Role of OXA-23 and AdeABC efflux pump for acquiring carbapenem resistance in an Acinetobacter baumannii strain carrying the blaOXA-66 gene

Yangsoon Lee, Jong Hwa Yum, Chang Ki Kim, Dongeun Yong, Eun Hee Jeon, Seok Hoon Jeong, Jee Young Ahn, Kyungwon Lee

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21 Citations (Scopus)


This study was performed to determine the mechanisms for acquiring carbapenem resistance in six clinical isolates of Acinetobacter baumannii. All isolates showed similar SmaI-macrorestriction patterns with less than 3 band differences by PFGE. The isolates showed a high level resistance (>32 mg/L) to both imipenem and meropenem by Etest. Phe-Arg-β-naphthylamide lowered the MICs of carbapenems. Realtime PCR experiments showed that expression levels of the adeB gene in the six A. baumannii isolates were 10- to 40-times higher than those of imipenem-susceptible strains. Direct sequencing of PCR products showed that all isolates carried the blaOXA-23 gene, which was preceded by ISAba1. The blaOXA-23 probe hybridized with approximately 500-kb I-CeuI chromosomal fragments, but not with a plasmid. These findings suggest that overexpression of the AdeABC efflux pump as well as chromosome-borne OXA-23 may play a role in acquiring carbapenem resistance in our A. baumannii isolates.

Original languageEnglish
Pages (from-to)43-48
Number of pages6
JournalAnnals of Clinical and Laboratory Science
Issue number1
Publication statusPublished - 2010 Dec 1


All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology and Allergy
  • Pathology and Forensic Medicine
  • Immunology
  • Molecular Biology
  • Hematology
  • Clinical Biochemistry
  • Medical Laboratory Technology

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