Antibiotic susceptibility of reference and clinical strains of slowly growing nontuberculous mycobacteria of 5 species rarely isolated in China

ObjectiveTo explore the susceptibility of clinical isolates and reference strains of 5 species of nontuberculous mycobacteria, including Mycolicibacter kumamotonensis, Mycobacterium lentiflavum, Mycobacterium shimoidei, Mycobacterium szulgai, Mycobacterium triplex, which are rarely isolated in China.

MethodsThe minimum inhibitory concentrations (MICs) of 36 antibiotics to 10 clinical isolates (1 strain of M. kumamotonensis, 3 strains of M. lentiflavum, 2 strains of M. shimoidei, 2 strains of M. szulgai and 2 strains of M. triplex) and 5 reference strains of each species were detected with microplate Alamar Blue assay. The drug susceptibility patterns of the strains were then analyzed, and the drug susceptibility patterns were compared between clinical isolates and reference strains.

ResultsThe majority of the five species strains were sensitive to rifabutin, rifapentine, aminoglycosides, most of fluoroquinolones, capreomycin, clarithromycin, roxithromycin, azithromycin, linezolid and clofazimine. In addition, M. triplex strains were found to be sensitive to cephalosporins.

ConclusionM. kumamotonensis, M. lentiflavum, M. shimoidei, M. szulgai and M. triplex were sensitive to multi antibiotics, while some clinical strains showed resistances. It is suggested that drug susceptibility test and combined drug therapy are necessary to treat the infections caused by these five species.