Determination of the antimicrobial susceptibility and molecular profile of clarithromycin resistance in the Mycobacterium abscessus complex in Japan by variable number tandem repeat analysis

Mycobacterium abscessus complex, including three subspecies-M. abscessus, M. massiliense, and M. bolletii-is resistant to a variety of antibiotics so limited treatment options are available. The susceptibility of these subspecies to antimicrobial agents depends in particular on the erm(41) sequevar and rrl mutations in the 23S rRNA, which are potentially related to clarithromycin (CLR) resistance. The purpose of this study was to carry out identification and molecular characterization of these subspecies based on variable number of tandem repeats (VNTR) analysis. Twenty-four M. abscessus complex strains were identified as M. abscessus and M. massiliense and these subspecies could be discriminated between based on their resistance to CLR, as determined by truncation or mutation of erm(41) or mutation of rrl, as illustrated by their VNTR patterns. In conclusion, we confirmed that the CLR susceptibility profiles could be differentiated according to the subspecies of M. abscessus complex strains by their VNTR patterns.