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J Antimicrob Chemother. 2007 Nov;60(5):1163-7. Epub 2007 Aug 29.

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

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Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea.



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


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.


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).


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

[Indexed for MEDLINE]

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