Introduction: Non-tuberculous mycobacteria, although identified as pathogenic to humans long time ago, are emerging as the new threat in the past two decades. Even in tuberculosis endemic country such as India, they are being isolated from the clinical specimens more often than previously. This change in trend is of concern, because they are often misdiagnosed as Mycobacterium tuberculosis or even as drug-resistant tuberculosis. Objectives: A prospective, observational study was planned to identify the frequency and risk factors associated with pulmonary and extrapulmonary non-tuberculous mycobacterial (NTM) infections. Agreement between two commercially available molecular systems, namely GenoType Mycobacteria CM assay and matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS) used in the identification of mycobacterial species is also analysed. Materials and Methods: NTM isolated from pulmonary and extrapulmonary clinical specimens over a period of 1½ year was included in the study. Patient demographics were collected, and the risk factors associated with NTM infections were analyzed. NTM grown on culture was speciated using GenoType Mycobacteria CM assay (HAIN Life Sciences, Germany) and MALDI TOF MS (bioMerieux, France). Drug-susceptibility tests were done for rapid-growing NTM using E-test (bioMerieux, France). Results: Eight hundred and fifty-four mycobacteria were isolated from 5009 specimens processed during the study period. Out of the mycobacteria grown, 74 (8.7%) were NTM and 780 (91.3%) were Mycobacterium tuberculosis complex. The NTM isolated from pulmonary specimens were 46 (62.16%) and from extrapulmonary sources were 28 (37.84%). The most common species isolated from pulmonary specimens was Mycobacterium intracellulare and from extrapulmonary specimens was Mycobacterium abscessus. Concordance between the two commercial assays used for the identification was 96.49%. The most common risk factor associated with pulmonary NTM was previous lung pathology, while with extrapulmonary NTM infection was previous surgical intervention. Drug-susceptibility tests for rapid growers showed amikacin and clarithromycin as the most active drugs in vitro. Conclusions: NTM plays a significant role in causing pulmonary and extrapulmonary infections even in our part of the country with high endemicity of tuberculosis. NTM has emerged as important pathogens even in the immunocompetent patients. There is a need for rapid diagnosis and susceptibility testing of NTM to aid physicians administer timely and appropriate treatment to the patients.


中文翻译：

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结核病高发区 NTM 肺部和肺外感染的流行病学和危险因素。



简介：非结核分枝杆菌虽然很早就被认为对人类具有致病性，但在过去二十年中正在成为新的威胁。即使在印度等结核病流行国家，也比以前更频繁地从临床标本中分离出它们。这种趋势的变化令人担忧，因为它们经常被误诊为结核分枝杆菌，甚至被误诊为耐药结核病。目的：计划进行一项前瞻性观察性研究，以确定与肺部和肺外非结核分枝杆菌 (NTM) 感染相关的频率和危险因素。还分析了两种市售分子系统（即 GenoType 分枝杆菌 CM 测定法和用于鉴定分枝杆菌物种的基质辅助激光解吸/电离飞行时间质谱法 (MALDI TOF MS)）之间的一致性。材料和方法：本研究纳入了历时 1.5 年从肺部和肺外临床标本中分离出的 NTM。收集患者人口统计数据，并分析与 NTM 感染相关的危险因素。使用 GenoType 分枝杆菌 CM 测定（HAIN Life Sciences，德国）和 MALDI TOF MS（bioMerieux，法国）对培养物上生长的 NTM 进行物种鉴定。使用 E-test（法国生物梅里埃）对快速生长的 NTM 进行药物敏感性测试。结果：从研究期间处理的 5009 份标本中分离出 854 种分枝杆菌。在生长的分枝杆菌中，74 株（8.7%）为 NTM，780 株（91.3%）为结核分枝杆菌复合群。肺部标本中分离出的 NTM 为 46 种（62.16%），肺外来源的 NTM 为 28 种（37.84%）。 从肺部标本中分离出的最常见菌种是细胞内分枝杆菌，从肺外标本中分离出的最常见菌种是脓肿分枝杆菌。用于鉴定的两种商业化验之间的一致性为 96.49%。与肺部 NTM 相关的最常见危险因素是既往肺部病理，而肺外 NTM 感染则是既往手术干预。对快速生长者的药物敏感性测试显示阿米卡星和克拉霉素是体外最活跃的药物。结论：即使在我国结核病高发地区，NTM 在引起肺部和肺外感染中也起着重要作用。即使在免疫功能正常的患者中，NTM 也已成为重要的病原体。需要对 NTM 进行快速诊断和药敏测试，以帮助医生对患者进行及时、适当的治疗。