Department of Microbiology, Karaj Branch, Islamic Azad University, Karaj, Iran.
Mycobacteriology Research Center (MRC), National Research Institute of Tuberculosis and Lung Disease (NRITLD), World Health Organization Collaborating Centre, Shahid Beheshti University of Medical Sciences (Medical Campus), Darabad, PO 19575/154, Tehran, 19556, Iran.
Curr Microbiol. 2021 Jun;78(6):2324-2331. doi: 10.1007/s00284-021-02486-w. Epub 2021 Apr 13.
Mycobacterium simiae is an emerging nontuberculous mycobacterium (NTM) and an opportunistic pathogen which is described mainly in Asia and presents in the environment that can cause pulmonary infection. The objective of this study is to characterize M. simiae clinical isolates using mycobacterial interspersed repetitive unit variable-number tandem repeats (MIRU-VNTR) typing for the differentiation of the strains. A total of 169 clinical isolates of NTM were recovered from patients suspected of having tuberculosis (TB)-like and related infections. After isolation and identification of mycobacterial strains by conventional biochemical and PCR-based tests, M. simiae strains were confirmed using restriction fragment length polymorphism (RFLP)-based identification assay. Furthermore, drug susceptibility and MIRU-VNTR typing was performed using on the clinical isolates of M. simiae. Out of 169 NTM strains, 92 (54.4%) isolates were identified as M. simiae. Antibiotic susceptibility experiments indicated that all 92 M. simiae isolates were resistant to first line antimycobacterial agents. Moreover, 8 (8.6%) M. simiae isolates were resistant to ciprofloxacin; and 6 (6.5%) were resistant to both amikacin and kanamycin, while the remaining were susceptible to second line antimycobacterial agents. MIRU-VNTR analysis showed that the M. simiae isolates were classified in four distinct M. simiae clusters and two single types. The minimum spanning analysis revealed that the isolates were grouped in three complexes. The data suggested that MIRI-VNTR typing is useful for typing of M. simiae isolates, however, MIRU-16 locus was absolutely absent in M. simiae.
猿分枝杆菌是一种新兴的非结核分枝杆菌（NTM）和机会性病原体，主要在亚洲被描述，并存在于环境中，可引起肺部感染。本研究的目的是使用分枝杆菌插入重复单元可变数串联重复（MIRU-VNTR）分型来对 M. simiae 临床分离株进行特征分析，以区分菌株。从疑似患有结核样和相关感染的患者中回收了总共 169 株 NTM 临床分离株。通过常规生化和基于 PCR 的试验对分枝杆菌菌株进行分离和鉴定后，使用基于限制片段长度多态性（RFLP）的鉴定试验确认了 M. simiae 菌株。此外，对 M. simiae 的临床分离株进行了药敏试验和 MIRU-VNTR 分型。在 169 株 NTM 菌株中，有 92 株（54.4%）鉴定为 M. simiae。抗生素药敏实验表明，所有 92 株 M. simiae 分离株均对一线抗分枝杆菌药物耐药。此外，有 8 株（8.6%）M. simiae 分离株对环丙沙星耐药；有 6 株（6.5%）对阿米卡星和卡那霉素均耐药，其余对二线抗分枝杆菌药物敏感。MIRU-VNTR 分析表明，M. simiae 分离株分为四个不同的 M. simiae 聚类和两个单型。最小生成树分析显示，这些分离株分为三个复合体。数据表明 MIRI-VNTR 分型对 M. simiae 分离株的分型很有用，但是 MIRU-16 基因座在 M. simiae 中绝对不存在。
