Urinary tract infections (UTIs) are among the most frequent bacterial infections worldwide, affecting about 150 million people annually. Due to the anatomic characteristics of the genitourinary tract, women are more susceptible to UTIs than men. Etiologic agents are diverse and may include Gram-negative and Gram-positive bacteria and, in some cases, yeasts. This study aimed to identify the main causative agents and evaluate the antimicrobial resistance profile in community-acquired UTIs in residents of Porto Alegre and the metropolitan area. Retrospective, quantitative study based on urine culture results from a large laboratory in the metropolitan region of Porto Alegre. All outpatient urine cultures performed in 2024 were included, totaling 105,811 tests. Of all urine cultures, 22.17% were from male and 77.83% from female patients. The positivity rate was 12.3%, predominantly in females (90.22% of positive cultures). Escherichia coli was the most frequently isolated organism (65.55% of positive cultures), followed by Klebsiella pneumoniae (10.23%), Proteus mirabilis (4.2%) and Staphylococcus saprophyticus (3.75%). Among E. coli isolates, the highest in vitro resistance rates were to ampicillin (45.3%) and trimethoprim-sulfamethoxazole (29.5%). A similar resistance pattern was observed in K. pneumoniae and P. mirabilis isolates. Regarding resistance mechanisms, carbapenemase production was detected in 126 of 10,838 enterobacterales isolates, more frequently in K. pneumoniae , with 94 KPC-producing and 24 metallo-β-lactamase–producing isolates. The main microorganisms causing UTIs have shown increasing resistance to first-line antimicrobials such as ampicillin and trimethoprim-sulfamethoxazole. Therefore, updated epidemiological studies are crucial to ensure effective empirical therapy protocols and minimize therapeutic failures.
Zanatta et al. (Sun,) studied this question.