Prevalence of Plasmid‐Mediated Quinolone Resistance Genes in Escherichia coli Isolates From Colonic Biopsies of Iranian Patients With Inflammatory Bowel Diseases: A Cross‐Sectional Study

ABSTRACT Background and Aims Emerging evidence suggests that ciprofloxacin and other quinolones can be effectively used as adjuncts to immunosuppressive therapy in managing inflammatory bowel disease (IBD). Clinical isolates of Enterobacterales frequently exhibit quinolone resistance. Additionally, increased IBD severity has been linked to the proliferation of Enterobacterales in the gut. This study aimed to explore the frequency of fluoroquinolone resistance and the presence of associated resistance genes in Escherichia coli isolates obtained from intestinal biopsies of patients with IBD in Iran. Methods In this research, we conducted a study that involved the isolation and examination of E. coli bacteria from inflamed ileal and/or colonic tissues of patients diagnosed with IBD, specifically ulcerative colitis (UC) and Crohn's disease (CD), during colonoscopy procedures. We collected demographic and clinical information from the patients. To identify E. coli strains that were resistant to quinolone antibiotics, we performed both phenotypic and molecular analyses. Results From the colonic and ileal biopsies of 121 patients with IBD, we isolated 107 unique strains of E. coli. Among these strains, 18 (16.8%) were derived from patients with CD, and 89 (83.2%) came from those with UC. Antimicrobial susceptibility tests revealed that 61 out of 107 isolates (57%) of the isolates showed phenotypic resistance to at least one type of quinolone. Additionally, plasmid‐mediated quinolone resistance (PMQR) genes, specifically oqxA, oqxB, and qnrS were detected in the E. coli strains linked to both UC and CD. Notably, there was a significant positive correlation observed between intestinal colonization by ciprofloxacin‐resistant E. coli and the patients' history of extended ciprofloxacin antibiotic therapy. Conclusion Our results reveal that a significant number of patients with IBD carry quinolone‐resistant E. coli. This colonization may pose a risk factor that could affect disease progression and contribute to potential complications.