Parenteral antibiotic treatment duration in young infants with bacteraemic UTI was variable and only minimally explained by measurable patient factors. Relapses were rare and were not associated with treatment duration. Shorter parenteral courses may be appropriate in some infants.

Objectives: To report the prevalence of bacteremia by age in a sample of infants <1 year of age with urinary tract infections (UTIs), to compare characteristics of infants with UTIs with and without bacteremia, and to describe treatment courses and 30-day outcomes in infants with UTIs with and without bacteremia. Methods: We used a retrospective cross-sectional design to determine the prevalence of bacteremia in infants with UTIs at our institution. A double cohort design matching for age and gender was used to compare clinical characteristics and outcomes between infants with bacteremic versus nonbacteremic UTIs. Results: We identified 1379 UTIs, with blood cultures obtained in 52% of cases. The prevalence of bacteremia was 4.1% (95% confidence interval 3.1%–5.3%) for all UTIs and 8% (95% confidence interval 6.1%–10.2%) for UTIs in which blood culture was obtained. Fifty-five infants with bacteremic UTIs were compared with 110 infants with nonbacteremic UTIs. Except for minor differences in the urinalysis and serum band count, there were no significant differences in clinical presentation between the 2 groups. Bacteremic infants received longer parenteral treatment courses than nonbacteremic infants (mean 6.7 vs 2.4 days, P < .001). Treatment courses in the bacteremic group were variable and predicted by age but not severity of illness. No bacteremic infant had recurrent UTI or bacteremia with the same organism within 30 days of discharge. Conclusions: Treatment was variable but outcomes were excellent in infants with bacteremic UTIs.

Although RUS and VCUG abnormalities were common in this cohort, the frequency and severity were similar to previous studies of infants with UTIs in general. Our findings do not support special consideration of bacteremia in imaging decisions for otherwise well-appearing young infants with UTI.