Research Support, Non-U.S. Gov't
- Molecular Analysis of a Prolonged Spread of Klebsiella pneumoniae Co-producing DHA-1 and SHV-12 β-Lactamases
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Young Kyung Yoon , Hye Won Cheong , Hyunjoo Pai , Kyoung Ho Roh , Jeong Yeon Kim , Dae Won Park , Jang Wook Sohn , Seung Eun Lee , Byung Chul Chun , Hee Sun Sim , Min Ja Kim
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J. Microbiol. 2011;49(3):363-368. Published online June 30, 2011
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DOI: https://doi.org/10.1007/s12275-011-0491-9
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Abstract
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The study investigated molecular mechanisms for prolonged nosocomial spread of multidrug-resistant Klebsiella pneumoniae co-producing plasmid-mediated AmpC β-lactamase DHA-1 and extended-spectrum β-lactamase SHV-12. Forty-eight clinical isolates of K. pneumonia, resistant to the extended-spectrum cephalosporins, were collected in a 750-bed university hospital over a year. The isolates were characterized for PCR-based β-lactamase genotypes, isoelectric focusing and pulsed-field gel electrophoresis (PFGE) profiles. Resistance transfer was performed by plasmid conjugation and confirmed by a duplex-PCR and Southern hybridization. On β-lactamase typing, the strains producing only the DHA-1 enzyme (n=17) or co-producing DHA-1 and SHV-12 enzymes (n=15) were predominant. Judging from a one year-distribution of PFGE profiles, the co-producer was spread primarily with single clonal expansion of the PFGE-type A with subtypes (n=14), whereas the strains producing only DHA-1 enzyme were spread simultaneously with the PFGE-type A (n=11) and other PFGE types (n=6). Transconjugants of the co-producers were confirmed to harbor either both blaDHA-1 and blaSHV-12 or only the blaDHA-1. In conclusion, this study indicated that the persistent nosocomial spread of multidrug-resistant K. pneumoniae strains was primarily associated with expansion of a clone harboring both the blaDHA-1 and blaSHV-12 or the blaDHA-1 only, and to a lesser extent with the horizontal transfer of the resistant plasmids. Our observations have clinical implication for the control and prevention of nosocomial dissemination of multidrug-resistant K. pneumoniae strains.