C2-3869. Independent Emergence of Colistin-Resistant Acinetobacter Iolates from Korea
Session: Poster Session: Acinetobacter: Global Impact
Tuesday, October 28, 2008: 12:00 AM
Room: Hall C
Background: High colistin resistance rate in Acinetobacter spp. was recently reported in Korean hospitals (Ko et al. JAC 60:1163-1167, 2007). In this study, we investigated if colistin-resistant Acinetobacter spp. isolates from Korean hospitals disseminated clonally or emerged independently.
Methods: Multilocus sequence typing (MLST) analysis was performed for 58 colistin-resistant Acinetobacter spp. isolates; 8 isolates of A. baumannii subgroup A (Aba A), 16 of A. baumannii subgroup B (Aba B) isolates, and 34 of genomic species 13TU (GS 13TU) isolates. Results: Phylogenetic tree inferred from concatenated sequences of seven MLST loci showed a clear distinction among three Acinetobacter groups. In the MLST analysis, most colistin-resistant Acinetobacter spp. isolates showed different allele profiles in seven loci, that is, they belonged to different clones. Despite clear distinction of three Acinetobacter groups, interrelationships among three groups were not consistent in gene trees. In addition, some isolates showed incongruent clustering with their identities in some gene trees. Conclusions: MLST analysis indicated that most colistin-resistant Acinetobacter spp. isolates from Korean hospitals occurred independently. Considering increasing use of colistin and high recombination rate of Acinetobacter spp., independent but frequent emergence of colistin resistance in Acinetobacter spp. isolates is of great concern.
Harim Lee, MS1, Jae Song2, Jin Baek1, Kwan Ko3, Kyong Park4, Kyong Peck, MD5, Sook Jung4 and  K. S. Ko, None., (1)ARFID, (2)Myongji University, (3)Sungkyunkwan University School of Medecine, Suwon, Korea, Republic of, (4)Chonnam National University Medical School, (5)Samsung Medical Center, SungKyunKwan University Medical School, Seoul, Korea, Republic of

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