LAUSR

OBJECTIVES To compare the antibiotic susceptibility profiles of Mycobacterium abscessus complex (MABC) and investigate the relationship between susceptibility profiles and genetic mechanism of macrolides resistance. METHODS Over 200 isolates collected from respiratory specimens between 2014 and 2018 were randomly analyzed in this study. The minimum inhibitory concentrations of 10 potential antimicrobial agents were determined using the microplate alamar blue assay. RESULTS We identified 43 MABC isolates, including 32 M. abscessus subsp. abscessus [(M. abscessus), (6 strains isolated from immunocompromised patients)] and 11 M. abscessus subsp. massiliense (M. massiliense). The majority of MABC isolates were susceptible to amikacin (96.9% and 100.0%, respectively), linezolid (96.9% and 100.0%, respectively), cefoxitin (100.0% and 100.0%, respectively), imipenem (90.6% and 72.6%, respectively) and tobramycin (90.6% and 72.6%, respectively). The resistant indexes to clarithromycin and doxycycline in isolates of M. abscessus (68.8%, 100.0%) were significantly higher than that of M. massiliense (18.2%, 63.6%; p < 0.05), whereas the percentage of tobramycin resistant isolates among M. abscessus (9.4%) was significantly lower than M. massiliense (27.3%, p = 0.007). Sequencing analyses showed significant differences between erm(41) of M. abscessus and M. massiliense. CONCLUSION Mycobacterium abscessus is the dominant pathogen of pulmonary MABC infections in our hospital. Aminoglycosides (amikacin and tobramycin), β-lactams (cefoxitin and imipenem) and linezolid exhibited potent inhibition activity against MABC in vitro. The erm(41) gene can be a promising marker to predict macrolide susceptibility for M. abscessus.