Urinary Predictors of Bacteremia in Febrile Infants with Urinary Tract Infection

Background: Predicting the risk of bacteremia in febrile infants with urinary tract infection (UTI) remains a diagnostic challenge. Prior studies have focused on the utility of blood biomarkers in predicting the risk of bacteremia in febrile infants, the role of urinary components in predicting bacteremia remain unexplored. This study aims to evaluate the utility of components of urinalysis (UA) in predicting bacteremia in febrile infants < 3 and 3–24 months with UTI.

Methods: We reviewed records of 2000 febrile children 0–24 months with UTI, seen over a 6-year-period in the pediatric emergency department. We defined UTI as positive urine culture, based on the 2016 AAP thresholds. Descriptive, chi-square, and logistic regression analyses were performed as appropriate, including test probabilities (sensitivity [Sn], specificity [Sp], and negative predictive value [NPV]) to evaluate the bacteremia predictive probabilities of components of UA using SAS-9.4®.

Results: Of 813 febrile infants with UTI who had blood cultures, 82 (10.1%) had bacteremia. There was no statistically significant difference between compared groups in terms of sex, ethnicity, or urine collection method. Infants < 3 months had significantly higher prevalence of bacteremia compared to infants 3–24 months (14.3% vs. 4.3%, p < 0.0001). Urinary predictors of bacteremia in infants < 3 months include bacteriuria-(pOR:2.3, p = 0.010, Sn-80.0%, NPV-91.8%, Sp-36.8%), pyuria-(pOR-6.7, p = 0.031, Sn-98.4%, NPV-97.4%, Sp-10.0%), and growth of E. coli in urine culture- (pOR-9.8, p = 0.0006, Sn-98.5%, NPV-98.1%, Sp-12.9%). There were no UA predictors of bacteremia among infants 3–24 months.

Conclusion: Components of UA may be useful in predicting bacteremia in febrile infants < 3 months with UTI. Among infants < 3 months with UTI, potential predictors of bacteremia were bacteriuria, pyuria, and growth of E. coli on urine culture. Urinary components did not predict bacteremia in infants 3–24-months.