Clinical Outcomes of Non-carbapenem Treatment for Urinary Tract Infections Caused by Extended-spectrum β-lactamase-producing Escherichia coli

Purpose: The purpose of this study was to investigate the clinical outcomes of non-carbapenem treatment for urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) in young children. Methods: We retrospectively reviewed the medical records of children under 2 years of age who were diagnosed and treated for UTIs caused by ESBL-producing E. coli from September 2014 to March 2020. Results: Forty-three children under 2 years of age were treated with non-carba-penem antimicrobials for UTIs caused by ESBL-producing E. coli without bloodstream infections. The overall clinical and microbiological success rates for empirical antimicrobial treatment were 90.7% and 97.7%. Three of the patients (7.0%) ex-perienced a relapse of UTI within a month. An in vitro susceptibility test showed that two patients were sensitive and one was resistant to the antimicrobial trea-tments. Furthermore, there were no significant differences in the time to deferve-scence, clinical success, microbiological success, and relapse rate between the susceptible (n=13) and non-susceptible groups (n=30). Conclusion: In this study, the overall relapse rate of patients treated with non-carbapenem antimicrobials was 7.0%. The patients showed high success rates in the clinical and microbiological responses to the non-carbapenems regardless of the results of the in vitro antimicrobial susceptibility test. These results provide evidence that non-carbapenems may be viable alternative treatments for UTIs caused by ESBL-producing E. coli.