Comparing the Utilities of Different Multilocus Sequence Typing Schemes for Identifying Outbreak Strains of Mycobacterium abscessus subsp. massiliense

Outbreaks of infections by Mycobacterium abscessus, particularly subspecies massiliense, are increasingly reported worldwide. Several multilocus sequence typing (MLST) protocols for grouping international outbreak strains have been developed but not yet directly compared. Using the three-gene (hsp65, rpoB, and secA1), seven-gene (argH, cya, glpK, gnd, murC, pta, and purl) and thirteen-gene (all of the preceding genes plus gdhA, pgm, and pknA) MLST schemes, we identified 22, 38, and 40 unique sequence types (STs), respectively, among a total of 139 nonduplicated M. abscessus isolates. Among subspecies massiliense, three-gene MLST not only clustered all outbreak strains together (in 100% agreement with the seven-gene and thirteen-gene schemes), but it also distinguished between two new STs that would have been grouped together by the seven-gene MLST but were distinct by the thirteen-gene MLST owing to differences in hsp65, rpo8, and pknA. Here, we show that an abbreviated MLST may be useful for simultaneous identification of M. abscessus the subspecies level and screening M. abscessus subsp. massiliense isolates with outbreak potential.