Which young infants are most at risk of UTI?

A newly published study has identified variables that are associated with urinary tract infection (UTI) in febrile infants younger than 60 days. The investigation was of more than 1,000 infants who had a temperature of 38 °C or higher who were seen at eight pediatric emergency departments during the respiratory syncytial virus (RSV) season. Investigators analyzed clinical variables believed to be associated with UTI, such as gender, circumcision status, height of fever, white race, and ill appearance. Standard laboratory screening was with microscopic urinalysis or urine dipstick testing. The study group's mean age was 35.5 days and mean temperature, 38.6 °C.

Overall, 9% of infants were found to have a UTI, most often associated with Escherichia coli, which grew in 80% of cultures. Being uncircumcised and having a temperature higher than 39 °C were each a risk factor for UTI. Among 68 male infants who had both of these findings, 23 (34%) were given a diagnosis of UTI. Uncircumcised male infants were at particularly high risk. White race and ill appearance were not found to be significantly associated with the risk of UTI in these young infants (Zorc JJ et al: Pediatrics 2005;116:644).

Commentary Nearly 5% of RSV-positive infants in this study had a UTI. Although 9% of febrile infants studied had UTI, 21.3% of uncircumcised males had this diagnosis! The odds of a febrile, uncircumcised male having a UTI were 10 times greater than were the odds for a circumcised male. Dr. Zorc and his group offer a clear reminder to consider UTI in a febrile infant, even if he, or she, has another source of fever and especially if he is an uncircumcised male.