title: Molecular epidemiology of carbapenem-non-susceptible Acinetobacter baumannii in Japan.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, 1-1, Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan. ain@med.tohoku.ac.jp
authors.forename: Shiro
authors.initials: S
authors.lastname: Endo
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yano
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hirakata
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Arai
authors.forename: Hajime
authors.initials: H
authors.lastname: Kanamori
authors.forename: Miho
authors.initials: M
authors.lastname: Ogawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimojima
authors.forename: Noriomi
authors.initials: N
authors.lastname: Ishibashi
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Aoyagi
authors.forename: Masumitsu
authors.initials: M
authors.lastname: Hatta
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yamada
authors.forename: Koichi
authors.initials: K
authors.lastname: Tokuda
authors.forename: Miho
authors.initials: M
authors.lastname: Kitagawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kunishima
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004269:DNA, Bacterial