Urinary tract infection in small outpatient children: the influence of age and gender on resistance to oral antimicrobials

Urinary tract infection (UTI) is a common bacterial disease in small children in which treatment with antimicrobials is used. The worldwide increase of bacterial resistance to these drugs is threatening the efficacy of such treatment and may increase the risk for long-term damage. The aim of this retrospective study was to analyse the development of resistance to oral antimicrobials over a 10-year period in an unselected outpatient population of small children with first-time UTI. The patient material included 494 boys and 512 girls below 2 years of age with community acquired symptomatic UTI. Escherichia coli bacteria were isolated in 96 % of girls and 89 % of boys (p < 0.0001). The overall resistance of E. coli was 14 % to trimethoprim and below 1 % to cefadroxil and nitrofurantoin. Over the 10-year period, the trimethoprim resistance of E. coli increased from 5 to 17 % but remained unchanged to cefadroxil and nitrofurantoin. E. coli resistance to trimethoprim was related to age: 11 % below and 19 % above 9 months (p < 0.01). The increase in resistance over time and with age was found only in girls. Conclusion: The increasing resistance of E. coli to trimethoprim makes this drug less suitable for empiric treatment of UTI. Young children with UTI seem predisposed to early development of resistance. Therefore, surveillance of resistance to antimicrobials with special regard to age and gender is recommended.