Incidence of Breakthrough Urinary Tract Infection in Hospitalized Infants Receiving Antibiotic Prophylaxis.

Urinary tract infections (UTIs) are a source of substantial morbidity in children in the neonatal intensive care unit. The incidence of UTIs that occur in critically ill infants during a course of antibiotic prophylaxis (i.e., breakthrough urinary tract infections [BUTIs]) is not known. We investigated the incidence of BUTI in a cohort of infants hospitalized on prophylactic antibiotics in neonatal intensive care units. Predictors of BUTI were evaluated using multivariable Cox regression. Out of 716 787 infants, 631 (0.09%) were prescribed 821 courses of antibiotic prophylaxis. Among this cohort, 60 infants (9.5%) suffered a total of 65 BUTIs. Of all prophylactic antibiotic courses, 65/821 (7.9%) were complicated by BUTI. Klebsiella, Enterobacter, and Escherichia coli species were the most common causes of BUTI. There was no statistically significant difference ( P = .78) in BUTI incidence among the 4 antibiotics assessed (amoxicillin, cephalexin, nitrofurantoin, or trimethoprim-sulfamethoxazole).