Prevalence Of Nontuberculous Mycobacteria Research Articles

Prevalence of non-tuberculous mycobacteria (NTM) in pediatric patients with cystic fibrosis (CF) in Florida – A two center study

Prevalence of non-tuberculous mycobacteria (NTM) in pediatric patients with cystic fibrosis (CF) in Florida – A two center study

Prevalence of Nontuberculous Mycobacteria in Cystic Fibrosis Clinics, United Kingdom, 2009

Incidence of pulmonary infection with nontuberculous mycobacteria (NTM) is increasing among persons with cystic fibrosis (CF). We assessed prevalence and management in CF centers in the United Kingdom and found 5.0% of 3,805 adults and 3.3% of 3,317 children had recently been diagnosed with NTM. Of those, 44% of adults and 47% of children received treatment.

Prevalence of Nontuberculous Mycobacteria in Cystic Fibrosis Clinics, United Kingdom, 2009

Incidence of pulmonary infection with nontuberculous mycobacteria (NTM) is increasing among persons with cystic fibrosis (CF). We assessed prevalence and management in CF centers in the United Kingdom and found 5.0% of 3,805 adults and 3.3% of 3,317 children had recently been diagnosed with NTM. Of those, 44% of adults and 47% of children received treatment.

Non-tuberculous Mycobacteria in Wild Boar (Sus scrofa) from Southern Spain: Epidemiological, Clinical and Diagnostic Concerns

Non-tuberculous mycobacteria (NTM) are widely distributed in the environment, particularly in wet soil, marshland, rivers or streams, but also are causative agents of a wide variety of infections in animals and humans. Little information is available regarding the NTM prevalence in wildlife and their effects or significance in the bovine tuberculosis (bTB) epidemiology and diagnosis. This research shows the most frequently NTM isolated in lymph nodes of wild boar (Sus scrofa) from southern Spain, relating the NTM presence with the individual characteristics, the management of animals and the possible misdiagnosis of Mycobacterium bovis in concurrent infections. A total of 219 NTM isolates were obtained from 1249 wild boar mandibular lymph nodes sampled between 2007 and 2011. All but 75 isolates were identified by the PCR-restriction analysis-hsp65, and a partial sequencing of the 16S rDNA was carried out to identify the rest of the isolates. Results showed that Mycobacterium chelonae was the most frequently isolated NTM specie (133 isolates, 60.7%), followed by Mycobacterium avium (24 isolates, 11%). No relation was found regarding sex, body condition and management, but M.chelonae was more frequently detected in adults, whereas M.avium was more prevalent in subadults. The high NTM prevalence observed in the studied wild boar populations could make difficult the bTB diagnostic.

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.

Species and genotypic diversity of non-tuberculous mycobacteria isolated from children investigated for pulmonary tuberculosis in rural Uganda

BackgroundSmear microscopy, a mainstay of tuberculosis (TB) diagnosis in developing countries, cannot differentiate M. tuberculosis complex from NTM infection, while pulmonary TB shares clinical signs with NTM disease, causing clinical and diagnostic dilemmas. This study used molecular assays to identify species and assess genotypic diversity of non-tuberculous mycobacteria (NTM) isolates from children investigated for pulmonary tuberculosis at a demographic surveillance site in rural eastern Uganda.MethodsChildren were investigated for pulmonary tuberculosis as part of a TB vaccine surveillance program (2009–2011). Two cohorts of 2500 BCG vaccinated infants and 7000 adolescents (12–18 years) were recruited and followed up for one to two years to determine incidence of tuberculosis. Induced sputum and gastric aspirates were processed by the standard N-acetyl L-cysteine (NALC)-NaOH method. Sediments were cultured in the automated MGIT (Becton Dickson) liquid culture system and incubated at 37°C for at least six weeks. Capilia TB assay was used to classify mycobacteria into MTC and NTM. The GenoType CM/AS assays were performed to identify species while Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR genotyping was used to assess genetic diversity of the strains within each species.ResultsAmong 2859 infants and 2988 adolescents screened, the numbers of TB suspects were 710 and 1490 infants and adolescents respectively. The prevalence of NTM in infant suspects was 3.7% (26/710) (95% CI 2.5–5.2) while that in adolescent suspects was 4.6% (69/1490) (95% CI 3.6–5.8). On culture, 127 isolates were obtained, 103 of which were confirmed as mycobacteria comprising of 95 NTM and eight M. tuberculosis complex. The Genotype CM/AS assay identified 63 of the 95 NTM isolates while 32 remained un-identified. The identified NTM species were M. fortuitum (40 isolates, 63.5%), M. szulgai (9 isolates, 14.3%), M. gordonae (6 isolates, 9.5%), M. intracellulare (3 isolates, 4.7%), M. scrofulaceum (2 isolates, 3.2%), M. lentiflavum (2 isolates, 3.2%), and M. peregrinum (1 isolate, 1.6%). Genotyping did not reveal any clustering in M. intracellulare, M. gordonae and M. szulgai species. M. fortuitum, on the other hand, had two clusters, one with three isolates of M. fortuitum 1 and the other with two isolates of M. fortuitum 2 subspecies. The remaining 35 of the 40 isolates of M. fortuitum had unique fingerprint patterns.ConclusionM. fortuitum is the most common cause of infection by NTM among Infants and adolescents in rural Uganda. There is a varied number of species and genotypes, with minimal clustering within species, suggesting ubiquitous sources of infection to individuals in this community.

Fluorescein diacetate vital staining allows earlier diagnosis of rifampicin-resistant tuberculosis

Damien Foundation Project, Bangladesh. To evaluate sputum smear fluorescein diacetate (FDA) vital staining to predict culture-defined failure and rifampicin (RMP) resistance. A retrospective, operational study. A total of 1633 episodes of auramine smear-defined late conversion and failure could be evaluated (respectively 640 and 584 on first treatment and 185 and 224 on retreatment). Negative FDA was 95% predictive of negative culture in patients on first treatment, while its positive predictive value was around 95% during retreatment. The predictive value of a positive (not scanty) result for RMP resistance or environmental non-tuberculous mycobacteria (NTM) was at least 90%, except in late converters on first-line treatment; a negative result was over 95% exclusive of the same except in retreatment failures. FDA correctly identified 88-98% of all RMP resistance. FDA staining increased the proportion of tuberculosis patients put on second-line treatment without receiving the standard first-line retreatment regimen. In our setting, with excellent microscopy, late case presentation and low resistance prevalence, it proved indispensable for efficient culture and referrals of early suspects for rapid drug susceptibility testing (DST). In other settings with low prevalence of NTM and difficult access to accurate and rapid DST, FDA-positive failures might even be considered for immediate start of second-line treatment.

Prevalence of Nontuberculous Mycobacteria Infection, China, 2004–2009

To the Editor: Pulmonary nontuberculous mycobacteria (NTM) diseases share clinical signs with tuberculosis (TB), causing a clinical dilemma with regard to therapy for patients with these diseases (1). In the past 30 years (post-AIDS era), NTM have increasingly been associated with pulmonary diseases in humans (2). Recent studies in urban areas of the People’s Republic of China have shown that the prevalence of NTM (isolation rate of NTM among all mycobacteria) is increasing; for example, prevalence in Shanghai increased from 4.26% in 2005 to 6.38% in 2008 (3). To investigate NTM prevalence in rural areas of China, we evaluated the NTM isolation rates, species distribution, and drug-resistance profiles through a population-based TB sentinel surveillance study in Shandong Province, the second largest province in China. The study protocol was approved by the Institutional Review Board of Shandong Provincial Chest Hospital (Jinan, Shandong, China). Clinical samples were collected through the ongoing sentinel TB surveillance project, which first began in 7 counties in Shandong Province in 2004 and expanded to 13 counties in 2008. Of the total surveillance population, rural populations accounted for ≈80%. Each sample collected in this study was identified only by a unique participant number. Each surveillance site sent sputum samples from all patients with suspected TB to the TB Reference Laboratory of Shandong Provincial Chest Hospital for mycobacterial culture, drug-susceptibility testing, and species identification. From January 1, 2004, through December 31, 2009, Mycobacteria spp. were isolated from sputum specimens from 3,949 patients with suspected pulmonary TB. Of these patients, mean age ± SD was 48.7 ± 20.4 years (range 1–92 years), 74.6% were male, and 300 were being re-treated for TB. Identification of Mycobacteria spp. was first conducted by conventional biochemical testing—p-nitrobenzoic acid and 2-thiophene carboxylic acid hydrazide testing—following a standard protocol (4). Mycobacteria spp. were further identified by 16S rRNA gene sequence analysis (MicroSeq ID Microbial Indentification Software, version 2.0; Applied Biosystems, Foster City, CA, USA) to the species level as described (5). Drug-susceptibility testing was performed according to standard procedures recommended by the World Health Organization, and quality control was conducted by inter-laboratory confirmation testing by reference laboratories recognized by the World Health Organization in South Korea and in Hong Kong Special Administrative Region, China (6,7). The drug panel included 4 first-line anti-TB drugs: isoniazid, rifampin, streptomycin, and ethambutol. The conventional biochemical testing of the 3,949 Mycobacteria spp. strains identified 68 NTM strains, among which the 16s rRNA gene sequence analysis confirmed 64 (1.6%) NTM strains and identified 3 M. tuberculosis complex strains and 1 Nocardia glanders strain. Among the 64 NTM strains, 52 (81.2%) were M. intracellulare, 5 (7.8%) were M. kansasii, 3 (4.7%) were M. fortuitum, 2 (3.1%) were M. chelonae, 1 (1.6%) was M. gordonae, and 1 (1.6%) was M. scrofulaceum. The first-line anti-TB drug resistance rates of the 64 NTM strains were 100% for isoniazid, 98.4% for streptomycin, 78.1% for rifampin, and 51.6% for ethambutol (Table). Among the 3,949 Mycobacteria spp. strains, 163 (4.1%) were resistant to at least isoniazid and rifampin, of which 50 (30.7%) strains were identified as NTM. Among 300 TB re-treatment cases, 12 (4.0%) were caused by clinically significant NTM infections. Over the 6 study years, NTM isolation rates among the study population did not show a substantial increasing or decreasing trend. Table Species and drug-resistance profiles of 64 nontuberculous mycobacteria strains, Shandong Province, People’s Republic of China, 2004–2009 Our data suggest that the NTM isolation rate among patients with suspected pulmonary TB in rural China (1.6%) is relatively lower and more stable than that for urban areas (mean rate 5.09% in Shanghai) and that the Mycobacterium spp. differ from those in other areas of China (3,8–10). In China and most other developing countries to which TB is endemic, the decision to initiate pulmonary TB treatment is based only on finding a positive sputum smear by microscopy examination, not on Mycobacteria culture, species identification, and drug-resistance testing results. Among our study population, NTM strains showed high drug resistance to first-line anti-TB drugs and accounted for 30.7% of suspected multidrug-resistant TB (MDR-TB) cases and 4.0% of TB re-treatment cases. These findings suggest that pulmonary NTM infections pose substantial difficulties with regard to clinical management of NTM and MDR-TB diseases in China. Laboratory species identification is imperative before proper treatment can be determined for patients with MDR-TB. Compared with conventional biochemical testing, 16S rRNA gene sequencing analysis can more accurately identify Mycobacteria spp.

Non-tuberculous mycobacteria isolated from slaughter pigs in Mubende district, Uganda.

BackgroundThe importance of infections caused by non-tuberculous mycobacteria (NTM) in animals and humans has gained considerable recognition during the past few years. In the developed world, where pig production is extensively practiced, studies on mycobacterial infections and related control strategies have received increasing attention. The infections are reported to be caused by a wide spectrum of NTM. Unfortunately, these infections have been less recognized in sub-Saharan Africa owing to lack of awareness and systematic studies. In this study we aimed at isolating and identifying species of mycobacteria involved in causing infections in slaughter pigs in Mubende district of Uganda. Furthermore we wanted to identify factors associated with infection prevalence in the study area.MethodsA total of 363 lymph nodes were collected and cultured for the presence of mycobacteria. Isolates were identified by 16S rDNA gene sequencing. A questionnaire survey was administered to identify production related factors associated with infection prevalence. Data were assembled and analysed using descriptive statistics and mixed effects logistic regression analysis.ResultsMycobacteria were detected in 39 % (143/363) of the examined lymph nodes, 63 % (59/93) of lymph nodes with gross lesions typical of mycobacteriosis and 31% (84/270) of lymph nodes with no visible lesions. Nineteen per cent of the isolated mycobacteria were identified as Mycobacterium (M) avium, of these 78% and 22% were M. avium sub sp. Hominissuis and avium respectively. Other mycobacterial species included M. senuense (16%), M. terrae (7%) and M. asiaticum (6%). This study found free range systems (OR = 3.0; P = 0.034) and use of water from valley dams (OR = 2.0; P = 0.049) as factors associated with high prevalence of mycobacteria in slaughter pigs.ConclusionsThis study demonstrated a high prevalence of NTM infections among slaughter pigs in Mubende district of Uganda. M. avium was the most prevalent of all NTM isolated and identified. Free range system of pig management and valley dam water were the most significant factors associated with NTM prevalence in Mubende district. These findings could be of a major public health concern given that it is in a predominantly pork consuming population with 18% HIV/AIDS prevalence. Therefore, stringent post-mortem inspection at the slaughter houses is of paramount importance to reduce human exposure.

Isolation Prevalence of Pulmonary Nontuberculous Mycobacteria in Ontario in 2007

The reported prevalence of pulmonary nontuberculous mycobacteria (NTM) infections is increasing. To determine the 'isolation prevalence' of NTM in 2007 and compare it with previously published research that examined the increasing rates of isolation of NTM from clinical pulmonary specimens between 1997 and 2003. Isolation prevalence was investigated retrospectively by reviewing a cohort of all positive pulmonary NTM culture results from the Tuberculosis and Mycobacteriology Laboratory, Public Health Laboratory (Toronto, Ontario) in 2007, which identifies at least 95% of NTM isolates in Ontario. Isolation prevalence was calculated as the number of persons with a pulmonary isolate in a calendar year divided by the contemporary population and expressed per 100,000 population. Changes in isolation prevalence from previous years were assessed for statistical significance using generalized linear models with a negative binomial distribution. In 2007, 4160 pulmonary isolates of NTM were collected from 2463 patients. The isolation prevalence of all species (excluding Mycobacterium gordonae) was 19 per 100,000 population in 2007 - an increase from previous observations reported for Ontario - corresponding to an average annual increase of 8.5% from 1997 to 2007 (P<0.0001). Average annual increases in isolation prevalence of Mycobacterium avium complex (8.8%, P<0.0001) and Mycobacterium xenopi (7.3%, P=0.0005) were largely responsible for the overall increase, while prevalence rates of rapidly growing mycobacteria remained relatively stable. The isolation prevalence of pulmonary NTM continues to increase significantly in Ontario, supporting the belief that pulmonary NTM disease is increasingly common.

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 microg/ml amphotericin B, 16 microg/ml nalidixic acid, 4 microg/ml trimethoprim, and 4 microg/ml azlocillin) or PANTAV (PANTA plus 10 microg/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 log(10) CFU/liter on Middlebrook 7H11j medium and 4.2 +/- 0.2 log(10) 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 log(10) CFU/liter and 6.9 +/- 0.0 log(10) CFU/liter, respectively, and the concentrations of M. avium were 9.1 +/- 0.0 log(10) CFU/liter and 8.9 +/- 0.0 log(10) CFU/liter, respectively). We propose that this standardized culture procedure could be used for detection of NTM in aquatic samples.

Multicenter Study of Prevalence of Nontuberculous Mycobacteria in Patients with Cystic Fibrosis in France

We performed a multicenter prevalence study of nontuberculous mycobacteria (NTM) involving 1,582 patients (mean age, 18.9 years; male/female ratio, 1.06) with cystic fibrosis in France. The overall NTM prevalence (percentage of patients with at least one positive culture) was 6.6% (104/1,582 patients), with prevalences ranging from 3.7% (in the east of France) to 9.6% (in the greater Paris area). Mycobacterium abscessus complex (MABSC; 50 patients) and Mycobacterium avium complex (MAC; 23 patients) species were the most common NTM, and the only ones associated with fulfillment of the American Thoracic Society bacteriological criteria for NTM lung disease. The "new" species, Mycobacterium bolletii and Mycobacterium massiliense, accounted for 40% of MABSC isolates. MABSC species were isolated at all ages, with a prevalence peak between 11 and 15 years of age (5.8%), while MAC species reached their highest prevalence value among patients over 25 years of age (2.2%).

Non‐tuberculous mycobacteria in children with cystic fibrosis: Isolation, prevalence, and predictors

Screening for non-tuberculous mycobacteria (NTM) is recommended for adults with cystic fibrosis (CF). The relevance of this organism in North American pediatric CF patients is unclear as there is limited NTM prevalence data for children. We aimed to determine the prevalence of NTM in children with CF from a single expectorated sputum and identify clinical predictors of NTM isolation. Additionally, we compared two different sputum decontamination methods before mycobacterial culture. From March to November 2004, all sputum-producing patients aged 6-18 years attending the CF clinic at the Hospital for Sick Children in Toronto, Canada, were screened for NTM. Sputum samples were processed by both a single (N-acetyl-l-cysteine + NaOH) and double (N-acetyl-l-cysteine + NaOH + oxalic Acid) decontamination method. Using our CF clinic database and patient charts we analyzed differences in FEV(1), age, sex, pancreatic sufficiency, body mass index, bacterial colonization, and antibiotic use between NTM positive and negative patients. Of 98 study patients, 6 (6.1%) were positive for NTM, 2 with Mycobacterium abscessus, and 4 with Mycobacterium avium complex. One patient with M. abscessus had clinically significant lung disease requiring treatment. We found no predictors of NTM isolation. The double decontamination method allowed detection of only half (3/6) of the positive NTM cultures. As the NTM prevalence rate in children with CF is within the range previously reported in adults and there are no reliable clinical predictors for isolation, annual sputum screening is needed to identify NTM in children. Further research is needed to determine the best sputum decontamination method for NTM culture in pediatric patients.

Clinical significance of isolation of nontuberculous mycobacteria in pulmonary tuberculosis patients

Clinical significance of isolation of nontuberculous mycobacteria (NTM) from respiratory specimens in patients with pulmonary tuberculosis is unknown. This study aimed to investigate the prevalence and clinical impact of NTM in pulmonary tuberculosis patients. We retrospectively reviewed data of patients with culture-confirmed pulmonary tuberculosis from 2000 to 2006. Those in whom NTM were isolated from respiratory specimens collected within two months before and nine months after the index culture of tuberculosis was plated were compared with those without NTM. Patients were followed for one year after initiation of anti-tuberculous treatment. Among 2133 patients with pulmonary tuberculosis, 48 (2.3%) with multiple and 106 (5.0%) with one isolate(s) of NTM were identified. Another 144 without NTM were selected and compared. The one-year mortality rates were similar among three groups. Patients with multiple NTM isolates were more likely to be symptomatic, sought medical help earlier, had smear-positive respiratory specimens, and received anti-tuberculous treatment later than those with single/no isolate(s). Cavities were more commonly visualized radiographically in patients with multiple/single NTM isolate(s) than those without NTM isolates. The mean duration of anti-tuberculous treatment was 8.8 months for patients with multiple NTM isolates, significantly longer than that in patients with single (7.6 months) and no NTM isolate(s) (7.5 months). NTM were present in the respiratory tract of 7.3% of patients with pulmonary tuberculosis. Although the outcomes were similar, the presence of NTM was associated with different clinical manifestations and had a significant impact on the treatment of tuberculosis.

Thoracoscopic management for bronchiectasis with non-tuberculous mycobacterial infection

Non-tuberculous mycobacteria (NTM) have emerged as important opportunistic pathogens of the human being in recent years. Patients with pre-existing bronchiectasis are susceptible to NTM. However, information about its occurrence among bronchiectatic patients in Shenzhen, China is lacking and its impact on the course of bronchiectasis following surgical intervention is unknown. This preliminary study aimed to investigate the prevalence of NTM in bronchiectasis that required surgery in our center, evaluate the role of intraoperative routine screening for NTM, and summarize our initial experience in thoracoscopic management for bronchiectatic patients with NTM. A retrospective analysis of clinical, microbiological data of our bronchiectatic patients with NTM over 5 years was made and 40 patients with bronchiectasis were studied to determine the role of intraoperative routine screening for NTM. The prevalence of NTM in this population of patients with bronchiectasis in our center was 6.7% (7/105). The diagnostic yield of the 40 intraoperative specimens was 7.5% (3/40). Of the 7 patients with bronchiectasis and NTM, 3 patients developed postoperative wound infections. All were cured with chemotherapy for 8 - 12 months along with vigorous surgical debridement. Another patient had a slow growth of mycobacteria involving double lungs and the right thoracic cavity and recovered after chemotherapy for nearly 14 months and tube drainage. The affected tissue was completely resected in the remaining 3 patients with no operative mortality and postoperative morbidity, and routine intraoperative screening for NTM was initiated in these patients. NTM is not uncommon in bronchiectatic patients which deserves surgeons' utmost attention. Routine intraoperative screening for NTM identified otherwise unsuspected patients has shown favorable outcomes. Thoracoscopic management for bronchiectasis with NTM is technically feasible although its role remains to be defined.

150 Prevalence of nontuberculous mycobacteria in a Czech Cystic Fibrosis centre

150 Prevalence of nontuberculous mycobacteria in a Czech Cystic Fibrosis centre

Prevalence of non-tuberculous mycobacteria in a hospital environment

In recent years, non-tuberculous mycobacteria (NTM) have emerged as an important cause of opportunistic nosocomial infections but there is little known about the isolation and identification of NTM in Korea. The aim of this study was to assess the prevalence of NTM in the hospital environment and identify the species. A total of 150 samples were collected from different parts of the hospital. NTM were isolated and identified by restriction fragment length polymorphism analysis of the gene encoding rpoB and partial sequencing analysis of hsp65 and rpoB. In this study, 60 strains of NTM were isolated from 50 of the 150 samples. Half of the tap water samples (50 of 100) were positive for mycobacteria. An estimated 73.3% of the isolates were saprophytic, 21.7% were potentially pathogenic and 5% were unidentified. The presence of NTM in hospital tap water is not uncommon. Such water isolates might cause true nosocomial infection in immunocompromised patients, in addition to the risk of false-positive culture results.

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.

Adult cystic fibrosis presenting with recurrent non-tuberculous mycobacterial infections

In November, 1997, a previously healthy 54-year-old white man presented with productive cough, low-grade fever, and chills resistant to outpatient treatment with clarithromycin and cefpodoxime proxetil. CT of the chest showed consolidation of the left lower lobe and lingula. Spirometry was normal, and HIV serology was negative. Sputum showed acid-fast bacilli (AFB) and cultures grew Mycobacterium avium intracellulare. The patient was treated with rifampicin, ethambutol hydrochloride, and clarithromycin for 2 years. In January, 2002, he presented to our clinic with recurrent symptoms. Chest CT showed only linear densities in the left lower lobe. AFB smears were again positive. Cultures grew Mycobacterium chelonae and the patient was treated with doxycycline, clarithromycin, and ciprofl oxacin. Several months later a repeat AFB smear was positive, with cultures growing Mycobacterium abcessus and M avium intracellulare. He was admitted to our unit, and highresolution chest CT showed mild bilateral central bronchiectasis. Barium swallow showed a normal swallowing mechanism without gastro-oesophageal refl ux and no laryngeal penetration. Tests for antinuclear antibody and rheumatoid factor were negative. α-1 antitrypsin and immuno globulin concentrations were normal. He was discharged 10 days after admission. Despite repeated attempts, the patient had fathered no children, therefore a sweat chloride test was done as an outpatient; the concentration was high at 96 mmol/L (normal 40–60 mmol/L). Cystic fi brosis (CF) genotyping showed that the patient was heterozygous for two diff erent CF trans membrane conductance regulator gene alleles: δF508 and R117C. The patient was treated with ciprofl axacin, clarithromycin, and ethambutol for 3 years. When last seen in March, 2006, the patient had negligible sputum production, and AFB smears have been negative since 2004. Non-tuberculous mycobacteria (NTM) are free-living organisms that are ubiquitous in the environment. Occasional isolates of NTM were generally thought to be contaminants or colonisers until the second half of the 20th century. As the prevalence of Mycobacterium tuberculosis declined in developed nations and modern microbiological methods were developed, the importance of NTM in human disease became increasingly evident. By the early 1990s, laboratories in the USA informally reported that about two-thirds of recovered mycobacteria species were NTM. Some of this increase is related to the high rate of disseminated M avium complex disease in patients with AIDS; however, there could also have been an increase in the rate of NTM infections in other groups of patients, such as those with CF. The classic description of NTM pulmonary infection is that of a patient with cavitary infi ltrates and underlying lung disease. We have seen two patients in their mid-50s, who developed recurrent NTM pulmonary infections and were sub sequently diagnosed with CF. Our second patient had congenital absence of the vas deferens and normal sweat chloride concentration; he was confi rmed to have CF by genotyping showing the δ508 and D1152H alleles. Among adults with CF, 63% are aged 18–29 years, 25% 30–39 years, 10% 40–49 years, and 2% over 50 years ; adults will represent >40% of the US cystic fi brosis population in 2005. Among the 22 301 patients in the 2000 CF Foundation registry, the diagnosis was established after the age of 17 years in only 831 (3·7%); sweat chloride tests were abnormal in 90% of cases. Although NTM infections in CF are well described, recurrent NTM infection as the initial presentation of CF has not been described. The reported prevalence of NTM in CF ranges from 3% to 30%. Contamination of mycobacterial cultures (especially by Pseudomonas aeruginosa) can lead to underestimation of the prevalence of NTM infection in CF. Controversy surrounds the distinction between NTM infection and simple colonisation in CF. Symptomatic patients with persistently positive AFB smears and new radiographic abnormalities are most likely to be truly infected. Patients with negative AFB smears but positive cultures with low numbers of colonyforming units are probably colonised. We believe our patients were actively infected and not just colonised because they were symptomatic and had repeatedly positive AFB smears, high colony-forming unit counts on culture, and new radiographic changes. Both also improved with appropriate anti-NTM therapy. Our patients were pancreatic suffi cient and their respiratory symptoms were mild and delayed in comparison to more severe CF phenotypes. They remain free of sputum colonisation by pseudomonas at age 60 years (case history presented in detail) and 57 years. We postulate that the benign course of their illness is related to the fact that they are heterozygous for two diff erent CF gene alleles, the usual δF508 and R117C/ D1152H—the latter two are associated with milder disease. We conclude that in patients with recurrent NTM infections and new radiographic abnormalities, a diagnosis of CF should be considered irrespective of the patient’s age.

Bacteriophage- based tests for the detection of Mycobacterium tuberculosis in clinical specimens: a systematic review and meta- analysis

BackgroundSputum microscopy, the most important conventional test for tuberculosis, is specific in settings with high burden of tuberculosis and low prevalence of non tuberculous mycobacteria. However, the test lacks sensitivity. Although bacteriophage-based tests for tuberculosis have shown promising results, their overall accuracy has not been systematically evaluated.MethodsWe did a systematic review and meta-analysis of published studies to evaluate the accuracy of phage-based tests for the direct detection of M. tuberculosis in clinical specimens. To identify studies, we searched Medline, EMBASE, Web of science and BIOSIS, and contacted authors, experts and test manufacturers. Thirteen studies, all based on phage amplification method, met our inclusion criteria. Overall accuracy was evaluated using forest plots, summary receiver operating (SROC) curves, and subgroup analyses.ResultsThe data suggest that phage-based assays have high specificity (range 0.83 to 1.00), but modest and variable sensitivity (range 0.21 to 0.88). The sensitivity ranged between 0.29 and 0.87 among smear-positive, and 0.13 to 0.78 among smear-negative specimens. The specificity ranged between 0.60 and 0.88 among smear-positive and 0.89 to 0.99 among smear-negative specimens. SROC analyses suggest that overall accuracy of phage-based assays is slightly higher than smear microscopy in direct head-to-head comparisons.ConclusionPhage-based assays have high specificity but lower and variable sensitivity. Their performance characteristics are similar to sputum microscopy. Phage assays cannot replace conventional diagnostic tests such as microscopy and culture at this time. Further research is required to identify methods that can enhance the sensitivity of phage-based assays without compromising the high specificity.