High rates of resistance to colistin and polymyxin B in subgroups of Acinetobacter baumannii isolates from Korea.
OBJECTIVE
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.
Ko
Kwan Soo
KS
Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea.
Suh
Ji Yoeun
JY
Kwon
Ki Tae
KT
Jung
Sook-In
SI
Park
Kyong-Hwa
KH
Kang
Cheol In
CI
Chung
Doo Ryeon
DR
Peck
Kyong Ran
KR
Song
Jae-Hoon
JH
D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D003091:Colistin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D007723:Korea / Q000453:epidemiology; D010802:Phylogeny; D011112:Polymyxin B / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D011112:Polymyxin B; D003091:Colistin