In Vitro Susceptibility Testing of Bedaquiline against Mycobacterium abscessus Complex.

We performed bedaquiline broth microdilution susceptibility testing using Clinical and Laboratory Standards Institute (CLSI) guidelines on 104 nonduplicate isolates of Mycobacterium abscessus complex [ M. abscessus subsp. abscessus (76); M. abscessus subsp. massiliense (10); M. abscessus subsp. bolletii (2); and M. abscessus subsp. abscessus - M. abscessus subsp. massiliense hybrid, i.e., M. abscessus subsp. abscessus by rpoB gene and M. abscessus subsp. massiliense by erm (41) gene (16)]. All isolates from patients not known to have been on bedaquiline prior had MIC values of ≤0.25 μg/ml. The bedaquiline MIC50 value for all 76 isolates of M. abscessus subsp. abscessus and 16 isolates of M. abscessus subsp. abscessus - M. abscessus subsp. massiliense hybrid was 0.06 μg/ml. The MIC50 and MIC90 values for 10 isolates of M. abscessus subsp. massiliense were 0.12 μg/ml. Only two isolates of M. abscessus subsp. bolletii were tested with bedaquiline MICs of 0.06 μg/ml. Our study suggests that oral bedaquiline may have potential use in the treatment of disease caused by the M. abscessus complex. Combination therapy with other agents (imipenem, cefoxitin, amikacin, and/or tigecycline) is recommended.