Clinical predictors of positive urine cultures in young children at risk for urinary tract infection.
BACKGROUND
Urinary tract infections (UTIs) are a common source of bacterial infection among young febrile children. The diagnosis of UTI is challenging because the clinical presentation is not specific.


OBJECTIVE
To describe clinical predictors to identify young children needing urine culture for evaluation of UTI.


METHODS
Retrospective cohort study of all children younger than two years of age (719 hospital visits for 545 patients) suspected of having a UTI during a 12-month period. The outcome was UTI, defined as a catheterized urine culture with pure growth of 10⁴ colonies/mL or greater, or suprapubic aspiration culture with 10³ colonies/mL or greater. Candidate predictors included demographic, historical and physical examination variables.


RESULTS
The medical records of 545 children younger than two years of age were reviewed. Forty-six per cent were girls. Mean age was 9.1 months (SD 7 months). Four variables were found to predict UTI: absence of another source of fever on examination (odds ratio [OR]=41.6 [95% CI, 8.8 to 197.4]), foul smelling urine (OR=19.7 [95% CI, 5.7 to 68.2]), white blood cell count greater than 15,000/mm³ (OR=4.3 [95% CI, 2.0 to 9.3]), younger than six months old (OR=3.1 [95% CI, 1.3 to 7.1]). The sensitivity of an abnormal urine analysis was 0.77 (95% CI, 0.66 to 0.88) and the specificity was 0.31 (95% CI, 0.2 to 0.42).


CONCLUSIONS
An incremental increase in risk for UTI is associated with younger age (younger than six months), having a white blood cell count higher than 15,000/mm³, parental report of malodorous or foul smelling urine and the absence of an alternative source of fever. In the present patient population, obtaining a urine culture from children with at least one of these clinical predictors would have resulted in missing one UTI (2%), and 111 negative cultures (20%) would have been avoided.
Couture
Elise
E
Département de pédiatrie, Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke (Québec).
Labbé
Valérie
V
Cyr
Claude
C