Genomic analysis of carbapenem-resistant non-baumannii Acinetobacter harboring chromosomal bla OXA-23 or plasmid-mediated bla NDM-1, bla IMP-14, and bla OXA-58.

INTRODUCTION: Carbapenem-resistant Acinetobacter species are among the top priority pathogens, posing a threat to public health in both hospital- and community-acquired settings. Notably, the prevalence of carbapenemase-producing non-baumannii Acinetobacter (CP-NBA) has recently increased worldwide. METHODS: This study aimed to describe the molecular characteristics of non-baumannii Acinetobacter isolates with two or more carbapenemases in South Korea. Among 590 nonduplicated carbapenem-resistant Acinetobacter species collected from community hospitals in South Korea between 2022 and 2023, a total of 13 CP-NBA isolates were used in this study. Whole-genome sequencing and in silico molecular analysis were performed to characterize their genomic features. RESULTS: Of the thirteen CP-NBA isolates, nine (four A. nosocomialis, two A. pittii, two A. seifertii, and one A. bereziniae) carried chromosomal bla OXA-23 integrated within Tn2006 in AbaRs. In addition, two A. bereziniae isolates with Rep3-T25 plasmids carrying bla VIM-2 and bla OXA-58 and one A. bereziniae isolate with the Rep3-T25 plasmid carrying bla NDM-1 and bla OXA-58 were identified. Finally, one A. pittii isolate with a putative 289 kb plasmid carrying three carbapenemase genes, bla NDM-1, bla OXA-58, and bla IMP-14, lacking a replication origin gene was detected. CONCLUSION: In conclusion, our study described the genomic structure of carbapenemase genes and related mobile genetic elements in 13 CP-NBA isolates. Although the carbapenemase genotypes are diverse, CP-NBA strains are still relatively rare in local clinics in South Korea. In particular, the bla IMP-14 gene was first identified in South Korea. These results suggest that the dissemination of CP-NBA isolates should be handled carefully in terms of transmission between bacterial strains in the clinical setting.