Purpose: In recent years, less options are available for treating carbapenem-resistant Acinetobacter baumannii  and carbapenem-resistant Pseudomonas aeruginosa . The present study investigates the susceptibility rates to imipenem/relebactam for the treatment of intra-abdominal infections (IAIs), respiratory tract infections (RTIs) and urinary tract infections (UTIs) caused by A. baumannii  and P. aeruginosa  in China.
Patients and Methods: A total of 1886 P. aeruginosa  and 1889 A. baumannii  isolates were collected in 21 centers (7 regions) as a part of the global SMART surveillance program between 2015 and 2018. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) recommendations using the broth microdilution methodology at Peking Union Medical College Hospital.
Results: For P. aeruginosa , overall susceptibility rates to imipenem/relebactam were 84.2% at a CLSI breakpoint of ≤ 2 mg/L compared to 55.7% for imipenem. Susceptibility rates of imipenem-non-susceptible P. aeruginosa  to imipenem/relebactam were 64.4% and for multidrug-resistance (MDR) P. aeruginosa  susceptibility rates were increased from 25.2% for imipenem to 65.8% for imipenem/relebactam. The susceptibilities of imipenem-non-susceptible and MDR P. aeruginosa  strains were similarly restored by imipenem/relebactam in non-ICU and ICU wards. The rate of imipenem-non-susceptibilities A. baumannii  isolates was 79.0%, whereas the MDR rate was 81.9%. Relebactam did not change the susceptibilities of imipenem-non susceptible or MDR A. baumannii  isolates.
Conclusion: Imipenem/relebactam provides a therapy option to treat infections caused by MDR or imipenem-non-susceptible P. aeruginosa  but not A. baumannii  infections in China.
Keywords: carbapenem-resistance, extended-spectrum β-lactamase, multidrug-resistance, β-lactamase inhibitor, carbapenemase