Colistin Resistance and Extensive Genetic Variations in PmrAB and PhoPQ in<i>Klebsiella Pneumoniae</i>Isolates from South Korea

초록

We investigated the colistin resistance ofKlebsiella pneumoniaeblood isolates from South Korea. Among 252K. pneumoniaeisolates, only 11 (4.4%) demonstrated colistin resistance, of which, one was resistant to all antibiotics but tigecycline. Multilocus sequence typing analysis revealed ten sequence types among the 11 colistin-resistant isolates, indicating independent occurrence of colistin resistance inK. pneumoniae. To understand the mechanism of colistin resistance, amino acid variations in PmrAB, PmrD, PhoPQ, and MgrB were investigated. Amino acid substitutions were identified in all the colistin-resistantK. pneumoniaeisolates. Particularly, extensive alterations in the genes associated with colistin resistance were shared in four colistin-resistant isolates, suggesting recombination between these genes of unrelated isolates. Our results suggest that genetic recombination is responsible for colistin resistance in someK. pneumoniaeisolates.

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