OBJECTIVES: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.

Kim MH, et al. Yonsei Med J. 2011 Mar;52(2):276-281. http://dx.doi.org/10.3349/ymj.2011.52.2.276

Park DC, et al. Ann Lab Med. 2019 Nov;39(6):537-544. https://doi.org/10.3343/alm.2019.39.6.537

Kim MH, et al. Yonsei Med J. 2010 Sep;51(5):768-774. http://dx.doi.org/10.3349/ymj.2010.51.5.768

Yang HY, et al. Yonsei Med J. 2009 Dec;50(6):764-770. http://dx.doi.org/10.3349/ymj.2009.50.6.764