Febrile infants with urinary tract infections at very low risk for adverse events and bacteremia

BACKGROUND: There is limited evidence from which to derive guidelines for the management of febrile infants aged 29 to 60 days with urinary tract infections (UTIs). Most such infants are hospitalized for ≥48 hours. Our objective was to derive clinical prediction models to identify febrile infants with UTIs at very low risk of adverse events and bacteremia in a large sample of patients. METHODS: This study was a 20-center retrospective review of infants aged 29 to 60 days with temperatures of ≥38°C and culture-proven UTIs. We defined UTI by growth of ≥50 000 colony-forming units (CFU)/mL of a single pathogen or ≥10 000 CFU/mL in association with positive urinalyses. We defined adverse events as death, shock, bacterial meningitis, ICU admission need for ventilator support, or other substantial complications. We performed binary recursive partitioning analyses to derive prediction models. RESULTS: We analyzed 1895 patients. Adverse events occurred in 51 of 1842 (2.8% [95% confidence interval (CI): 2.1%-3.6%)] and bacteremia in 123 of 1877 (6.5% [95% CI: 5.5%-7.7%]). Patients were at very low risk for adverse events if not clinically ill on emergency department (ED) examination and did not have a high-risk past medical history (prediction model sensitivity: 98.0% [95% CI: 88.2%-99.9%]). Patients were at lower risk for bacteremia if they were not clinically ill on ED examination, did not have a high-risk past medical history, had a peripheral band count of <1250 cells per μL, and had a peripheral absolute neutrophil count of ≥1500 cells per μL (sensitivity 77.2% [95% CI: 68.6%-84.1%]). CONCLUSION: Brief hospitalization or outpatient management with close follow-up may be considered for infants with UTIs at very low risk of adverse events.