Activities of Linezolid against nontuberculous mycobacteria

The activity of linezolid (Pfizer, USA) was tested by broth microdilution against 53 clinical isolates of non-tuberculous mycobacteria (NTM), including the common disease producing species Mycobacterium avium, M. intracellulare, M. fortuitum, M. chelonae and M. abscessus, obtained from western Turkey. The isolates of M. abscessus and M. intracellulare were the least susceptible, M. mucogenicum, M. gordonae and M. avium were the most susceptible to linezolid of the common species of NTM. Linezolid showed a variable sensitivity in all strains; therefore, each species and strain must be individually evaluated, and it is always advisable to perform in vitro sensitivity tests before using the drug for human therapy.     

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).     

Shifting paradigms of nontuberculous mycobacteria in cystic fibrosis

Important paradigms of pulmonary disease with nontuberculous mycobacteria (NTM) are currently shifting based on an increasing attention within the field of cystic fibrosis (CF). These shifts are likely to benefit the management of all patients with pulmonary NTM, regardless of underlying pathology. Currently several key areas are being revised: The first outbreak of human NTM transmission has been proven and new evidence of biofilm growth in vivo has been demonstrated. A better understanding of the clinical impact of NTM infection has led to increased diagnostic vigilance and new recommendations for lung transplantation are under way. While recent changes have reinvigorated the interest in NTM disease, the challenge remains, whether such advances can be successfully translated into improved management and care.     

Identification of nontuberculous mycobacteria by methods of molecular biology

A number of clinical and laboratory strains of microorganisms belonging to different species of mycobacteria of the nontuberculous complex were tested with the use of the polymerase chain reaction and the restriction analysis. The unique restriction profiles of the following species of mycobacteria have been obtained: M. fortuitum VI, M. kansasii I, M. intracellulare, M. avium.     

Prevalence of nontuberculous mycobacteria in water supplies of hemodialysis centers

Infection of hemodialysis patients with nontuberculous mycobacteria (NTM) has been associated with water used in reprocessing hemodialyzers. This study was conducted to determine the prevalence of NTM and other bacteria in water samples collected over a 13-week period from 115 randomly selected dialysis centers in the United States. Total viable counts were determined by membrane filter assays; increased recovery of NTM was obtained by dosing a portion of each water sample with 1% formaldehyde (HCHO) before filtering. NTM were widely distributed and occurred with a high frequency in water supplies in dialysis centers. NTM were detected in water from 95 centers (83%), and 50% of all samples examined contained NTM. The results of this study support recommendations to use 4% HCHO or a chemical germicidal equivalent for disinfecting dialyzers that are to be reused.     

Prevalence of nontuberculous mycobacteria in water supplies of hemodialysis centers.

Infection of hemodialysis patients with nontuberculous mycobacteria (NTM) has been associated with water used in reprocessing hemodialyzers. This study was conducted to determine the prevalence of NTM and other bacteria in water samples collected over a 13-week period from 115 randomly selected dialysis centers in the United States. Total viable counts were determined by membrane filter assays; increased recovery of NTM was obtained by dosing a portion of each water sample with 1% formaldehyde (HCHO) before filtering. NTM were widely distributed and occurred with a high frequency in water supplies in dialysis centers. NTM were detected in water from 95 centers (83%), and 50% of all samples examined contained NTM. The results of this study support recommendations to use 4% HCHO or a chemical germicidal equivalent for disinfecting dialyzers that are to be reused.     

Rib lesions in chronic pulmonary tuberculosis

The diagnosis of skeletal tuberculosis in human remains has traditionally been based upon the detection of secondary skeletal lesions which result from hemotogenous dissemination of tubercle bacilli (e.g., Pott's disease). Since such lesions develop in less than 7% of cases of human tuberculosis, the paleodemography and paleoepidemiology of this disease have been difficult to assess from skeletal remains. This study presents a new diagnostic approach to tuberculosis, focusing on the skeletal manifestations of chronic pulmonary disease (which comprises approximately 90% of human-form tuberculosis). Four hundred forty-five skeletal remains from persons dying of tuberculosis during the first half of the 20th century were examined. A total of 70/445 (16%) exhibited skeletal lesions in one or more locations as a response to infection. Of these 70, 39 (56%) were found to display a specific set of lesions restricted to the internal aspect of the ribs. These lesions take one of two forms: (1) diffuse periostitis or (2) localized abscess, and appear to correspond to areas of chronic pulmonary infection. The diffuse type of rib lesion is more commonly observed than the localized type. In our observations (and according to the natural history of tuberculosis) the occurrence of chronic pulmonary tuberculosis is usually mutually exclusive with hematogenous dissemination to secondary bone locations. Thus, the detection of rib lesions in cases of chronic pulmonary disease increases the absolute sample size of skeletal tuberculosis by a factor of two in this study.     

2018—2020年平顶山地区非结核分枝杆菌菌种鉴定及耐药性分析

本文旨在观察2018—2020年河南省平顶山地区非结核分枝杆菌(nontuberculous mycobacteria,NTM)的菌种分布及耐药情况。收集2018年1月—2020年12月平顶山市传染病医院分离到的326株NTM,采用DNA微阵列芯片鉴定菌种,改良罗氏培养基比例法进行药敏试验。结果显示,从61～80岁患者中分离的NTM菌株最多,其次是41～60岁患者。共鉴定出8个NTM菌种,分别为胞内分枝杆菌(35.28%)、龟/脓肿分枝杆菌(24.85%)、鸟分枝杆菌(18.40%)、偶然分枝杆菌(5.21%)、戈登分枝杆菌(1.23%)、堪萨斯分枝杆菌(12.58%)、浅黄分枝杆菌(1.53%)、瘰疬分枝杆菌(0.92%)。NTM对异烟肼的耐药率最高,为97.85%。除戈登分枝杆菌外,其他NTM菌种对异烟肼的耐药率均＞94%;胞内分枝杆菌对丙硫异烟胺的耐药率(8.70%)相对较低,鸟分枝杆菌对丙硫异烟胺的耐药率为10.00%;龟/脓肿分枝杆菌对异烟肼、利福平、链霉素、乙胺丁醇、阿米卡星的耐药率均＞95%;偶然分枝杆菌对左氧氟沙星的耐药率为35.29%,堪萨斯分枝杆菌对左氧氟沙星的耐药率最低(7.32%);戈登分枝杆菌对异烟肼、乙胺丁醇、链霉素、对氨基水杨酸的耐药率均≥50%;浅黄分枝杆菌对乙胺丁醇、左氧氟沙星、阿米卡星、卡那霉素的耐药率均＜50%;瘰疬分枝杆菌对阿米卡星和丙硫异烟胺的耐药率为0。结果提示,2018—2020年河南省平顶山地区鉴定出的8个NTM菌种中,胞内分枝杆菌占比最高,不同菌种对不同抗结核药物的耐药性差异较大,因此菌种鉴定对临床治疗有重要意义。     

Recovery and survival of nontuberculous mycobacteria under various growth and decontamination conditions

The survival of microorganisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) complex was evaluated after various soil and water decontamination regimens. Survival was reduced by growing cells in natural waters compared with laboratory media and by inclusion of malachite green in media as an antifungal agent. Decontamination with benzalkonium chloride, while reducing survival significantly less than 1% NaOH, failed to eliminate many fungi. Recovery from soil was further reduced by transfer losses and by irreversible cell adsorption onto particulates.     

城市生活饮用水中非结核分枝杆菌调查

目的 调查上海市生活饮用水中非结核分枝杆菌的状况及主要菌种分布。方法 应用过滤法收集细菌, 并在改良罗氏培养基上培养; 通过16S rRNA 测序鉴定菌种。结果 上海市生活饮用水中非结核分枝杆菌的检出率为16. 7% , 其中自来水厂原水、出厂水和居民生活饮用终端水的检出率分别为60% 、25% 和10. 3% 。分离鉴定的非结核分枝杆菌菌种为戈登分枝杆菌及偶发分枝杆菌, 分别占90% 及10% 。结论 在上海市居民生活饮用水系统中存在非结核分枝杆菌, 因此, 应当采取有效的控制方法以保护公众的健康。     

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.     

Identification of nontuberculous mycobacteria existing in tap water by PCR-restriction fragment length polymorphism

This paper presents the finding of the possible cause of the high false-positive rate in acid-fast staining in histological examinations. Using acid-fast staining, culture, and PCR, acid-fast bacilli were detected in 83.7% of 49 hospital tap water samples and nontuberculous mycobacteria (NTM) were detected in 20.4% of the same 49 samples. The 10 NTM isolates were also identified to the species level using PCR-restriction fragment length polymorphism. Our findings indicate that NTM in hospital tap water are the possible cause of false positives in acid-fast staining and of nosocomial infection in immunocompromised patients.     

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.     

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.     

Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.     

Treatment of chronic drug-resistant pulmonary tuberculosis with rifampin and ethambutol

Twenty patients with chronic pulmonary tuberculosis completed eight months of rifampin-ethambutol treatment. Half the patients received daily 600 mg. rifampin and 25 mg./kg. ethambutol for the first two months and subsequently 15 mg./kg. The others received the same dosage of ethambutol and 450 mg. rifampin daily. The average time of sputum conversion was seven weeks and 11 weeks in the two groups respectively. The patients tolerated these drug regimens well.Rifampin blood levels and urinary excretion were studied monthly during the therapy. They indicated that after a short period of treatment the elimination of this drug became faster owing to increased excretion of rifampin, and particularly of its desacetyl metabolite, in the bile. Liver damage resulted in a slower excretion rate. Rifampin should be taken on an empty stomach because simultaneous food intake reduces the peak blood concentration.     

Genetic of modern mycobacteria of the tuberculosis complex

The review of scientific periodicals relevant to research on the mycobacteria of the tuberculosis complex with the use of modern methods of molecular biology is presented. The main mechanisms of the intraspecific variability of mycobacteria and the updated view on the tuberculosis complex mycobacteria evolution are described.     

Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers.

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.