J Glob Antimicrob Resist. 2022 Jun 2:S2213-7165(22)00132-1. doi: 10.1016/j.jgar.2022.05.027. Online ahead of print.
ABSTRACT
BACKGROUND: The Mycobacterium avium complex (MAC), comprising a series of subspecies, has a worldwide distribution, with differences in drug susceptibility among subspecies. This study aimed to assess the composition of MAC and susceptibility differences among subspecies in mainland China.
METHODS: A total of 287 MAC clinical strains were included in the study. Multitarget sequences were applied to accurately identify subspecies, and a microdilution method was used to evaluate minimum inhibitory concentrations (MICs) among subspecies using Sensititre SLOMYCO plates.
RESULTS: M. intracellular (N=169), M. avium (N=52), M. chimaera (N=22), M. marseillense (N=25), M. colombiense (N=14), M. yongonense (N=4), M. vulneris (N=3) and M. timonense (N=2) were isolated from MAC. Clarithromycin, amikacin and rifabutin showed lower MIC50 and MIC90 values than other drugs, and the resistance rates of clarithromycin, amikacin, linezolid and moxifloxacin were 6.3%, 10.5%, 51.9% and 46.3%, respectively. The resistance rates of clarithromycin and moxifloxacin in the initial treatment group were significantly lower than those in the retreatment group (4.09% vs. 12.94%; 30.41% vs. 75.29%; p<0.05). Drug susceptibility differences were observed in clarithromycin and moxifloxacin among the 5 major subspecies (p<0.05); however, those statistically significant differences disappeared when MACs were divided into two groups according to previous anti-TB treatment history.
CONCLUSIONS: This study revealed that MAC, primarily comprising M. intracellulare, was susceptible to clarithromycin, amikacin and rifabutin. Drug susceptibility among subspecies did not exhibit intrinsic differences in our study. Previous anti-TB treatment patients are more resistant to drugs; thus, attention should be given to those patients in the clinic.
PMID:35660663 | DOI:10.1016/j.jgar.2022.05.027