Aono Akio, Morimoto Kozo, Chikamatsu Kinuyo, Yamada Hiroyuki, Igarashi Yuriko, Murase Yoshiro, Takaki Akiko, Mitarai Satoshi
Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-tuberculosis Association, Kiyose, Japan.
Respiratory Disease Center, Fukujuji Hospital, Japan Anti-Tuberculosis Association, Tokyo, Japan.
J Infect Chemother. 2019 Feb;25(2):117-123. doi: 10.1016/j.jiac.2018.10.010. Epub 2018 Nov 14.
The drug susceptibility of rapidly growing mycobacteria (RGM) varies among isolates. Treatment strategies similarly differ depending on the isolate, and for some, no clear strategy has been identified. This complicates clinical management of RGM. Following Clinical and Laboratory Standards Institute standard M24-A2, we assessed the susceptibility of 140 RGM isolates to 14 different antimicrobial drugs by measuring their minimal inhibitory concentrations (MICs). We also investigated the correlation of clarithromycin (CAM) MICs with the erm(41) and rrl gene mutations in the Mycobacteroides (Mycobacterium) abscessus complex, the rrl mutation in Mycobacteroides (Mycobacterium) chelonae, and the erm(39) mutation in Mycolicibacterium (Mycobacterium) fortuitum to determine the contribution of these mutations to CAM susceptibility. The five species and subspecies examined included 48 M. abscessus subsp. abscessus isolates (34.3%), 35 (25.0%) being M. abscessus subsp. massiliense, and two (1.4%) being M. abscessus subsp. bolletii. The M. abscessus complex accounted for 85 isolates (60.7%) in total, whereas 43 isolates (30.7%) were M. fortuitum, and 12 (8.6%) were M. chelonae. Our results demonstrated species-specific susceptibility to antimicrobials. In most cases, susceptibility to CAM could be predicted based on genetic pattern, but since one isolate did not fit that pattern, MIC values needed to be measured. Some isolates also exhibited rates of resistance to other drugs that differed from those previously reported in other locations, indicating that accurate identification of the bacterial isolate and use of the correct method for determining MIC are both important for the diagnosis of RGM.
快速生长分枝杆菌（RGM）的药敏性在不同分离株之间存在差异。治疗策略同样因分离株而异，对于某些分离株，尚未确定明确的策略。这使得RGM的临床管理变得复杂。按照临床和实验室标准协会标准M24 - A2，我们通过测量140株RGM分离株对14种不同抗菌药物的最低抑菌浓度（MIC）来评估其药敏性。我们还研究了克拉霉素（CAM）的MIC与脓肿分枝杆菌复合群中erm(41)和rrl基因突变、龟分枝杆菌中rrl基因突变以及偶然分枝杆菌中erm(39)基因突变之间的相关性，以确定这些突变对CAM药敏性的影响。所检测的五个菌种和亚种包括48株脓肿分枝杆菌脓肿亚种分离株（34.3%）、35株（25.0%）马赛分枝杆菌、2株（1.4%）博勒分枝杆菌。脓肿分枝杆菌复合群总共占85株（60.7%），而43株（30.7%）为偶然分枝杆菌，12株（8.6%）为龟分枝杆菌。我们的结果表明了不同菌种对抗菌药物的药敏性具有特异性。在大多数情况下，基于基因模式可以预测对CAM的药敏性，但由于有一个分离株不符合该模式，所以需要测量MIC值。一些分离株对其他药物的耐药率也与之前在其他地区报道的不同，这表明准确鉴定细菌分离株并使用正确的方法测定MIC对于RGM的诊断都很重要。
