Prevalence, Antimicrobial Susceptibility, and Carbapenem Resistance of Non-baumannii Acinetobacter Species in Three Korean Hospitals

Non-baumannii Acinetobacter species are increasingly prevalent as opportunistic pathogens in the hospitals worldwide. However, the current information of epidemiology and antimicrobial susceptibility of non-baumannii Acinetobacter species is limited in Korea. This study investigated the species distribution, anti-microbial susceptibility, and carbapenem resistance mechanisms of 65 non-baumannii Acinetobacter isolates from three Korean hospitals during 2017 to 2020. Sixteen different Acinetobacter species were identified. Among them, A. ursingii (n = 16), A. junii (n = 11), and A. nosocomialis (n = 9) were prevalent, accounting for 55.4% of the isolates. A half (50.8%) of non-baumannii Acinetobacter isolates were susceptible to all antimicrobial agents tested. Non-baumannii Acinetobacter isolates exhibited the highest resistance rate to piperacillin (26.2%), whereas no isolates were resistant to minocycline and tigecycline. Seven isolates were resistant to carbapenems by the production of carbapenemases. Ambler class B (bla_NDM-1 and bla_VIM-2) and class D carbapenemase genes (bla_OXA-23, bla_OXA-58, bla_OXA-211, and bla_OXA-213) were detected. Three isolates carried two or more carba-penemase genes. One A. calcoaceticus isolate co-carried bla_VOXA-58, bla_OXA-213, and bla_NDM-1. In conclusion, this study provides new insights into antimicrobial susceptibility and carbapenem resistance mechanisms of Korean non-baumannii Acinetobacter species. The spread of carbapenem resistance genes should be carefully monitored among non-baumannii Acinetobacter species.