Background: Some authors have assessed the utility of considering various risk factors in predicting bacteremia in young infants with urinary tract infection (UTI) in studies that included only febrile patients. Our aims were to determine whether fever was a predictor for bacteremia and to identify other associated risk factors.
Methods: A retrospective study was conducted that included infants 29 to 90 days of age with UTI attended in the Pediatric Emergency Department from September 2006 through May 2013. UTI was defined as growth of ≥ 50,000 colony forming units/mL of a single pathogen from a catheterized specimen in association with an abnormal urinalysis. Patients without a blood culture were excluded. Univariate testing was used to identify clinical and laboratory factors associated with bacteremia. Receiver operating characteristic curves were constructed for the laboratory markers associated with bacteremia.
Results: We analyzed 350 patients; 77 (22%) were afebrile. Ten had bacteremia (2.9%, 95% confidence interval: 1.6%-5.2%). No other adverse events were identified. No differences were found in bacteremia rates between febrile and afebrile patients (2.9% vs. 2.6%; P = 1.0). Risk factors detected for bacteremia were classified as not well-appearing (25.0% vs. 2.1%; P = 0.003) and a procalcitonin value ≥ 0.7 ng/mL (6.4% vs. 0.5%; P = 0.001). These low-risk criteria yielded a sensitivity of 88.9% for detecting bacteremia with a negative predictive value of 99.5%.
Conclusions: Afebrile young infants with UTI should not be classified a priori as low risk for bacteremia. Well-appearing young infants with UTI and procalcitonin value <0.7 ng/mL were at very low risk for bacteremia; outpatient management with an appropriate follow-up could be considered.