Objective To investigate antimicrobial resistance profiles of carbapenem-resistant Enterobacter spp. (CREn) and the bactericidal effects of aztreonam combined with avibactam. Methods The CREn strains isolated from the West China Hospital of Sichuan University between 2016 and 2021 were identified by gyrB gene amplification and subsequent sequencing. The drug sensitivity results, sample types and distribution of relevant patient departments of these strains were summarized. Colistin-resistant and -intermediate strains were selected to carry out the bactericidal test of colistin and aztreonam combined with avibactam. Results A total of 110 clinical strains of CREn were included. The most common strain was Enterobacter xiangfangensis (91 strains), the highest proportion was in the intensive care unit (27.27%), and the proportion of respiratory tract samples was more than 40%. The antimicrobial sensitivity results showed that CREns were all resistant to carbapenems, the resistance rate to colistin was 23.64%, and the resistance rate to aztreonam combined with avibactam was 0. Among other antimicrobial agents, the antimicrobial resistance rate of amikacin and tigecycline were less than 10%. The time-kill curve showed that for colistin-intermediate strains, colistin could achieve bactericidal effect in a shorter time than aztreonam combined with avibactam. However, whether the strain was resistant to colistin or not, the bactericidal rate of 2 μg/mL aztreonam combined with avibactam in 24 hours could exceed 99%. Conclusion CREn is resistant to most commonly used clinical antibacterial drugs, but remains sensitive to aztreonam combined with avibactam, and aztreonam combined with avibactam has bactericidal effect on it.
