Differentiating roseola infantum with pyuria from urinary tract infection

The aim of this study was to identify factors for differentiating roseola infantum from urinary tract infection (UTI) and to describe a cohort of infants diagnosed with roseola infantum and sterile pyuria.

The medical records of infants diagnosed with roseola infantum or UTI were examined. Multivariate analysis was performed to identify factors associated with UTI. Demographic and clinical variables were compared between infants who had roseola infantum with or without sterile pyuria.

There were 301 infants included: 158 in the roseola group (21, 13.3% with sterile pyuria) and 143 in the UTI group. The relative risk of UTI over roseola infantum: increased with leukocytosis (white blood cell [WBC] count >10,000/mm(3), odds ratio [OR] = 85.62) and pyuria (OR = 18.97); decreased with age (OR = 0.90); increased in boys (OR = 2.48); increased with WBC count 4000-10,000/mm(3) (OR = 4.24); and decreased with duration of fever (OR = 0.84). There was a significantly higher proportion of girls in the roseola pyuria group (81.0%) compared with the no pyuria group (44.5%, P = 0.002). A significantly higher proportion of infants in the roseola pyuria group (76.2%) received antibiotics than infants in the no pyuria group (38.0%, P = 0.002).

Leukocytosis is the strongest predictor of UTI over roseola infantum. Sterile pyuria may occur in infants with roseola infantum.