Fecal colonization of Enterobacteriaceae carrying plasmid-mediated quinolone resistance determinants in Korea

Microb Drug Resist. 2011 Dec;17(4):507-12. doi: 10.1089/mdr.2011.0040. Epub 2011 Aug 10.


The aims of the current study were to investigate the prevalence and molecular characteristics of plasmid-mediated quinolone resistance (PMQR) genes from colonizing fecal organisms and to compare the incidence and subtype of these genes according to bacterial species and hospital at five tertiary-care hospitals in Korea. A total of 500 nonduplicated clinical isolates of Enterobacteriaceae were obtained from fecal specimens at five tertiary-care hospitals between March and May 2008. The PMQR genes (qnrA, qnrB, qnrS, aac(6')-Ib-cr, and qepA) were amplified by PCR and confirmed by direct sequencing of the PCR products. A total of 83 (16.6%) qnr-positive isolates were detected. The prevalence rates of qnrA, qnrB, and qnrS were 1.4%, 13.6%, and 1.6%, respectively. The species distributions of qnrB-positive isolates were Klebsiella pneumoniae (37/109; 33.9%), Citrobacter freundii (10/34; 29.4%), Citrobacter braakii (8/13; 61.5%), and Escherichia coli (8/275; 2.9%). Sixteen subtypes of qnrB were detected, including seven novel variants. The prevalences of aac(6')-Ib-cr and qepA were 15.6% (n=78) and 0.6% (n=3), respectively. The aac(6')-Ib-cr gene was detected in 39 (47.0%) of 83 qnr-positive isolates and 39 (9.4%) of 417 qnr-negative isolates There was one qepA variant containing a novel mutation (Ala231Val). The prevalence of PMQR genes was high in Enterobacteriaceae from stool specimens in Korea, and there was a close relation between qnr and aac(6')-Ib-cr.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics
  • Conjugation, Genetic
  • Drug Resistance, Bacterial / genetics*
  • Enterobacteriaceae / classification
  • Enterobacteriaceae / drug effects
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / isolation & purification*
  • Enterobacteriaceae Infections / epidemiology*
  • Enterobacteriaceae Infections / microbiology
  • Feces / microbiology*
  • Hospitals, University
  • Humans
  • Microbial Sensitivity Tests
  • Plasmids / genetics*
  • Polymerase Chain Reaction
  • Quinolones / pharmacology*
  • Republic of Korea / epidemiology


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Quinolones