A Long-Term Low-Frequency Hospital Outbreak of KPC-producing Klebsiella Pneumoniae Involving Intergenus Plasmid Diffusion and a Persisting Environmental Reservoir

PLoS One. 2013;8(3):e59015. doi: 10.1371/journal.pone.0059015. Epub 2013 Mar 11.

Abstract

Background: To study the molecular characteristics of a long-term, low frequency outbreak of bla KPC-2 in a low prevalence setting involving the hospital environment.

Methodology/principal findings: KPC-producing bacteria were screened by selective chromogenic agar and Real-Time PCR. The presence of antibiotic resistance genes was ascribed by PCRs and subsequent sequencing, and the KPC-producing isolates were phylogenetically typed using PFGE and multi-locus sequence typing. Bla KPC-2-plasmids were identified and analysed by S1-nuclease-PFGE hybridization and PCR based replicon typing. A ∼97 kb IncFII plasmid was seen to carry bla KPC-2 in all of the clinical isolates, in one of the isolates recovered from screened patients (1/136), and in the Klebsiella pneumoniae and Enterobacter asburiae isolates recovered from the environment (sinks) in one intensive care unit. The K. pneumoniae strain ST258 was identified in 6 out of 7 patients. An intergenus spread to E. asburiae and an interspecies spread to two different K. pneumoniae clones (ST27 and ST461) of the bla KPC-2 plasmid was discovered. K. pneumoniae ST258 and genetically related E. asburiae strains were found in isolates of both human and environmental origins.

Conclusions/significance: We document a clonal transmission of the K. pneumoniae ST258 strain, and an intergenus plasmid diffusion of the IncFII plasmid carrying bla KPC-2 in this outbreak. A major reservoir in the patient population could not be unveiled. However, the identification of a persisting environmental reservoir of strains with molecular determinants linked to human isolates, suggests a possible role of the environment in the maintenance of this long-term outbreak.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Bacterial Proteins / biosynthesis
  • Cross Infection / epidemiology*
  • Disease Outbreaks
  • Disease Reservoirs / microbiology*
  • Drug Resistance, Bacterial / genetics
  • Electrophoresis, Gel, Pulsed-Field
  • Humans
  • Klebsiella Infections / epidemiology*
  • Klebsiella pneumoniae / classification*
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / genetics*
  • Klebsiella pneumoniae / isolation & purification
  • Microbial Sensitivity Tests
  • Multilocus Sequence Typing
  • Plasmids / genetics*
  • Risk Factors
  • beta-Lactamases / biosynthesis

Substances

  • Bacterial Proteins
  • beta-Lactamases
  • carbapenemase

Grant support

The study was supported by a fellowship from SÃ ¸rlandet Hospital HF and a research grant from the Northern Norway Regional Health Authority Medical Research Programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.