Background/Objectives: Escherichia coli is the predominant pathogen in community-onset urinary tract infections (UTIs) requiring hospitalization. This study characterized antimicrobial resistance profiles, biofilm formation, extended-spectrum β-lactamase (ESBL) gene distribution, and phylogenetic background of E. coli isolates from hospitalized UTI patients in Western Mexico. Methods: Seventy isolates (September 2023–September 2024) underwent susceptibility testing (CLSI M100, 35th edition), multiplex PCR for blaTEM, blaCTX-M, and blaSHV genes, crystal violet biofilm quantification, and Clermont quadruplex PCR phylotyping. Associations were evaluated by Fisher’s exact test with Benjamini–Hochberg FDR (BH-FDR) correction. Results: ESBL phenotype and MDR were detected in 57.1% and 58.6% of isolates. After BH-FDR correction, ESBL production was significantly associated with amikacin (OR = 5.55; 95% CI: 1.80–18.74; q = 0.002) and TMP-SMX non-susceptibility (OR = 3.00; 95% CI: 1.02–9.23; q = 0.036); ciprofloxacin non-susceptibility was linked to MDR status (OR = 7.21; 95% CI: 1.28–75.66; q = 0.017) but not ESBL phenotype. Biofilm was detected in 77.1% of isolates. blaTEM predominated among ESBL producers (85.0%). Phylogroup B2 (51.4%) was inversely associated with recurrent UTI on both univariate (OR = 0.17; 95% CI: 0.03–0.73; p = 0.008) and adjusted analysis (adjusted OR = 0.19; 95% CI: 0.05–0.81; p = 0.025). Phylogroup C (22.9%) exhibited the highest MDR prevalence (81.3%) and the highest biofilm formation rate among phylogroups (87.5%). Conclusions: The high prevalence of ESBL-producing and MDR E. coli, combined with an unexpected predominance of blaTEM, reveals a distinctive local resistance landscape diverging from regional trends. The inverse association of phylogroup B2 with recurrence and TMP-SMX resistance reinforces the clinical value of phylogenetic surveillance in guiding UTI management strategies.
Zepeda-Gutiérrez et al. (2026) studied this question.