Analysis of species and intra-species associations between the Mycobacterium abscessus complex strains using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST)

• MLST clearly divided the M. abscessus complex at the species level.
• Modified PFGE methods improved resolution of electrophoresis results.
• M. massiliense hsp65 type II-1 could be classified as an independent subspecies.

PFGE and MLST showed that the strains of M. massiliense hsp65 II-1 were clearly separated from the strains of M. massiliense hsp65 I or II-2 as well as the strains of M. abscessus or M. bolletii; thus, M. massiliense hsp6 5II-1 might represent an additional subspecies of M. massiliense.