Parenteral Antibiotic Therapy Duration in Young Infants With Bacteremic Urinary Tract Infections.

Objectives: To determine the association between parenteral antibiotic duration and outcomes in infants ≤60 days old with bacteremic urinary tract infection (UTI).

Methods: This multicenter retrospective cohort study included infants ≤60 days old who had concomitant growth of a pathogen in blood and urine cultures at 11 children's hospitals between 2011 and 2016. Short-course parenteral antibiotic duration was defined as ≤7 days, and long-course parenteral antibiotic duration was defined as >7 days. Propensity scores, calculated using patient characteristics, were used to determine the likelihood of receiving long-course parenteral antibiotics. We conducted inverse probability weighting to achieve covariate balance and applied marginal structural models to the weighted population to examine the association between parenteral antibiotic duration and outcomes (30-day UTI recurrence, 30-day all-cause reutilization, and length of stay).

Results: Among 115 infants with bacteremic UTI, 58 (50%) infants received short-course parenteral antibiotics. Infants who received long-course parenteral antibiotics were more likely to be ill appearing and have growth of a non- organism. There was no difference in adjusted 30-day UTI recurrence between the long- and short-course groups (adjusted risk difference: 3%; 95% confidence interval: -5.8 to 12.7) or 30-day all-cause reutilization (risk difference: 3%; 95% confidence interval: -14.5 to 20.6).

Conclusions: Young infants with bacteremic UTI who received ≤7 days of parenteral antibiotics did not have more frequent recurrent UTIs or hospital reutilization compared with infants who received long-course therapy. Short-course parenteral therapy with early conversion to oral antibiotics may be considered in this population.