The Distribution of Carbapenem-Resistant Acinetobacter Species and High Prevalence of CC92 OXA-23-Producing Acinetobacter Baumannii in Community Hospitals in South Korea

Background: Clinical isolates of Acinetobacter species in South Korea are continuously exhibiting high rates of antimicrobial resistance to carbapenems, indicating that there are public health concerns among both healthcare-associated infections and community -associated infections. The aim of this study was to describe the prevalence and characteristics of carbapenem-resistant Acinetobacter isolates originating from community hospitals. Materials and Methods: A total of 817 non-duplicated Acinetobacter species were isolated from December 2022 to July 2023 at long -term care facilities and general hospitals in 16 regions geographically distributed throughout South Korea. Bacterial identification and antimicrobial susceptibility testing were performed using the VITEK-2 system. The bacteria were identified as Acinetobacter baumannii by bla OXA-51 PCR and as non-baumannii Acinetobacter species by rpoB sequence analysis. The carbapenem resistance genes (OXA-23, OXA-48, OXA-58, IMP, VIM, NDM, GES, and KPC) were identified via PCR and sequencing. The genetic relatedness of carbapenem-resistant A. baumannii (CRAB) isolates was assessed by multilocus sequence typing. Results: A total of 659 A. baumannii and 158 non-baumannii Acinetobacter isolates, comprising 19 different species, were identified in all 16 regions. The carbapenem resistance rate was 87.4% (n=576) for the A. baumannii isolates, and all the strains produced bla OXA-23 . For non-baumannii Acinetobacter , the rate of carbapenem resistance was 8.9% (n=14); this resistance was primarily caused by bla OXA-23 (n=9), followed by bla NDM-1 (n=3) and bla VIM-2 (n=2). Of the 576 CRAB isolates, clonal complex 92 (CC92) was the predominant genotypes, followed by sequence type 229 (ST229), ST373, ST397, ST447, and ST620. Conclusion: Our results showed the distribution of Acinetobacter species and showed that CC92 CRAB clinical isolates with widespread production of bla OXA-23 were predominant in community hospitals. Our findings suggest that there is a need for urgent and effective methods to reduce carbapenem resistance in A. baumannii in South Korea.