Session: Poster Session: Plasmid-Mediated Quinolone Resistance
Tuesday, October 28, 2008: 12:00 AM
Room: Hall C
Background: Three groups of plasmid-mediated quinolone resistance have been identified to date. Qnr proteins encoded by qnrA, -B, -S genes protect the DNA gyrase by inhibition from quinolones, and an aminoglycoside acetyltransferase encoded by the aac(6’)-cr gene confers reduced susceptibility to ciprofloxacin and norfloxacin. Recently, a plasmid-mediated efflux pump, qepA gene, was also found in an E. coli. In this study, we examined the presence of qepA in E. coli clinical isolates from Korea and analyzed the genetic structure of plasmid adjacent to qepA gene. Methods: A total of 621 non-duplicate E. coli isolates were collected from blood cultures in Asan Medical Center, Seoul, Korea between January 2006 and September 2007. Screening for the qepA was carried out by PCR amplification with specific primers. To determine whether the qepA-positive plasmid is transferable, conjugation experiments were done with azide-resistant E. coli J53 as the recipient. RAPD fingerprinting was performed to assess the clonal relationship. Results: Of 621 E. coli clinical isolates, qepA gene was detected in 4 isolates (0.6%). Conjugation experiments revealed that all qepA genes were successfully transferred and conferred resistance to the hydrophilic quinolones such as norfloxacin and ciprofloxacin. The qepA gene was located in a part of transposable element of IS26. Three isolates harboring qepA were associated with β-lactamase genes, CTX-M-9 and/or TEM-1. The RAPD patterns showed that the four isolates were clonally unrelated. Conclusions: This is the first report of the occurrence of E. coli clinical isolates carriying qepA gene in Korea. The rate of qepA gene was lower than other two groups of plasmid-mediated quinolone resistance (aac(6’)-cr and qnr genes) in E. coli from Korea.