Nontuberculous Mycobacteria Isolates Research Articles

Investigation of non-tuberculous mycobacteria in a primary hospital from southeastern China.

Non-tuberculous mycobacterium (NTM) can colonize the human body, leading to opportunistic infection. This study was conducted to analyze the NTM species composition in a primary hospital and investigate the potential features of the patients with different NTM species. Mycobacterial strains were collected from the patients admitted at the hospital from January 2016 to May 2019. MPB64 assay was used to screen NTM strains and confirmed by Rv0577 amplification. The species were identified by hsp65 sequencing. The clinical records of patients with NTM were retrospectively reviewed. Among the 122 identified NTM isolates, the most common strains were Mycobacterium avium complex (MAC, n = 102, 83.6%), Mycobacterium abscessus (n = 9, 7.4%) and Mycobacterium lentiflavum (n = 5, 4.1%). The predominant species among MAC were Mycobacterium chimaera (n = 57, 46.7%), followed by Mycobacterium intracellulare (n = 25, 20.5%) and Mycobacterium colombiense (n = 17, 13.9%). A significantly lower percentage of positive acid-fast assay was observed in Mycobacterium colombiense positive patients than in those with Mycobacterium intracellulare and Mycobacterium chimaera. Mycobacterium intracellulare was more frequently isolated in patients from the infectious department than in other MAC members. A predominant prevalence of Mycobacterium chimaera in Dongyang of Zhejiang Province was different from other regions in China, indicating that its prevalence has been likely underestimated. The heterogeneity in clinical features, caused by different MAC members, required an accurate species identification of the NTM isolated in the primary hospitals.

Is there a role for tedizolid in the treatment of non-tuberculous mycobacterial disease?

BackgroundPulmonary infections caused by non-tuberculous mycobacteria (NTM) are hard to treat and have low cure rates despite intensive multidrug therapy.ObjectivesTo assess the feasibility of tedizolid, a new oxazolidinone, for the treatment of Mycobacterium avium and Mycobacterium abscessus.MethodsWe determined MICs of tedizolid for 113 isolates of NTM. Synergy with key antimycobacterial drugs was assessed using the chequerboard method and calculation of the FIC index (FICI). We performed time–kill kinetics assays of tedizolid alone and combined with amikacin for M. abscessus and with ethambutol for M. avium. Human macrophages were infected with M. abscessus and M. avium and subsequently treated with tedizolid; intracellular and extracellular cfu were quantified over time.ResultsNTM isolates generally had a lower MIC of tedizolid than of linezolid. FICIs were lowest between tedizolid and amikacin for M. abscessus (FICI = 0.75) and between tedizolid and ethambutol for M. avium (FICI = 0.72). Clarithromycin and tedizolid showed initial synergy, which was abrogated by erm(41)-induced macrolide resistance (FICI = 0.53). Tedizolid had a weak bacteriostatic effect on M. abscessus and combination with amikacin slightly prolonged its effect. Tedizolid had concentration-dependent activity against M. avium and its efficacy was enhanced by ethambutol. Both combinations had a concentration-dependent synergistic effect. Tedizolid could inhibit the intracellular bacterial population of both M. avium and M. abscessus.ConclusionsTedizolid should be further investigated in pharmacodynamic studies and clinical trials for M. avium complex pulmonary disease. It is less active against M. abscessus, but still promising.

Non-tuberculous mycobacteria in lung transplant recipients: Prevalence, risk factors, and impact on survival and chronic lung allograft dysfunction.

Non-tuberculous mycobacteria (NTM) are environmental organisms that colonize or infect lung transplant recipients. Because of differences in populations studied and geographical diversity of species, risk factors for infection and its impact on patient outcomes post transplant are conflicting in the literature. We reviewed the charts of 375 lung transplant recipients at the University of Alberta Hospital (Edmonton, Canada) between 2005 and 2014 to assess NTM epidemiology and risk factors. NTM positivity was determined from a laboratory database. The impact of NTM on patient and graft survival was tested by multivariate Cox regression analysis. Non-tuberculous mycobacteria were cultured from 26 patients before and 17 patients after transplant. The most commonly isolated species were Mycobacterium avium complex (55%) and Mycobacterium abscessus (20%). Five-year mortality was significantly higher in those infected with NTM after transplant (P=.016), but there was no difference in chronic lung allograft dysfunction (CLAD) at 5years (P=.999). Cystic fibrosis and lower body mass index were associated with pre-transplant but not post-transplant NTM. Isolation of NTM occurred in 7% of patients before and 4.5% of patients after transplant. In this cohort, NTM isolation was associated with increased risk of death but not CLAD onset at 5years.

Clusters of nontuberculous mycobacteria linked to water sources at three Veterans Affairs medical centers.

To characterize nontuberculous mycobacteria (NTM) associated with case clusters at 3 medical facilities. Retrospective cohort study using molecular typing of patient and water isolates. Veterans Affairs Medical Centers (VAMCs). Isolation and identification of NTM from clinical and water samples using culture, MALDI-TOF, and gene population sequencing to determine species and genetic relatedness. Clinical data were abstracted from electronic health records. An identical strain of Mycobacterium conceptionense was isolated from 41 patients at VA Medical Centers (VAMCs A, B, and D), and from VAMC A's ICU ice machine. Isolates were initially identified as other NTM species within the M. fortuitum clade. Sequencing analyses revealed that they were identical M. conceptionense strains. Overall, 7 patients (17%) met the criteria for pulmonary or nonpulmonary infection with NTM, and 13 of 41 (32%) were treated with effective antimicrobials regardless of infection or colonization status. Separately, a M. mucogenicum patient strain from VAMC A matched a strain isolated from a VAMC B ICU ice machine. VAMC C, in a different state, had a 4-patient cluster with Mycobacterium porcinum. Strains were identical to those isolated from sink-water samples at this facility. NTM from hospital water systems are found in hospitalized patients, often during workup for other infections, making attribution of NTM infection problematic. Variable NTM identification methods and changing taxonomy create challenges for epidemiologic investigation and linkage to environmental sources.

Optimized Method for Isolation of Nontuberculous Mycobacteria from Hospital Aquatic Sources

Optimized Method for Isolation of Nontuberculous Mycobacteria from Hospital Aquatic Sources

Pseudo-outbreak of Mycobacterium paragordonae in a hospital: possible role of the aerator/rectifier connected to the faucet of the water supply system

Pseudo-outbreaks of non-tuberculous mycobacteria (NTM) in association with the water supply system in hospitals have been previously reported. We found that the frequency of NTM isolation in clinical samples increased after the reconstruction and renovation of a hospital in Japan in 2014. To analyse NTM, their possible relationship with the hospital water supply system, and outcomes of preventive measures. Environmental samples obtained from the water supply in hospital wards were tested for NTM. On obtaining positive results, the bacteria were further analysed using polymerase chain reaction (PCR). The PCR products of NTM showed that most samples tested positive for Mycobacterium paragordonae. Because none of the analysed patients developed any disease due to these bacteria, this event was considered a pseudo-outbreak. Investigation of the water supply system revealed that samples obtained from the recently attached aerators/rectifiers during hospital renovation tested positive for these bacteria. Therefore, measures to remove aerators/rectifiers and prevent patients from drinking tap water in the hospital were introduced. Thereafter, the frequency of NTM-positive samples significantly decreased in the hospital. This study is one of the few reports which reveal the possibility of pseudo-outbreaks of M.paragordonae in hospitals, hence raising the question whether aerators/rectifiers should be used in hospitals at all, because their mesh structure may promote NTM proliferation in supplied water. The importance of surveillance of bacteria derived from the environment, particularly after hospital reconstruction/renovation, is re-emphasized.

Application of diagnostic criteria for non-tuberculous mycobacterial disease to a case series of mycobacterial-positive isolates

The American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) have provided guidelines to assist in the accurate diagnosis of lung disease caused by nontuberculous mycobacteria (NTM). These microbiologic, radiographic, and clinical criteria are considered equally important and all must be met to make the diagnosis of NTM lung disease. To assess the significance of the three criteria, each was evaluated for its contribution to the diagnosis of NTM lung disease in a case series. Laboratory reports of any specimen positive for NTM isolation were collected between January 1, 2006 and December 31, 2010 at a university medical center. Medical records were reviewed in detail using a standardized form. The total number of patients with a culture from any site positive for NTM was 297 while the number from respiratory specimens during the same period was 232 (78%). Samples from two of these patients also yielded M. tuberculosis complex and were excluded. While 128 of the remaining 230 patients (55.7%) in the cohort met the microbiologic criterion for diagnosis of NTM lung disease, 151 (65.6%) and 189 (78.3%) met the radiologic and clinical criteria respectively. Only 78 patients (33.9%) met all three criteria provided by the ATS/IDSA for diagnosis of NTM lung disease. This evaluation reaffirms that defining NTM lung disease using either one or two of the criteria provided by the 2007 ATS/IDSA guidelines may significantly overestimate the number of cases of NTM lung disease. Based on the experience of defining NTM lung disease in this case series, recommendations for modification of the ATS/IDSA guidelines are provided which include expansion of both radiologic patterns and the list of symptoms associated with NTM lung disease.

<p>Epidemiology Of Human Pulmonary Infection With Nontuberculous Mycobacteria In Southeast China: A Prospective Surveillance Study</p>

BackgroundChina is facing a great challenge of pulmonary nontuberculous mycobacteria (NTM) infections. This primary objective of this study was to assess the prevalence of NTM isolates among patients with presumptive TB in Fujian.MethodsThe mycobacterial isolates were collected from the tuberculosis survey from Fujian Province conducted between July 1, 2010 and June 30, 2011.ResultsFrom July 1, 2010 to June 30, 2011, 1425 isolates were included in the final analysis, of which 60 (4.2%) were identified as NTM species. M. intracellulare was the most frequently isolated NTM in Fujian, accounting for 68.3% of all NTM isolates. Compared with patients aged <45 years, patients aged 45–59 were more likely to have NTM infections. The education level of patients had an impact on the distribution of NTM infections. Illiterate patients had significantly higher odds of having NTM compared to literate patients. Patients with a previous TB episode had higher NTM risk as compared to those without previous TB episodes.ConclusionIn conclusion, the predominant NTM is M. intracellulare among patients with presumptive TB in Fujian. In addition, elderly patients, those with a previous TB episode and illiterate patients have higher NTM risk.

Nontuberculous mycobacteria isolated from specimens of pulmonary tuberculosis suspects, Northern Tunisia: 2002\u20132016

BackgroundReports on the worldwide ascending trend of pulmonary nontuberculous mycobacteria (NTM) isolation rates and their effective role in respiratory tract infections are compelling. However, as yet, there are no such data relating to Tunisia.MethodsHere we carried out a retrospective review of mycobacterial cultures originating from Northern Tunisia, which have been processed in the laboratory of mycobacteria of the Institut Pasteur de Tunis, during the time period 2002–2016. All pulmonary NTM (PNTM) isolates available for culture were characterized phenotypically and their taxonomic status was further established based on polymorphisms in rpoB, 16S rRNA, hsp65, and sodA DNA gene sequences.ResultsOf the 10,466 specimens collected from HIV-negative Tunisian patients with presumptive clinical pulmonary TB, 60 (0.6%) yielded PNTM isolates. An overall annual PNTM isolation prevalence of 0.2/100,000 was estimated. As far as could be ascertained, this isolation rate accounts amongst the lowest reported hitherto throughout the world. Among the 30 NTM isolates that were available for culture, 27 (90.0%) have been identified to the species level. The most commonly encountered species was Mycobacterium kansasii (23.3%) subtype 1. Strikingly, all M. kansasii cases were male patients originating from Bizerte, an industrialized region particularly known for iron industry. The remaining NTM species were M. fortuitum (16.6%), M. novocastrense (16.6%), M. chelonae (10.0%), M. gordonae (6.6%), M. gadium (6.6%), M. peregrinum (3.3%), M. porcinum (3.3%), and M. flavescens (3.3%). There were no bacteria of the M. avium complex, the most frequently isolated NTM globally, and the main driver of the rise of NTM-lung diseases.ConclusionsThis study uncovered an exceptional low prevalence of PNTM isolation among HIV-negative TB suspects in Northern Tunisia, suggesting a very low burden of NTM pulmonary disease. However, the frequent isolation of M. kansasii subtype 1, the most pathogenic subtype, particularly from the industrialized region of Bizerte, strongly suggests its effective involvement in a typical pulmonary disease.

Auranofin Activity Exposes Thioredoxin Reductase as a Viable Drug Target in Mycobacterium abscessus.

Nontuberculous mycobacteria (NTM) are highly drug-resistant, opportunistic pathogens that can cause pulmonary disease. The outcomes of the currently recommended treatment regimens are poor, especially for Mycobacterium abscessus New or repurposed drugs are direly needed. Auranofin, a gold-based antirheumatic agent, was investigated for Mycobacterium tuberculosis Here, we test auranofin against NTM in vitro and ex vivo We tested the susceptibility of 63 NTM isolates to auranofin using broth microdilution. Next, we assessed synergy between auranofin and antimycobacterial drugs using the checkerboard method and calculated the fractional inhibition concentration index (FICI). Using time-kill kinetics assays (TK), we assessed pharmacodynamics of auranofin alone and in combination with drug combinations showing the lowest FICIs for M. abscessus CIP 104536. A response surface analysis was used to assess synergistic interactions over time in TKs. Primary isolated macrophages were infected with M. abscessus and treated with auranofin. Finally, using KEGG Orthology, we looked for orthologues to auranofins drug target in M. tuberculosisM. abscessus had the lowest auranofin MIC50 (2 μg/ml) among the tested NTM. The lowest average FICIs were observed between auranofin and amikacin (0.45) and linezolid (0.50). Auranofin exhibited concentration-dependent killing of M. abscessus, with >1-log killing at concentrations of >2× MIC. Only amikacin was synergistic with auranofin according to Bliss independence. Auranofin could not lower the intracellular bacterial load in macrophages. Auranofin itself may not be feasible for M. abscessus treatment, but these data point toward a promising, unutilized drug target.

Isolation and identification of Nontuberculous mycobacteria from environmental water samples in the northeast of Iran

Isolation and identification of Nontuberculous mycobacteria from environmental water samples in the northeast of Iran

Bacteriological quality of bottled water obtained from Mexico City small water purification plants: Incidence and identification of potentially pathogenic nontuberculous mycobacteria species

The aim of this study was to determine the bacteriological quality of bottled water samples obtained from small purification plants located in Mexico City and to identify potentially pathogenic nontuberculous mycobacteria (NTM) species found in these samples. All 111 samples analyzed were positive for aerobic mesophilic bacteria (AMB) and 46 (41.4%) did not comply with Mexico's Official Guidelines. Sixty-nine (62.1%) and 23 (20.7%) water samples were positive for total coliforms (TC) and fecal coliforms (FC), respectively. A total of 81 (72.9%) of the water samples exceeded the maximum allowed limit stipulated in the guideline. Thirty-three (29.7%) of the purified water samples were positive for NTM, being recovered a total of 40 isolates. These NTM isolates were identified using three molecular markers (hsp65, rrs and rpoB genes) which corresponded to the fast-growing mycobacteria M. chelonae (n = 12), M. porcinum (n = 8), M. senegalense (n = 5), M. abscessus (n = 4), M. septicum (n = 4), M. wolinskyi (n = 3), M. mucogenicum (n = 2), M. fortuitum (n = 1) and M. sp. (n = 1). In seven purified water samples, two different NTM species were isolated simultaneously. Overall, these results showed that most of the purified bottled water samples analyzed in this study had unsatisfactory microbiological quality and some harbored NTM associated with illness. Our data could hasten health authorities to intensify efforts in the routine monitoring of activities in the purified bottled water industry in order to supply safe and healthy water to the public.

The Incidence of Non-Tuberculous Mycobacteria in Infants in Kenya.

There is inadequate understanding of the epidemiology of Non-Tuberculous Mycobacteria (NTM) among infants in high tuberculosis burden countries. The objective of this study was to document the incidence and diversity of NTM disease or colonisation in sputum specimens from infants with presumptive TB, the risk factors, and clinical characteristics, in a high TB and HIV burden setting in Western Kenya. A cohort of 2900 newborns was followed for 1–2 years to assess TB incidence. TB investigations included collection of induced sputa and gastric aspirates for culture and speciation by HAIN®, Tuberculin Skin Testing (TST), HIV testing, and chest radiography. The American Thoracic Society Criteria (ATS) were applied to identify NTM disease. Among 927 (32% of 2900) with presumptive TB, 742 (80%) were investigated. NTM were isolated from 19/742 (2.6%) infants. M. fortuitum was most frequently speciated (32%). Total person-time was 3330 years. NTM incidence was 5.7/1,000 person-years, 95% CI (3.5, 8.7). Infants diagnosed with TB were more likely to have NTM isolation (odds ratio 11.5; 95% CI 3.25, 41.0). None of the infants with NTM isolated met the criteria for NTM disease. The incidence of NTM isolation was comparable to similar studies in Africa. NTM isolation did not meet ATS criteria for disease and could represent colonisation. TB disease appears to be structural lung disease predisposing to NTM colonisation.

Evaluating the clinical significance of nontuberculous mycobacteria isolated from respiratory samples in Iran: an often overlooked disease.

PurposeNontuberculous mycobacteria (NTM) infection is an increasing problem worldwide whose clinical significance is still largely unknown. The aim of this study was to investigate the epidemiology of NTM infection from respiratory samples and to determine their clinical significance.Patients and methodsThis cross-sectional study was performed on 7,825 clinical samples from December 2015 to December 2017. Detection was conducted using phenotypic and genotypic (hsp65 PCR-RFLP, rpoB, and 16S rRNA genes sequencing) methods. All clinical information including symptoms and radiological findings was extracted from patients’ records.ResultsA total of 478 were confirmed to have respiratory samples which were culture positive for mycobacteria, with the prevalence of NTM infection obtained as 53 (11.1%). Overall, Mycobacterium (M.) fortuitum was the most frequent NTM isolate, followed by M. simiae, M. kansasii, M. gordonae, and M. conceptionense. There was a relationship between NTM isolates and gender (P=0.039), symptoms (P=0.048), and radiographic findings (P=0.013). Bronchiectasis, infiltration, and cavitary lesion were the most frequent radiological findings in M. fortuitum, M. simiae, and M. kansasii, respectively, with cough being the most frequent symptom.ConclusionWe reported five different NTM isolates in respiratory samples with a high frequency of M. fortuitum. NTM infections may play an important role in causing pulmonary disease and in tuberculosis management in endemic settings. Nevertheless, more studies are required to further examine the clinical significance of NTM isolates.

Prevalence of non-tuberculous mycobacteria in HIV-infected patients admitted to hospital with pneumonia.

<sec id="st1"> <title>BACKGROUND</title> People living with the human immunodeficiency virus (PLWH) may be particularly vulnerable to the consequences of non-tuberculous mycobacteria (NTM) given their defective T cell-mediated immunity and high rates of structural lung disease. </sec> <sec id="st2"> <title>OBJECTIVE</title> To determine the prevalence of NTM in PLWH hospitalized with pneumonia and to assess the potential predictors of NTM isolation. </sec> <sec id="st3"> <title>METHODS</title> Secondary data analysis of a prospective cohort study (2007-2011) of early bronchoscopy in PLWH presenting with suspected pneumonia was undertaken. Subjects with any species of NTM, henceforth described as 'NTM of undetermined significance' (NTM-US), isolated from sputum or bronchoalveolar lavage fluid (BALF), were included in the analysis. Potential predictors were chosen a priori. </sec> <sec id="st4"> <title>RESULTS</title> Among 196 HIV-infected subjects hospitalized with pneumonia, 96 had respiratory samples positive for NTM-US, with 91% of all NTM-US isolated from sputum compared with BALF. The overall prevalence of NTM-US was 49% (96/196). More NTM subjects were smokers (P = 0.08), with a history of chronic obstructive pulmonary disease (P = 0.08). Among those with pathogenic NTM, 39% (34/88) would have met American Thoracic Society microbiologic criteria for NTM pulmonary disease (17% of total cohort). </sec> <sec id="st5"> <title>CONCLUSIONS</title> Respiratory cultures, predominantly sputum samples, were positive for NTM-US in 45% of HIV-infected subjects admitted to hospital for pneumonia. Further research is needed to characterize the prevalence of NTM in PLWH and help establish specific diagnostic criteria in this population. </sec>.

Non-Tuberculous Mycobacteria: Seven-Year Experience of a Tertiary Hospital.

Non-tuberculous mycobacteria are ubiquitous organisms. Precise determination of infection numbers is difficult, sincereporting them to public health departments is frequently not mandatory; furthermore, isolating a non-tuberculous mycobacteria doesnot necessarily translate into disease. The aims of this study were to ascertain non-tuberculous mycobacteria data of a tertiary hospital,determine the incidence and approach to colonization versus disease, and the incidence of predisposing comorbidities. Retrospective study in a tertiary hospital, involving patients with positive cultural exam for non-tuberculousmycobacteria in any biological sample, from 2010 to 2017. A total of 125 non-tuberculous mycobacteria isolates was identified, corresponding to 96 patients. Of these, 57.4% were male(n = 54); median age was 65 years (interquartile range = [50 - 82]). From these, 60.7% (n = 57) had some degree of immunosuppression,most frequently due to malignant tumour (49.0%) or HIV infection (39.2%). It was found that 29 patients (31.0%) had structuralrespiratory tract changes. Colonization was defined in 65.6% of patients (n = 63). While 71.0% of non-tuberculous mycobacteria infectionswere pulmonary, the remaining 29.0% presented as disseminated. According to available clinical records, 60.6% (n = 20) of thepresumably infected patients fulfilled American Thoracic Society diagnostic criteria for non-tuberculous mycobacteria disease. Several cases of non-tuberculous mycobacteria infection in this study presented as life-threatening, multi-systemic disease,highlighting the importance of accurate diagnosis and timely treatment. Other cases of presumed infection might instead havecorresponded to colonization, possibly resulting in futile therapy. While there are diagnostic criteria for treatment of non-tuberculous mycobacteria infections, no such guidelines existto assess colonization. One of the most challenging aspects remains the correct differentiation between colonization and early-stageinfection.

A clinical prediction model for hospitalized COPD exacerbations based on "treatable traits".

BackgroundAssessing risk of future exacerbations is an important component in COPD management. History of exacerbation is a strong and independent predictor of future exacerbations, and the criterion of ≥2 nonhospitalized or ≥1 hospitalized exacerbation is often used to identify high-risk patients in whom therapy should be intensified. However, other factors or “treatable traits” also contribute to risk of exacerbation.ObjectiveThe objective of the study was to develop and externally validate a novel clinical prediction model for risk of hospitalized COPD exacerbations based on both exacerbation history and treatable traits.Patients and methodsA total of 237 patients from the COPD Registry of Changi General Hospital, Singapore, aged 75±9 years and with mean post-bronchodilator FEV1 60%±20% predicted, formed the derivation cohort. Hospitalized exacerbation rate was modeled using zero-inflated negative binomial regression. Calibration was assessed by graphically comparing the agreement between predicted and observed annual hospitalized exacerbation rates. Predictive (discriminative) accuracy of the model for identifying high-risk patients (defined as experiencing ≥1 hospitalized exacerbations) was assessed with area under the curve (AUC) and receiver operating characteristics analyses, and compared to other existing risk indices. We externally validated the prediction model using a multicenter dataset comprising 419 COPD patients.ResultsThe final model included hospitalized exacerbation rate in the previous year, history of acute invasive/noninvasive ventilation, coronary artery disease, bronchiectasis, and sputum nontuberculous mycobacteria isolation. There was excellent agreement between predicted and observed annual hospitalized exacerbation rates. AUC was 0.789 indicating good discriminative accuracy, and was significantly higher than the AUC of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) risk assessment criterion (history of ≥1 hospitalized exacerbation in the previous year) and the age, dyspnea, and obstruction index. When applied to the independent multicenter validation cohort, the model was well-calibrated and discrimination was good.ConclusionWe have derived and externally validated a novel risk prediction model for COPD hospitalizations which outperforms several other risk indices. Our model incorporates several treatable traits which can be targeted for intervention to reduce risk of future hospitalized exacerbations.

Species distribution characteristics of nontuberculous mycobacteria isolated from patients with acquired immunodeficiency syndrome in Shanghai

Objective To investigate the species distribution characteristics of nontuberculous mycobacteria (NTM) in acquired immunodeficiency syndrome(AIDS) patients in Shanghai, and to provide evidences for clinical treatment. Methods A total of 775 Mycobacteria strains were isolated from patients (including 129 isolates from AIDS patients and 646 isolates from HIV-negative patients) admitted to Shanghai Public Health Clinical Center during 2015. All the species were identified by the sequence analysis of 16S rRNA gene and hsp65 gene. Differences in the species distribution were compared between patients with and without HIV infection. CD4+ T lymphocyte count was detected by flow cytometry and its relation with mycobacteria infection was also analyzed. Chi-square test was used for comparison between groups. Results The ratio of NTM isolation from HIV-negative patients was 15.79% (102/646), while that was 46.51% in AIDS patients (60/129), and the difference was statistically significant (χ2=61.38, P 50 cells/μL (20.00% and 15.38%, respectively) (χ2=4.048 and 6.524, respectively, both P 50 cells/μL. Conclusions The prevalence of NTM isolation is significant higher in AIDS patients than HIV-negative patients in Shanghai, and the most prevalent NTM species is MAC. The NTM infection in AIDS patients is related with low CD4+ T lymphocyte counts. Key words: Acquired immunodeficiency syndrome; Nontuberculous mycobacteria; Species identification

Clinical relevance of non-tuberculous mycobacteria isolated from respiratory specimens: seven year experience in a UK hospital

The frequency of isolation of non-tuberculous mycobacteria (NTM) species from respiratory specimens is increasing, however the clinical relevance of such identifications vary by mycobacterial species and geographical location. A retrospective study of 853 NTM isolates from respiratory samples from 386 patients over seven years was performed. Clinical records and radiographic information were examined. Clinical significance was assessed by American Thoracic Society diagnostic criteria. 25% of all patients with respiratory isolates met criteria for non-tuberculous mycobacterial pulmonary disease (NTM-PD). Significant symptoms were weight loss, fever, night sweats, productive cough and haemoptysis. HIV co-infection was a significant risk factor for disease. Cavities, nodules and tree-in-bud were significant radiographic findings. Mycobacterium avium complex (MAC) were the dominant species isolated from this patient cohort. Mycobacterium abscessus (M. abscessus) was the species most likely to cause clinically significant disease and be sputum smear positive, thus warranting particular attention.

Molecular characterization of nontuberculous mycobacteria in hospital waters: a two-year surveillance study in Tehran, Iran.

Microbiological control of hospital waters as one of the main sources of nontuberculous mycobacteria (NTM) is important for the prevention of NTM-associated illness. This study aimed to investigate the prevalence of NTM in the hospital water systems of Tehran, Iran. A total of 218 samples from different hospital waters (i.e., tap water and medical devices such as humidifying cup of oxygen manometer, dialysis devices, nebulizers, and dental units) were included in this study. Phenotypic and molecular tests were used to identify the isolated organisms to species level. Of 218, 85 (39.0%) samples at 37 °C and 87 (40.0%) samples at 25 °C were identified as NTM. Using hsp65-sequencing method, Mycobacterium lentiflavum was the most frequently encountered, followed by M. gordonae and M. paragordonae. No significant difference was seen in frequency and species in mycobacteria isolated at 37 °C and 25 °C temperatures. Humidifying cup of oxygen manometer had the most contaminated water among the investigated water distribution systems in hospitals. Isolation of NTM from hospital water sources is a serious public health problem in Iran and merits further attention by health authorities. Establishment of microbiological monitoring systems for hospital waters and expanding the number of facilitated laboratories are strongly recommended.