The prevalence of plasmid-mediated quinolone resistance and ESBL-production in Enterobacteriaceae isolated from urinary tract infections Robab Azargun,1,2 Mohammad Reza Sadeghi,3 Mohammad Hossein Soroush Barhaghi,2 Hossein Samadi Kafil,2,4 Fatemeh Yeganeh,2 Mahin Ahangar Oskouee,2 Reza Ghotaslou1,2 1Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; 2Microbiology Department, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; 3Azad University of Macu, Macu, Iran; 4Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Introduction: β-lactam and fluoroquinolone antibiotics are usually used for the treatment of urinary tract infections (UTIs). The aim of this study was to determine the prevalence of plasmid-mediated quinolone resistance (PMQR) and extended spectrum β-lactamases (ESBLs) in Enterobacteriaceae isolated from UTIs. Materials and methods: Two hundred and nineteen samples of Enterobacteriaceae isolated from UTIs were collected in the Northwest of Iran. Antimicrobial susceptibility testing was determined by the disk diffusion method. ESBLs were detected by the double-disk test. ESBL and PMQR-encoding genes were screened using the polymerase chain reaction. Results: The rate of resistance to moxifloxacin, nalidixic acid, gatifloxacin, ofloxacin, ciprofloxacin, and levofloxacin in ESBL-producing isolates was 89.3%, 88%, 84%, 80%, 78.7%, and 73.3%, respectively. PMQR-producing Enterobacteriaceae isolates were identified in 67 samples (89.1%). The most prevalent PMQR genes were aac (6′)-Ib-cr 120 (68.6%) followed by oqxB 72 (41.1%), oqxA 59 (33.7%), qnrB 36 (20.6%), qnrS 33 (18.9%), qnrD 19 (10.9%), qepA 13 (7.4 %), qnrA 10 (5.7%), and qnrC 9 (5.1%). There was a strong association between PMQR genes and blaCTX-M-15 and blaTEM-116 and other ESBL genes. Conclusion: High resistance rates were detected to quinolones among ESBL-producing isolates from UTIs. There is a high prevalence of PMQR genes in Enterobacteriaceae in Azerbaijan and Iran, and the most common PMQR is aac(6′)-Ib-cr. There is a significant association between PMQR and ESBL-producing isolates. Keywords: Enterobacteriaceae, ESBLs, plasmid-mediated quinolone resistance, urinary tract infections