High rates of resistance to colistin and polymyxin B in subgroups of Acinetobacter baumannii isolates from Korea

J Antimicrob Chemother. 2007 Nov;60(5):1163-7. doi: 10.1093/jac/dkm305. Epub 2007 Aug 29.

Abstract

Objectives: To investigate antimicrobial resistance in clinical isolates of Acinetobacter spp. from two Korean hospitals.

Methods: Two hundred and sixty-five isolates of Acinetobacter spp. from two Korean hospitals were collected and were identified to species level using partial rpoB gene sequences. Antimicrobial susceptibility testing was performed using a broth microdilution method.

Results: rpoB gene sequences indicated that 214 isolates (80.8%) were Acinetobacter baumannii, and allowed these to be classified into three subgroups (I, II and III); 142 isolates (53.6%) belonged to subgroup I, 54 (20.4%) to subgroup II and 18 (6.8%) to subgroup III. Forty-eight isolates (18.1%) and 74 isolates (27.9%) were resistant to polymyxin B and colistin, respectively. However, antimicrobial resistance rates varied markedly between subgroups. While A. baumannii subgroup I showed low resistance rates to polymyxin B and colistin (2.1% and 7.0%, respectively), subgroups II and III showed high resistance rates to these antibiotics (38.9% and 64.8% in subgroup II and 72.2% and 88.9%, in subgroup III, respectively). Multidrug resistance was also significantly more frequent in subgroup I (45.1%) than in subgroups II and III (13.0% and 16.7%, respectively).

Conclusions: Our data indicate that subgroup identification of A. baumannii may aid selection of appropriate antimicrobial agents for the treatment of Acinetobacter infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections / epidemiology
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / genetics
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics
  • Colistin / pharmacology*
  • Drug Resistance, Multiple, Bacterial
  • Korea / epidemiology
  • Phylogeny
  • Polymyxin B / pharmacology*

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Polymyxin B
  • Colistin