Molecular analysis of a prolonged spread of Klebsiella pneumoniae co-producing DHA-1 and SHV-12 β-lactamases

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, Ja Kim Min

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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 cepha-losporins, 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=ll) 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.

Original languageEnglish
Pages (from-to)363-368
Number of pages6
JournalJournal of Microbiology
Issue number3
Publication statusPublished - 2011 Jun 1



  • DHA-1
  • Klebsiella pneumoniae
  • plasmid
  • SHV-12
  • spread

ASJC Scopus subject areas

  • Microbiology
  • Applied Microbiology and Biotechnology

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