Etiology and Selected Multidrug-Resistance Patterns in Urinary Bacterial Isolates: A Comparative Analysis of Outpatients and Inpatients at a Tertiary Hospital in Mexico City.

Antimicrobial resistance poses a critical challenge to global public health. Urinary tract infections are one of the leading causes of morbidity in Mexico. This study aimed to identify the most prevalent bacterial pathogens in urinary bacterial isolates and to determine their antimicrobial and selected multidrug-resistance pattern profiles in outpatient and inpatient isolates at a tertiary care hospital in Mexico City. In this retrospective laboratory-based surveillance study, a census of 3434 urine samples collected between January and December 2023 was analyzed. Bacterial identification and antimicrobial susceptibility testing were performed using a VITEK 2 XL automated system. Escherichia coli was the predominant uropathogen in both groups, followed by Enterococcus spp. and Klebsiella spp. A significant disparity was observed in the resistance profiles: E. coli resistance to third-generation cephalosporins and fluoroquinolones was higher in inpatient isolates than in outpatient isolates. The selected multidrug-resistance patterns were generally higher in the inpatient isolates than in the outpatient isolates. Although common enteric pathogens with lower resistance levels predominated in the outpatient isolates, inpatient isolates required coverage targeting higher resistance. These findings reflect the need to tailor the treatment to the patients' clinical context, launch awareness campaigns for the strategic use of antibiotics, and strengthen epidemiological surveillance.