Structural diversity of class 1 integrons and their associated gene cassettes in Klebsiella pneumoniae isolates from a hospital in China

PLoS One. 2013 Sep 30;8(9):e75805. doi: 10.1371/journal.pone.0075805. eCollection 2013.

Abstract

Background: Klebsiella pneumoniae strains carrying class 1 integrons are becoming more common worldwide, and their role in the dissemination of drug resistance is significant. The aim of this study was to characterize the structural diversity of class 1 integrons and their associated gene cassettes in K. pneumoniae isolates from hospital settings.

Methodology/principal findings: We analyzed a total of 176 K. pneumoniae isolates in a tertiary-care hospital in Beijing, China for the period of November 1, 2010-October 31, 2011. The presence of class 1 integrons and gene cassettes was analyzed by PCR and sequencing. The prevalence of class 1 integrons was 51.1% (90/176). Fourteen different gene cassettes and 10 different gene cassette arrays were detected. dfrA and aadA cassettes were predominant and cassette combination dfrA1-orfC was most frequently found (13.6%, 24/176). Strong association between resistance to a variety of drugs (both phenotypes and the associated genes) and the presence of class 1 integrons was observed. In addition, we also identified an association between some previously identified prevalent sequence types (such as ST11, ST15, ST147, ST562, and ST716) and the presence of class 1 integrons.

Conclusions/significance: Data from this study demonstrated that class 1 integrons are highly diverse and are associated with a variety of drug resistance phenotypes, drug resistance genes, as well as genotypes among K. pneumoniae isolates. Continuous monitoring of gene cassettes in class 1 integrons is warranted to improve the understanding and control of drug resistance among hospital settings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • China / epidemiology
  • Computational Biology
  • Cross Infection / epidemiology*
  • Cross Infection / genetics*
  • DNA Primers / genetics
  • Drug Resistance, Bacterial / genetics*
  • Humans
  • Integrons / genetics*
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / genetics*
  • Klebsiella pneumoniae / genetics*
  • Klebsiella pneumoniae / isolation & purification
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Sequence Analysis, DNA

Substances

  • DNA Primers

Grants and funding

This work was supported by the National Basic Research Program of China (973 Program, 2012CB518700), the key project of the Ministry of Health and the Ministry of Science and Technology, China (2013ZX10003006), the Key Program of the Chinese Academy of Sciences (KSZD-EW-Z-006 and KSCX2-EW-J-6), and the Merieux Research Grant program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.