The goal was to determine the association between short-duration (≤3 days) and long-duration (≥4 days) intravenous antibiotic therapy and treatment failure in a cohort of young infants hospitalized with urinary tract infections (UTIs).


We conducted a retrospective cohort study of infants <6 months of age who were hospitalized with UTIs between 1999 and 2004 at 24 children's hospitals in the Pediatric Health Information System. Our main model adjusted for all covariates, propensity scores, and clustering according to hospital to evaluate the effect of short versus long courses of inpatient intravenous antibiotic therapy on treatment failure, defined as readmission because of UTI within 30 days.


Of the 12 333 infants who met the inclusion criteria, 240 (1.9%) experienced treatment failure. The treatment failure rates were 1.6% for children who received short-course intravenous antibiotic treatment and 2.2% for children who received long-course treatment. Treatment courses varied substantially across hospitals and with patient-level characteristics. After multivariate adjustment, including propensity scores, there was no significant association between treatment group and outcomes, with an odds ratio for long versus short treatment of 1.02 (95% confidence interval: 0.77–1.35). Known presence of genitourinary abnormalities, but not age, predicted treatment failure.


Treatment failure for generally healthy young infants hospitalized with UTIs is uncommon and is not associated with the duration of intravenous antibiotic treatment. Treating more infants with short courses of intravenous antibiotic therapy might decrease resource use without affecting readmission rates.

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