Antimicrobial susceptibility of microorganisms that cause urinary tract infections in pediatric patients.

Introduction: Cumulative susceptibility reports are a valuable tool for the empirical treatment of urinary tract infections, especially in the current context of increasing resistance rates. Our objective was to analyze the antimicrobial susceptibility of bacterial isolates in urine cultures of pediatric patients during a five-year period.

Methods: Retrospective study of urine cultures from 2011 to 2015. Identification and antimicrobial susceptibility tests were performed using the Vitek-2 system (BioMérieux) and categorized according to EUCAST criteria. Antimicrobial susceptibility data were analyzed by gender and age groups (neonates, 1 month to 5 years, 5-15 years) before being compared with data obtained from patients over the age of 15 years.

Results: During the study period, 17164 urine cultures were processed from 7924 patients under 16 years of age. Antimicrobial susceptibility rates in these patients were: ampicillin 36.3%, amoxicillin/clavulanic acid 75.3%, cefuroxime 83.2%, co-trimoxazole 68.9%, ciprofloxacin 85.3%, fosfomycin 85.5%, nitrofurantoin 84.4% and 3rd generation cephalosporins 89-91%. Aminoglycosides (>92%) and carbapenems (95%) maintained the highest susceptibility rates. The prevalence of ESBL-producing isolates was significantly lower in children under the age of 16 years (1.5% vs. 4.1%). In patients under the age of 16 years, Escherichia coli isolates in girls were significantly more sensitive (p<0.0001) to ampicillin (41% vs. 30%) and amoxicillin/clavulanic acid (82% vs. 72%) than in boys.

Conclusions: The compilation of cumulative susceptibility reports disaggregated by age or gender reveals significant differences. In our setting, cefuroxime may be considered the first-line empirical treatment in pediatric patients.