PROS Pearls:

* Practitioners obtained a urinalysis or urine culture for only 58% of the febrile infants less than three months of age seen during a recent national pediatric study. This finding is at odds with many published recommendations that suggest urine testing for all febrile infants in this age group. Interestingly, of those infants not initially tested or treated with an antibiotic, only two subsequently were diagnosed as having a urinary tract infection (UTI) and both of these infants did well. The finding suggests that with close follow-up, short-term adverse events from selective urine testing may be uncommon.

* The infant characteristics that most strongly predicted urine testing included: 1) younger age; 2) higher fever; 3) initial ill appearance; and 4) an absence of findings suggesting an alternative source for the fever such as otitis media, upper respiratory tract symptoms, or illness of other family members.

* Several factors were predictive of a UTI in the study, including: 1) uncircumcised boys; 2) female sex; 3) higher fever; 4) lack of ill family members; 5) fever duration of 24 hours or longer; 6) non-Hispanic ethnicity; and 7) lack of respiratory distress.

* Of particular interest are variables that were predictive of a UTI but not of urine testing. The strongest of these included: 1) female sex; and 2) lack of circumcision in males. Compared with circumcised boys, the odds of a UTI were 5.4 times higher in girls, and 11.6 times higher in uncircumcised boys. Additionally, infants with fevers lasting 24 hours or longer had 80% higher odds of a UTI, but were no more likely to have had urine testing.

* The authors note that the results suggest that a selective approach to urine testing is likely to be safe in the hands of experienced practitioners who closely follow up their patients. However, several factors, including female sex, lack of circumcision in males, and a longer duration of fever should be more heavily weighted in deciding which such infants should have urine testing.