Discordance between antibiotic therapy and recurrent urinary tract infections in young children with third-generation cephalosporin-resistant infections

Abstract

Background: Third-generation cephalosporins remain the empirical mainstay for pediatric urinary tract infections (UTIs) in Korea, yet the resistance rate now approaches 30%, thereby threatening treatment effectiveness. Purpose: To determine whether completing a cephalos-porin regimen, despite in vitro resistance, increases early UTI recurrence rates. Methods: We retrospectively reviewed the cases of child-ren aged <24 months with their first Gram-negative UTI admitted in 2020-2024. Three exposure groups were de-fined: susceptible isolates treated with a third-generation cephalosporin; resistant isolates that received >= 5 days of antibiotics to which the isolated organism was susceptible (concordant); and resistant isolates that received <5 days of appropriate antibiotic therapy (discordant). The primary outcome was UTI recurrence within 2 months. Kaplan-Meier curves were generated, while multivariate Cox models adjusted for age, fever, acute cortical defects, and kidney anomalies were used to estimate hazard ratios (HRs). Results: Among 989 children (mean age, 4.4 months), 424 (42.9%) had cefotaxime-resistant isolates; of them, 76 (17.9%) received concordant therapy and 348 (82.1%) received discordant therapy. The overall 2-month re-currence rate was 15.4% (95% confidence interval [CI], 13.0-17.7). Compared to the susceptible group, the concor-dant group did not show a significantly different relapse rate (adjusted HR [aHR], 1.09; 95% CI, 0.67-1.78), whereas the discordant group demonstrated an increased recur-rence risk (aHR, 1.42; 95% CI, 1.08-1.86). An analysis of culture-confirmed recurrence yielded similar findings (discordant therapy aHR, 1.82; 95% CI, 1.29-2.56). No signi-ficant differences were observed when the analysis was restricted to febrile recurrence. Conclusion: Completing a third-generation cephalospo-rin course when isolates are not susceptible to third-generation cephalosporins can increase early UTI recur-rence rates in Korean children. Reviewing susceptibility on day 5 and switching to an active oral agent may reduce recurrence and limit unnecessary broad-spectrum anti-biotic exposure.