title: Prevalence of plasmid-mediated quinolone resistance genes among ciprofloxacin-nonsusceptible Escherichia coli and Klebsiella pneumoniae isolated from blood cultures in Korea.
abstract: OBJECTIVE
  To analyze the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants in ciprofloxacin-nonsusceptible Escherichia coli and Klebsiella pneumoniae isolated from patients at a tertiary care hospital in Korea.
  
  
  METHODS
  A total of 102 nonduplicate isolates of ciprofloxacin-intermediate or ciprofloxacin-resistant E coli (n=80) and K pneumoniae (n=22) from blood cultures were obtained. The qnr (qnrA, qnrB, qnrS), aac(6')-Ib-cr, qepA and oqxAB genes were detected using polymerase chain reaction (PCR) and confirmed using direct sequencing. To determine whether the PMQR-positive plasmid was horizontally transferable, conjugation experiments were performed.
  
  
  RESULTS
  Of the 102 isolates, 81 (79.4%) had one or more PMQR genes; these consisted of 59 (73.8%) E coli and 22 (100%) K pneumoniae isolates. The qnr genes were present in 15 isolates (14.7%): qnrB4 was detected in 10.8% and qnrS1 was detected in 3.9%. The aac(6')-Ib-cr, qepA and oqxAB genes were detected in 77.5%, 3.9% and 10.8%, respectively. In conjugation experiments, PMQR genes were successfully transferred from seven (8.6%) isolates. The range of minimum inhibitory concentrations of ciprofloxacin for these seven transconjugants increased to 0.5 mg/L to 1 mg/L, which was 16- to 33-fold that of the recipient E coli J53 bacteria.
  
  
  CONCLUSIONS
  PMQR genes were highly prevalent among ciprofloxacin-nonsusceptible E coli and K pneumoniae from blood cultures in the authors' hospital. Therefore, it is necessary to monitor for the spread of PMQR genes of clinical isolates and to ensure careful antibiotic use in a hospital setting.
authors.affiliation: Department of Laboratory Medicine, Kosin University College of Medicine, Busan and Department of Medicine;
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Yang
authors.affiliation: Department of Biomedical Science, Graduate School, Kyung Hee University;
authors.forename: You Sun
authors.initials: YS
authors.lastname: Nam
authors.affiliation: Department of Laboratory Medicine, Kyung Hee University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hee Joo
authors.initials: HJ
authors.lastname: Lee
keywords: Plasmid-mediated quinolone resistance genes; aac(6′)-Ib-cr; oqxAB; qepA; qnr