Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
Faculdade de Medicina, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
J Bras Pneumol. 2020;46(2):e20190184. doi: 10.36416/1806-3756/e20190184. Epub 2020 May 11.
Nontuberculous mycobacteria (NTM) are a heterogeneous group of bacteria that are widely distributed in nature and associated with opportunistic infections in humans. The aims of this study were to identify NTM in patients with suspected tuberculosis who presented positive cultures and to evaluate the genetic diversity of strains identified as Mycobacterium avium.
We studied pulmonary and extrapulmonary samples obtained from 1,248 patients. The samples that tested positive on culture and negative for the M. tuberculosis complex by molecular identification techniques were evaluated by detection of the hsp65 and rpoB genes and sequencing of conserved fragments of these genes. All strains identified as M. avium were genotyped using the eight-locus mycobacterial interspersed repetitive unit-variable-number tandem-repeat method.
We found that NTM accounted for 25 (7.5%) of the 332 mycobacteria isolated. Of those 25, 18 (72%) were M. avium, 5 (20%) were M. abscessus, 1 (4%) was M. gastri, and 1 (4%) was M. kansasii. The 18 M. avium strains showed high diversity, only two strains being genetically related.
These results highlight the need to consider the investigation of NTM in patients with suspected active tuberculosis who present with positive cultures, as well as to evaluate the genetic diversity of M. avium strains.
非结核分枝杆菌（NTM）是一组广泛分布于自然界的异质性细菌，与人类机会性感染有关。本研究旨在鉴定培养阳性的疑似肺结核患者中的 NTM，并评估鉴定为鸟分枝杆菌的菌株的遗传多样性。
我们研究了来自 1248 例患者的肺和肺外样本。通过分子鉴定技术检测到培养阳性但结核分枝杆菌复合体阴性的样本，用 hsp65 和 rpoB 基因检测和这些基因的保守片段测序进行评估。所有鉴定为鸟分枝杆菌的菌株均采用 8 个基因座分枝杆菌插入重复单元-可变数串联重复基因分型方法进行基因分型。
我们发现，332 株分离的分枝杆菌中，有 25 株（7.5%）为 NTM。在这 25 株中，18 株（72%）为鸟分枝杆菌，5 株（20%）为脓肿分枝杆菌，1 株（4%）为胃分枝杆菌，1 株（4%）为堪萨斯分枝杆菌。18 株鸟分枝杆菌菌株表现出高度多样性，只有两株具有遗传相关性。
这些结果强调了需要考虑对培养阳性的疑似活动性肺结核患者进行 NTM 调查，以及评估鸟分枝杆菌菌株的遗传多样性。
