Characterization of blaKPC-containing Klebsiella pneumoniae isolates detected in different institutions in the Eastern USA

J Antimicrob Chemother. 2009 Mar;63(3):427-37. doi: 10.1093/jac/dkn547. Epub 2009 Jan 20.


Background: The emergence of bla(KPC)-containing Klebsiella pneumoniae (KPC-Kp) isolates is attracting significant attention. Outbreaks in the Eastern USA have created serious treatment and infection control problems. A comparative multi-institutional analysis of these strains has not yet been performed.

Methods: We analysed 42 KPC-Kp recovered during 2006-07 from five institutions located in the Eastern USA. Antimicrobial susceptibility tests, analytical isoelectric focusing (aIEF), PCR and sequencing of bla genes, PFGE and rep-PCR were performed. Results By in vitro testing, KPC-Kp isolates were highly resistant to all non-carbapenem beta-lactams (MIC(90)s >or= 128 mg/L). Among carbapenems, MIC(50/90)s were 4/64 mg/L for imipenem and meropenem, 4/32 mg/L for doripenem and 8/128 for ertapenem. Combinations of clavulanate or tazobactam with a carbapenem or cefepime did not significantly lower the MIC values. Genetic analysis revealed that the isolates possessed the following bla genes: bla(KPC-2) (59.5%), bla(KPC-3) (40.5%), bla(TEM-1) (90.5%), bla(SHV-11) (95.2%) and bla(SHV-12) (50.0%). aIEF of crude beta-lactamase extracts from these strains supported our findings, showing beta-lactamases at pIs of 5.4, 7.6 and 8.2. The mean number of beta-lactamases was 3.5 (range 3-5). PFGE demonstrated that 32 (76.2%) isolates were clonally related (type A). Type A KPC-Kp isolates (20 bla(KPC-2) and 12 bla(KPC-3)) were detected in each of the five institutions. rep-PCR showed patterns consistent with PFGE.

Conclusions: We demonstrated the complex beta-lactamase background of KPC-Kp isolates that are emerging in multiple centres in the Eastern USA. The prevalence of a single dominant clone suggests that interstate transmission has occurred.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Typing Techniques
  • Cluster Analysis
  • DNA Fingerprinting
  • DNA, Bacterial / genetics
  • Electrophoresis, Gel, Pulsed-Field
  • Genotype
  • Humans
  • Isoelectric Focusing
  • Isoelectric Point
  • Klebsiella Infections / microbiology*
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / enzymology*
  • Klebsiella pneumoniae / isolation & purification*
  • Microbial Sensitivity Tests
  • Molecular Epidemiology
  • Sequence Analysis, DNA
  • United States
  • beta-Lactam Resistance*
  • beta-Lactamases / biosynthesis*
  • beta-Lactamases / chemistry


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • beta-Lactamases