Comparative Analysis of ESBL Phenotypes and Antimicrobial Resistance in Escherichia coli Associated with Urinary Tract Infections and in Commensal Strains

Escherichia coli is a genetically versatile organism capable of thriving in diverse environments, acting as a commensal in the intestine or as a pathogen in the urinary tract. E. coli causing urinary tract infections has acquired genes that enable it to colonize the urinary tract, survive immune response, and resist antimicrobials. In this study, we investigated the association between the ESBL (Extended Spectrum Beta Lactamase) phenotype and other antimicrobial resistances in E. coli associated with urinary tract infections (UTI-E. coli; n = 1,139) and compared them with commensal E. coli strains (n = 405) isolated from human fecal samples in the same communities and during the same period. Among UTI-E. coli strains, 16.9% were ESBL producers compared to 7.6% in commensal strains, and resistance to other antimicrobials was also significantly higher in UTI-E. coli. These results suggest that many UTI-E. coli and commensal E. coli lineages have been subjected to distinct antimicrobial pressures over time.