Pediatric patients between the ages of 2 and 24 months who present with fever without a known source present a particular challenge because of the exceedingly nonspecific clinical presentation.¹ Asymptomatic bacteriuria and true urinary tract infections (UTIs) are often difficult to distinguish, which has led to overtesting, overdiagnosis, and overtreatment in otherwise healthy children.² In this column, I’d like to dispel some common myths and misperceptions about pediatric UTI that will better arm you to tackle this challenging problem. I’ll outline a standardized approach to pediatric UTI so that you know who to screen, how to screen, and what to do with the screen results, thereby reducing the risk of harm caused by excessive antibiotic use.

While observational data reveal that 7 percent of children 2 to 24 months of age presenting to the emergency department with isolated fever without an obvious source have a UTI, the prevalence of urosepsis in otherwise healthy, immunocompetent children has been estimated to be only 1 in 25,000.^3,4

The most important clinical predictors of UTI in the 2– to 24-month age group include temperature >40°C, fever >24 hours, suprapubic tenderness, jaundice, and, in males, lack of circumcision.¹ While “history of prior UTI” was shown to be predictive of UTI, it is important to recognize that prior false positives can be misleading, as earlier diagnoses may have been made speculatively without cultures or the culture results themselves may have been false positives. Placing patients in a high-risk category for UTI when they present with fever without a source based on a “history of UTI” is therefore a common pitfall that leads to overdiagnosis and overtreatment.

Negative predictors of pediatric UTI include an alternate obvious source of infection. A question that frequently arises is, does a febrile bronchiolitis presentation rule out UTI? A recent meta-analysis found the incidence of UTI in patients with bronchiolitis to be 0.8 percent, far lower than in previous studies suggesting testing for UTI in febrile bronchiolitis patients.⁵ It appears that most positive urine cultures in infants >2 months of age with bronchiolitis result from contamination or asymptomatic bacteriuria.

Urine specimen interpretation can lead to misdiagnosis. No single element of a urinalysis is sensitive enough to rule a UTI in or out; while nitrites are highly specific but not sensitive, leukocyte esterase is sensitive but not very specific.¹

UTI Calculator

A risk-stratification decision tool (https://uticalc.pitt.edu) has been developed to help physicians decide which infants 2–24 months of age require testing for UTI and which of those patients require treatment with antibiotics while cultures are pending.6 It involves a two-step process. In the first step, five questions are asked: