Independent emergence of colistin-resistant Acinetobacter spp. isolates from Korea.
High colistin resistance rates in Acinetobacter spp. were recently reported in Korean hospitals (J. Antimicrob. Chemother 2007;60:1163). In this study, we investigated if colistin-resistant Acinetobacter spp. isolates from Korean hospitals disseminated clonally or emerged independently. Multilocus sequence typing (MLST) analysis was performed for 58 colistin-resistant Acinetobacter spp. isolates: 8 isolates of the Acinetobacter baumannii subgroup A, 16 isolates of the A. baumannii subgroup B, and 34 isolates of the genomic species 13TU. A phylogenetic tree inferred from concatenated sequences of 7 MLST loci showed a clear distinction among the 3 Acinetobacter groups. In the MLST analysis, most colistin-resistant Acinetobacter spp. isolates showed different allele profiles at the 7 loci; that is, they belonged to different clones. Despite the clear distinction between the 3 Acinetobacter groups, interrelationships among the 3 groups were not consistent within the gene trees. In addition, some isolates showed clustering incongruent with their species or group identities in some gene trees. MLST analysis indicated that most colistin-resistant Acinetobacter spp. isolates from Korean hospitals arose independently. Considering the increasing use of colistin and the high recombination rate of Acinetobacter spp., independent but frequent emergence of colistin resistance in Acinetobacter spp. isolates is of great concern.
Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, South Korea.
Young Kyoung
YK
Park
Sook-In
SI
Jung
Kyong-Hwa
KH
Park
Hae Suk
HS
Cheong
Kyong Ran
KR
Peck
Jae-Hoon
JH
Song
Kwan Soo
KS
Ko
D000150:Acinetobacter / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*; D000151:Acinetobacter Infections / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques / Q000379:methods; D016000:Cluster Analysis; D003091:Colistin / Q000494:pharmacology*; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005838:Genotype; D006801:Humans; D007723:Korea; D017720:Molecular Epidemiology; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D003091:Colistin