Trends in antibiotic susceptibility in childhood acute urinary tract infections: a single-center comparison across a 10-year interval in Korea

Purpose: Acute urinary tract infection (UTI) is one of the most common bacterial infections in children and a major cause of antibiotic use. Increasing antimicrobial resistance has raised concerns regarding the appropriate selection of empirical antibiotics in pediatric UTIs. Methods: We retrospectively analyzed 571 children diagnosed with culture-confirmed acute UTI at a single tertiary center be - tween 2015 and 2020 and compared the findings with data from a previous study conducted at the same institution between 2003 and 2008. Uropathogen distribution, antibiotic susceptibility patterns, extended-spectrum β -lactamase (ESBL) prevalence, and imaging findings were evaluated. Results: Gram-negative organisms accounted for 98.2% of UTIs, with Escherichia coli being the most common pathogen (89.1%). Compared with 2003–2008, antibiotic susceptibility significantly decreased during 2015–2020 for several commonly used agents in both the overall bacterial population and E. coli isolates. The prevalence of ESBL-producing organisms increased markedly. No significant association was observed between microbiological findings and imaging abnormalities. Conclusions: Antibiotic resistance in pediatric UTIs increased significantly over an approximately 10-year period within the same institutional setting. These findings highlight evolving antimicrobial resistance and underscore the importance of continuous local surveillance to guide empirical antibiotic selection.