Abstract
The emergence of multidrug-resistant Escherichia coli (MDR E. coli), particularly enteropathogenic E. coli, is closely associated with therapeutic interventions for irritable bowel syndrome (IBS) and ulcerative colitis (UC) in clinical practice. However, a comprehensive characterization of their resistome differences remains limited. Exploring their resistance profiles and virulence gene repertoires is crucial for informing improved treatment strategies and controlling the dissemination of MDR E. coli in healthcare settings. Here, we analyzed 70 E. coli strains isolated from a single-center, case-control cohort enrolled between 2022 and 2023 at a tertiary care hospital in Beijing, China. Through integrated phenotypic and genomic approaches, we investigated their antimicrobial resistance (AMR) patterns and transmission dynamics. These strains exhibited high resistance to sulfonamides (34.3 %) and fluoroquinolones (32.9 %) in general. Incremental trends in β-lactam resistance were observed in the IBS-D and UC groups compared to the HC group, reflecting both phenotypic resistance and the presence of ESBL genes. Significant intergroup differences in the prevalence of β-lactam resistance gene bla (TEM-1B), rifamycin resistance gene ARR-3, and ExPEC-related nutritional/metabolic factors (e.g. chuA, chuU, iroD, iroE, kpsM) were observed. Notably, the co-existence of bla (CTX-M-55) and tet(X4) was first identified in IBS-D patients. The emergence of high-risk ST10, ST1193, and ST131 clones occurred in IBS-D and UC patients. Positive correlations were observed between the number of antibiotic resistance genes, virulence factor genes, and antibiotic usage history. This study underscores escalating AMR and virulence trends across patient groups and highlights the urgent need for tailored antimicrobial stewardship in managing IBS-D and UC.