Urinary tract infections (UTIs) are among the leading causes of hospital admissions and antibiotic prescriptions in public health systems, particularly among women and older adults. Rising resistance to first-line antibiotics, such as trimethoprim-sulfamethoxazole and fluoroquinolones, is concerning. This study analyzed the microbiological profile and antimicrobial susceptibility patterns of community-acquired UTIs in a major city in southeastern Brazil, aiming to inform clinical management and rational antibiotic use.

A cross-sectional study was conducted using laboratory records of urine cultures collected in June 2024 from nine municipal regions. Positive samples underwent antimicrobial susceptibility testing. Hospitalization data due to Ambulatory Care-Sensitive Conditions (ACSC) were also reviewed.

In 2024, UTIs were the leading cause of ACSC hospitalizations in the municipality, accounting for 835 admissions across seven monitored hospitals. Among 2,009 outpatient urine samples analyzed, 213 (10.6%) showed bacterial growth. Escherichia coli was the predominant pathogen (156 isolates; 74.3%), followed by Klebsiella pneumoniae (26 isolates; 12.2%). High resistance rates were observed for ampicillin (54.5%), trimethoprim-sulfamethoxazole (27.5%), norfloxacin (25.9%), amoxicillin-clavulanate (25.8%), and ciprofloxacin (24.2%). Nitrofurantoin showed a low resistance rate (2.4%). Parenteral antimicrobials often used in severe cases, such as gentamicin and ceftriaxone, retained good activity despite moderate resistance (12.4% and 7.1%, respectively).

The high resistance rates to widely used first-line agents discourage the empirical use of trimethoprim-sulfamethoxazole, norfloxacin, and amoxicillin-clavulanate for initial therapy. The analysis supports nitrofurantoin as the preferred first-line agent in the municipal treatment protocol for uncomplicated UTI.