Molecular epidemiology of carbapenem-non-susceptible acinetobacter baumannii in Japan

Shiro Endo, Hisakazu Yano, Yoichi Hirakata, Kazuaki Arai, Hajime Kanamori, Miho Ogawa, Masahiro Shimojima, Noriomi Ishibashi, Tetsuji Aoyagi, Masumitsu Hatta, Mitsuhiro Yamada, Koichi Tokuda, Miho Kitagawa, Hiroyuki Kunishima, Mitsuo Kaku

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Objectives: Acinetobacter baumannii presents a clinical challenge when it is non-susceptible to carbapenems. The prevalence of carbapenem-non-susceptible A. baumannii in Japan is unclear, as previous studies have been limited in scope. We investigated the spread of carbapenem-non-susceptible A. baumannii in Japan and performed a comparison with findings from overseas. Methods: A total of 305 non-duplicate clinical isolates of Acinetobacter spp. from 176 medical facilities in all geographical regions of Japan were tested for susceptibility to antimicrobial agents by the agar dilution method. Isolates with MICs of imipenem ≥4 mg/L underwent PCR analysis of OXA-type β-lactamase gene clusters and metallo-β-lactamase genes. These isolates were further analysed by sequencing of OXA-type β-lactamases and by multilocus sequence typing (MLST). Results: Fifty-five of the 305 clinical isolates had MICs of imipenem ≥4 mg/L. The OXA-51-like carbapenemase gene was detected in 52 of these 55 isolates. Within the OXA-51-like gene cluster, OXA-66 was found in 43 (82.7%) of the 52 isolates. MLST identified the following sequence types (STs): ST74, ST76, ST92, ST106, ST188 and ST195 in 2 (3.8%), 2 (3.8%), 40 (76.9%), 5 (9.6%), 2 (3.8%) and 1 (1.9%) of the isolates, respectively. In particular, ST92 was found in 31 (91.2%) of the 34 A. baumannii isolates with MICs of imipenem ≥16 mg/L. Conclusions: This is the first report on the molecular epidemiology of A. baumannii with MICs of imipenem ≥4 mg/L in Japan. OXA-66 and ST92 were dominant among these isolates.

Original languageEnglish
Article numberdks094
Pages (from-to)1623-1626
Number of pages4
JournalJournal of Antimicrobial Chemotherapy
Issue number7
Publication statusPublished - 2012 Jul


  • CC92
  • MLST
  • OXA-66
  • ST92

ASJC Scopus subject areas

  • Pharmacology
  • Microbiology (medical)
  • Pharmacology (medical)
  • Infectious Diseases


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