states, NTM pulmonary patients in Para were infected with a different spectrum of mycobacteria; primarily the rapidly growing Mycobacterium massiliense and Mycobacterium simiae complex.     

The Tracing of Mycobacteria in Drinking Water Supply Systems by Culture, Conventional, and Real Time PCRs

Mycobacteria are widely present in diverse aquatic habitats, where they can survive for months or years while some species can even proliferate. The resistance of different mycobacterial species to disinfection methods like chlorination or ozonation could result in their presence in the final tap water of consumers. In this study, the culture method, Mycobacterium tuberculosis complex conventional duplex PCR for detection of non-tuberculous mycobacteria (NTM) and quantitative real-time PCR (qPCR) to detect three subspecies of M. avium species (M. a. avium, M. a. hominissuis, and M. a. paratuberculosis) were used to trace their possible path of transmission from the watershed through the reservoir and drinking water plant to raw drinking water and finally to households. A total of 124 samples from four drinking water supply systems in the Czech Republic, 52 dam sediments, 34 water treatment plant sludge samples, and 38 tap water household sediments, were analyzed. NTM of 11 different species were isolated by culture from 42 (33.9 %) samples; the most prevalent were M. gordonae (16.7 %), M. triplex (14.3 %), M. lentiflavum (9.5 %), M. a. avium (7.1 %), M. montefiorenase (7.1 %), and M. nonchromogenicum (7.1 %). NTM DNA was detected in 92 (76.7 %) samples. By qPCR analysis a statistically significant decrease (P < 0.01) was observed along the route from the reservoir (dam sediments), through water treatment sludge and finally to household sediments. The concentrations ranged from 10⁰ to 10⁴ DNA cells/g. It was confirmed that drinking water supply systems (watershed–reservoir–drinking water treatment plant–household) might be a potential transmission route for mycobacteria.     

Comparison of Culture Methods for Isolation of Nontuberculous Mycobacteria from Surface Waters

The environment is the likely source of most nontuberculous mycobacteria (NTM) involved in human infections, especially pulmonary, skin, and soft tissue infections. In order to measure the prevalence of NTM in different aquatic ecosystems, we tried to standardize the culture methods used for surface water testing since many procedures have been described previously. Cultivation of mycobacteria requires long-term incubation in rich media and inactivation of rapidly growing microorganisms whose growth impedes observation of mycobacterial colonies. Consequently, the two criteria used for evaluation of the methods examined were (i) the rate of inhibition of nontarget microorganisms and (ii) the efficiency of recovery of mycobacteria. We compared the competitive growth of Mycobacterium chelonae and M. avium with nontarget microorganisms on rich Middlebrook 7H11-mycobactin medium after treatment by several chemical decontamination methods that included acids, bases, detergent, or cetylpyridinium chloride (CPC) with and without an antibiotic cocktail, either PANTA (40 U/ml polymyxin, 4 μg/ml amphotericin B, 16 μg/ml nalidixic acid, 4 μg/ml trimethoprim, and 4 μg/ml azlocillin) or PANTAV (PANTA plus 10 μg/ml vancomycin). Our results showed that treatment for 30 min with CPC (final concentration, 0.05%) of water concentrated by centrifugation, followed by culture on a rich medium supplemented with PANTA, significantly decreased the growth of nontarget microorganisms (the concentrations were 6.2 ± 0.4 log₁₀ CFU/liter on Middlebrook 7H11j medium and 4.2 ± 0.2 log₁₀ CFU/liter on Middlebrook 7H11j medium containing PANTA [P < 0.001]), while the effect of this procedure on NTM was not as great (the concentrations of M. chelonae on the two media were 7.0 ± 0.0 log₁₀ CFU/liter and 6.9 ± 0.0 log₁₀ CFU/liter, respectively, and the concentrations of M. avium were 9.1 ± 0.0 log₁₀ CFU/liter and 8.9 ± 0.0 log₁₀ CFU/liter, respectively). We propose that this standardized culture procedure could be used for detection of NTM in aquatic samples.It is generally accepted that environmental exposure, particularly exposure through water, is the main source of most human infections caused by nontuberculous mycobacteria (NTM). The incidence of waterborne NTM skin and soft tissue infections in immunocompetent patients is increasing (31), as is the incidence of pulmonary infections that occur due to aerosol inhalation (15, 31). Ingestion or inhalation of contaminated water (while swimming, for instance) could also be a source of NTM infections in children (31). Because NTM are emerging pathogens for humans and domestic animals, it is important to identify their environmental sources and reservoirs and to measure their proliferation and persistence in freshwater ecosystems. A robust and standardized method for environmental detection of NTM is necessary to do this.NTM are ubiquitous and can be isolated from a variety of aquatic ecosystems, including natural water, wastewater, drinking water, recreational water, and industrial water (16, 51). Even hospital water has been reported to be contaminated by NTM (31). More precisely, aquatic plants, amoebae, and aquatic vertebrates and invertebrates could be considered NTM reservoirs in aquatic ecosystems in natural environments and in drinking water distribution systems or buildings and homes (19, 26, 37). Once present in a system, mycobacteria may proliferate and persist (4).Typically, the methods usually used for detection of NTM are methods that are used for clinical microbiology and have not been adapted for environmental samples. Surface water samples are quite different from clinical samples, since they may contain low levels of NTM but typically contain highly diverse bacterial communities in which the concentrations of bacteria range from 10⁴ to 10⁷ cells per ml (54). This microbial diversity makes it likely that nontarget species will overgrow NTM in nutrient-rich medium. Several studies have been conducted to determine the optimum decontamination method for inhibiting the growth of nontarget bacteria in NTM assays, although most of the methods were developed for clinical samples (2, 8, 20, 42, 56). Moreover, no clear consensus for treatment of environmental samples has emerged from these studies. The combination of chemical decontamination and addition of antibiotics to culture medium has not been studied previously for water surface samples.The aim of this study was to develop and validate an improved method for detecting and counting NTM in surface water. To do this, we compared the results for recovery of mycobacteria from water samples and inactivation of nontarget microorganisms (fungi and bacteria other than mycobacteria) when various antibiotics and chemical decontaminants were used.     

Distribution and Respiratory Activity of Mycobacteria in Household Water System of Healthy Volunteers in Japan

The primary infectious source of nontuberculous mycobacteria (NTM), which are known as opportunistic pathogens, appears to be environmental exposure, and it is important to reduce the frequency of exposure from environmental sources for preventing NTM infections. In order to achieve this, the distribution and respiratory activity of NTM in the environments must be clarified. In this study, we determined the abundance of mycobacteria and respiratory active mycobacteria in the household water system of healthy volunteers using quantitative PCR and a fluorescent staining method, because household water has been considered as one of the possible infectious sources. We chose healthy volunteer households in order to lessen the effect of possible residential contamination from an infected patient. We evaluated whether each sampling site (bathroom drain, kitchen drain, bath heater pipe and showerhead) have the potential to be the sources of NTM infections. Our results indicated that drains in the bathroom and kitchen sink are the niche for Mycobacterium spp. and M. avium cells were only detected in the bathtub inlet. Both physicochemical and biologic selective pressures may affect the preferred habitat of Mycobacterium spp. Regional differences also appear to exist as demonstrated by the presence (US) or absence (Japan) of Mycobacterium spp. on showerheads. Understanding of the country specific human activities and water usage will help to elucidate the infectious source and route of nontuberculous mycobacterial disease.     

Persistence of nontuberculous mycobacteria in a drinking water system after addition of filtration treatment

There is evidence that drinking water may be a source of infections with pathogenic nontuberculous mycobacteria (NTM) in humans. One method by which NTM are believed to enter drinking water distribution systems is by their intracellular colonization of protozoa. Our goal was to determine whether we could detect a reduction in the prevalence of NTM recovered from an unfiltered surface drinking water system after the addition of ozonation and filtration treatment and to characterize NTM isolates by using molecular methods. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration and ozonation after 6 months of sampling. Sample sites included those at treatment plant effluents, distributed water, and cold water taps (point-of-use [POU] sites) in public or commercial buildings located within each distribution system. NTM were recovered from 27% of the sites. POU sites yielded the majority of NTM, with >50% recovery despite the addition of ozonation and filtration. Closely related electrophoretic groups of Mycobacterium avium were found to persist at POU sites for up to 26 months. Water collected from POU cold water outlets was persistently colonized with NTM despite the addition of ozonation and filtration to a drinking water system. This suggests that cold water POU outlets need to be considered as a potential source of chronic human exposure to NTM.     

Detection of mycobacteria in clinical specimen using the mycobacteria growth indicator tube (MGIT) and the Lowenstein Jensen medium.

The recovery rates of mycobacteria strains isolated from 1200 clinical specimens using the mycobacteria growth indicator tube (MGIT) system and the conventional Lowenstein Jensen medium (LJ) were assessed. Of the 87 mycobacterial isolates recovered, 54 belonged to the M. tuberculosis complex (MTB) and 33 to the non-tuberculosis complex (NTM). MGIT recovered 78 (89.65%) mycobacteria isolates (51 MTB (94.44%) and 27 NTM (81.81%) and LJ recovered 70 (80.46%) mycobacteria isolates (49 MTB (90.74%) and 21 NTM (63.63%). Sixty one (70.1%) of the total mycobacteria isolates were recovered with both systems (46 (85.2%) MTB and 15 (45.5%) NTM). No significant difference was found between MGIT and LJ (p > 0.05) in both MTB and NTM recoveries. The average detection time for MTB was significantly shorter with MGIT than with LJ, in both the smear-positive specimens (8 vs 30 days: p < 0.0001) and smear-negative specimens (15 vs 30 days: p < 0.001). The average detection time of NTM was also shorter for MGIT (15 vs 30 days: p < 0.0001). However, the contamination rate was higher in MGIT (8.5%) than in LJ (3%). The results suggest that the use of MGIT contributes to a more rapid and effective diagnosis of mycobacterial infections particularly when combined with the classical LJ.     

Increase in Nontuberculous Mycobacteria Isolated in Shanghai,China: Results from a Population-Based Study

Background

In China, the prevalence of nontuberculous mycobacteria (NTM) in isolates from mycobacterial culture-positive patients with pulmonary tuberculosis (TB) is largely unknown.

Methods

We used conventional biochemical and 16S rRNA gene sequencing to identify species of mycobacteria in specimens from patients suspected of having TB. Drug-susceptibility testing was performed on NTM isolates using the proportion method. We also determined the independent risk factors associated with infection with NTM compared with infection with Mycobacterium tuberculosis.

Results

The overall rate of NTM isolated from mycobacterial culture-positive patients was 5.9% in this population, with a significantly increasing trend from 3.0% in 2008 to 8.5% in 2012 (P for trend <0.001). The organism most frequently identified was M. kansasii (45.0%), followed by M. intracellulare (20.8%) and M. chelonae/abscessus (14.9%). The overall proportion of isolates resistant to the four first-line anti-TB agents were 64.6% for isoniazid, 77.6% for streptomycin, 63.3% for rifampicin and 75.1% for ethambutol. The risk factors most often associated with NTM infection were older age (P for trend <0.001), being a resident of Shanghai (adjusted odds ratio [aOR], 1.48; 95% CI, 1.10–2.00), having been treated for tuberculosis (aOR, 1.64; 95% CI, 1.18–2.29), having a cavity on chest X-ray (aOR, 1.51; 95% CI, 1.16–1.96), and being sputum smear–negative (aOR, 1.59; 95% CI, 1.16–2.18).

Conclusions

The prevalence of NTM isolated in Shanghai increased between 2008 and 2012, thus clinicians should consider NTM as a possible cause of TB-like disease. Accurate species identification is imperative so that proper treatment can be administered for diseases caused by the diversity of NTM species.     

Incidence of nontuberculous mycobacteria in four hot water systems using various types of disinfection

The objective of this study was to determine the incidence of nontuberculous mycobacteria (NTM) in hot water systems of 4 selected hospital settings. The hospitals provided the following types of disinfection for their hot water systems: hydrogen peroxide and silver, thermal disinfection, chlorine dioxide, and no treatment (control). In each building, 6 samples were collected from 5 sites during a 3 month period. NTM were detected in 56 (46.7%) of 120 samples; the CFU counts ranged from 10 to 1625 CFU/L. The detected NTM species were the pathogens Mycobacterium kansasii, Mycobacterium xenopi, and Mycobacterium fortuitum and the saprophyte Mycobacterium gordonae. The most common to be isolated was M. xenopi, which was present in 51 samples. The hot water systems differed significantly in the incidence of NTM. NTM were not detected in the system treated by thermal disinfection, and a relatively low incidence (20% positive samples) was found in the system disinfected with chlorine dioxide. However, a high incidence was found in the control system with no additional disinfection (70% positives) and in the system using hydrogen peroxide and silver (97% positives). Water temperatures above 50 degrees C significantly limited the occurrence of NTM.     

Implication of species change of Nontuberculous Mycobacteria during or after treatment

Background

Co-existence or subsequent isolation of multiple nontuberculous mycobacteria (NTM) species in same patient has been reported. However, clinical significance of these observations is unclear. The aim of this study was to determine clinical implications of changes of NTM species during or after treatment in patients with NTM lung disease.

Methods

Patients with NTM lung disease, who experienced changes of NTM species during treatment or within 2 years of treatment completion between January 1, 2009 and December 31, 2015, were included in the analysis. Demographic, clinical, microbiological, and radiographic data were reviewed and analyzed.

Results

During the study period, 473 patients were newly diagnosed with NTM lung disease. Treatment was started in 164 patients (34.6%). Among these 164 patients, 16 experienced changes of NTM species during or within 2 years of treatment completion. Seven showed changes from M. avium complex (MAC) to M. abscessus subspecies abscessus (MAA) and five patients displayed changes from M. abscessus subspecies massiliense (MAM) to MAC. With isolation of new NTM species, 6 out of 7 patients with change from MAC to MAA reported worsening of symptoms, whereas none of the five patients with change from MAM to MAC reported worsening of symptoms. All MAA isolated during or after treatment for MAC lung diseases showed inducible resistance to clarithromycin.

Conclusions

Change of NTM species may occur during or after treatment for NTM lung disease. Especially, changes from MAC to MAA is accompanied by symptomatic and radiographic worsening as well as inducible resistance to clarithromycin.