In vitro susceptibility testing of imipenem-relebactam and tedizolid against 102 Mycobacterium abscessus isolates

Abstract

Mycobacterium abscessus is an emerging infection in people living with lung diseases including cystic fibrosis (CF) and bronchiectasis and has limited treatment options and low cure rates. The off-label use of novel antibiotics developed for other bacterial pathogens offers potential new therapeutic options. We aimed to describe the in vitro activity of imipenem, imipenem-relebactam and tedizolid against comparator antibiotics in M. abscessus isolates from Australian patients with and without CF. Susceptibility testing was performed by Clinical and Laboratory Standards Institute (CLSI) criteria against 102 clinical M. abscessus isolates including 46 from people with CF. The minimum inhibitory concentration (MICs) of imipenem-relebactam was 1-fold dilution less than of imipenem alone. The MIC50 and MIC90 of imipenem-relebactam was 8 and 16 mg/L respectively while for imipenem they were 16 and 32 mg/L. Tedizolid had an MIC50 and MIC90 of 2 and 4 mg/L, respectively. Forty non-CF isolates had linezolid susceptibility performed, with MIC50 and MIC90 values of 16 and 32 mg/L, respectively, measured. This study supports the consideration of imipenem-relebactam and tedizolid in clinical trials for M. abscessus treatment.