title: Dissemination of multidrug-resistant Acinetobacter baumannii carrying BlaOxA-23 from hospitals in central Taiwan.
abstract: BACKGROUND
  Imipenem-resistant Acinetobacter baumannii (IRAB) poses a great threat to healthcare systems. Production of carbapenem-hydrolyzing class D β-lactamases (CHDLs) is the major mechanism for imipenem resistance. In this study, we found a high prevalence of IRAB carrying a gene encoding CHDL, bla(OxA-23), in central Taiwan and elucidated the molecular characteristics and possible mechanisms of the spread of these isolates.
  
  
  METHODS
  During 2007, we collected 291 nonrepetitive A baumannii isolates from 10 teaching hospitals in Taiwan. The antimicrobial susceptibility of the isolates was determined by agar dilution or Etest. The genes encoding carbapenemase and related structure were detected by polymerase chain reaction mapping and sequencing, and the clonal relationship of the isolates was analyzed by pulsed-field gel electrophoresis. Plasmid localization of bla(OxA-23) was determined by extraction of plasmid with commercial kit and Southern blot analysis.
  
  
  RESULTS
  Among 142 IRAB isolates, 30 harbored the bla(OxA-23). The prevalence of IRAB with bla(OxA-23) was highest in central Taiwan compared to other areas [24.8% (27/109) vs. 1.6% (3/182); p < 0.001]. These IRAB with bla(OxA-23) were also resistant to other antimicrobial agents, except colistin. The PCR methods showed the presence of bla(OxA-51) in all isolates. We could exclude clonal spreading due to the diversity of the pulsotype. The bla(OxA-23) gene was detected in the plasmids of 6 isolates. Tn2006 was present in 22 (73.3%) isolates, and Tn2008, in 6 other isolates (26.7%). Two strains had bla(oxa-23)-ΔATPase but lacked upstream ISAba1.
  
  
  CONCLUSIONS
  The high prevalence of bla(OxA-23)-harboring IRAB in central Taiwan might be attributed to the transposition event of Tn2006.
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Mei-Hui
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan.
authors.forename: Te-Li
authors.initials: TL
authors.lastname: Chen
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan; Department of Medicine, Chutung Veterans Hospital, Chutung, Taiwan.
authors.forename: Yi-Tzu
authors.initials: YT
authors.lastname: Lee
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan. Electronic address: ludwigvantw@gmail.com.
authors.forename: Shu-Chen
authors.initials: SC
authors.lastname: Kuo
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Kwok-Woon
authors.initials: KW
authors.lastname: Yu
authors.affiliation: Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan.
authors.forename: Horng-Yunn
authors.initials: HY
authors.lastname: Dou
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan.
authors.forename: Ih-Jen
authors.initials: IJ
authors.lastname: Su
authors.affiliation: Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan.
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
mesh_terms: D000151:Acinetobacter Infections / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015139:Blotting, Southern; D016000:Cluster Analysis; D003428:Cross Infection / Q000382:microbiology*; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006784:Hospitals, Teaching; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013624:Taiwan; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D015378:Imipenem; C466679:beta-lactamase OXA-23; D001618:beta-Lactamases