Urinary tract infections caused by extended-spectrum beta-lactamase （ESBL）-producing bacteria are increasing worldwide. However, since the start of the SARS-CoV-2 pandemic in 2020, the proportion of ESBL-producing E. coli has changed. This retrospective study included patients who were hospitalized in the pediatric department of Matsue Red Cross Hospital with UUTI caused by E. coli. Medical and hospital records were reviewed to assess patient characteristics, antimicrobial use density, and days of antibiotic therapy at the hospital from January 1, 2016, to December 31, 2022. Urine sample analyses showed that the proportion of ESBL-producing E. coli decreased significantly in 2020 to 2022. Antimicrobial use density and days of therapy of oral third-generation cephems was significantly correlated with the proportion of UUTI caused by ESBL-producing E. coli in pediatric patients. Effective hygiene measures and appropriate use of antibiotics especially, oral third-generation cephems, are effective for reducing the incidence of ESBL-producing bacterial infections.