Chromosomal co-carriage of blaOXA-23 and blaOXA-500 in a carbapenem-resistant Acinetobacter pittii isolate
Carbapenem resistance in non-baumannii Acinetobacter has been increasingly reported worldwide. This study investigated the genetic basis of carbapenem resistance in Acinetobacter pittii isolate KBN12P06770 carrying bla<sub>OXA-23</sub> and bla<sub>OXA-500</sub> using whole-genome sequencing. Two carbapenemase genes were located on the chromosome. Two copies of bla<sub>OXA-23</sub> located on Tn2006 were identified. Additional chromosomally encoded antimicrobial resistance genes, including bla<sub>ADC-18</sub> and ant(3")-IIc, as well as efflux pump genes (adeIJK, adeFGH, abeM, and abaQ), were identified, with the exception of plasmid-borne ant(2")-Ia. qPCR analysis revealed that the bla<sub>OXA-23</sub> was more highly expressed than bla<sub>OXA-500</sub>. Notably, bla<sub>OXA-23</sub> featured the Ser225Pro substitution, first characterized in this study, which may enhance β-lactamase activity based on structural modeling. Furthermore, multilocus sequence typing (MLST) assigned KBN12P06770 to ST1611 within clonal complex 63 (CC63), with close clustering to ST2737 indicating recent divergence. The comprehensive genomic analysis of A. pittii isolate KBN12P06770 highlights the complex genetic architecture underlying carbapenem resistance.
Authors
- Shukho Kim (ORCID: https://orcid.org/0000-0003-3322-7984)
- Je Chul Lee (ORCID: https://orcid.org/0000-0001-6203-604X)
- Md Shohel Rana
Institutions
- Kyungpook National University Hospital (KR)
- Kyungpook National University (KR)
Publication Details
- Journal
- Infection Genetics and Evolution
- Published
- 2025-10-29
- DOI
- https://doi.org/10.1016/j.meegid.2025.105845
- Citations
- 1
- Primary Topic
- Antibiotic Resistance in Bacteria
- Type
- article
- Field-Weighted Citation Impact
- 0.59