Objective Urinary tract infections (UTIs) caused by resistant organisms are increasing which poses challenges when selecting empirical antimicrobial therapy. The aim of this study is to determine risk factors for multiresistant Escherichia coli UTIs in children.

Design We included all reported urinary isolates from a children’s hospital collected between January 2010 and June 2013. Patients who had multiresistant E. coli UTIs were identified and a retrospective review of medical records performed. Patient-specific clinical and demographic factors were compared with age-matched and gender-matched controls with non-multiresistant E. coli UTIs. Univariable and multivariable statistical analysis were performed to determine significant risk factors for multiresistant organism E.coli UTIs.

Results In total, there were 2692 positive urine cultures, 1676 (62.3%) from 1169 patients were E. coli. Multiresistant E. coli was isolated from 139 (8.3% of all E. coli) cultures in 99 patients. Thirteen incomplete medical records were excluded, leaving 86 patients, matched with 86 controls. In multivariable regression, the only significant risk factor was antibiotic use in the previous month (adjusted OR 3.0, 95% CI 1.4 to 6.2), but not previous hospital admission (adjusted OR 1.4, 95% CI 0.6 to 2.9), being an inpatient at the time of diagnosis (adjusted OR 2.4, 95% CI 0.8 to 7.4) and previous instrumentation (adjusted OR 1.0, 95% CI 0.4 to 2.4).

Conclusions This is the first case–control study to examine multiresistant UTI in Australian children. Clinicians should be judicious in the use of antibiotics in treatment and prophylaxis of UTIs. In children presenting with UTI and recent antibiotic exposure, amoxicillin-clavulanic acid appears to be an appropriate empiric antibiotic choice in our population.