Introduction & Objective: Widespread use of antibiotics has caused bacterial resistance to them. Plasmids that develop resistance to quinolones and fluoroquinolones are one of the major problems in the treatment of urinary tract infections that are scattered in Escherichia coli isolates worldwide. The aim of this study was to investigate the phenotypic resistance and detection of some quinolone resistance plasmid genes in Escherichia coli isolated from human urinary tract infection (UTI) in Mashhad. Materials and Methods: In this study, 99 E.coli isolates were collected from Mashhad hospitals in 2018-19. After identification by biochemical methods and then antibiogram with antibiotic discs: ciprofloxacin, Neurofloxacin, difloxacin, anrofloxacin, flomcoquine, and nalidixic acid were evaluated by disk diffusion method for resistance. Genomes (qnrA, qnrB, qnrS) were identified by multiplex PCR. Results: In this study, from 99 isolates, 81 (81.8%).were resistant to nalidixic acid. Then, Flomecoin 78 (78.7%), Difloxacin 69 (69.6%), Norfloxacin 68 (68.6%), Enrofloxacin 67 (67.6%), and Ciprofloxacin 67 (67.6%) were resistant. Identification of the related genes showed that the highest gene belonged to the qnrB gene 25 (25.2%), followed by the qnrS gene 12 (12.1%) and the lowest gene belonged to the qnrA gene in 7 (7%). Conclusion: The results of the present study showed that the efficacy of quinolones as one of the most effective drugs in the treatment of urinary tract infections has been significantly reduced. This study showed that the distribution of resistance plasmid genes plays an important role in this matter and it can spread rapidly among bacteria.

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