The first urinary tract infection in the female infant. Prevalence, recurrence, and prognosis: a 10-year study in private practice.

Eight hundred healthy female infants presenting for routine care were systematically screened for bacteriuria from early infancy to 2 years of age. The initial urinary tract infection was established in 29 infants, 3.6% of the series, at a median age of 9 months. Continued systematic screening of 25 of these 29 infants with bacteriuria to 6 years of age revealed recurrent infection in nine of them and the development of pyelonephritis in three. Recurrent episodes of infection occurred at close intervals of 2 weeks to 4 months in these nine infants and were clustered within an 18-month period. There were no recurrences after 3 years of age. Characteristically, both the initial and recurrent infections were asymptomatic. Lower urinary tract signs of infection, however, were evident to the "instructed parent," i.e., one instructed in the use of the urinary diary, a written log of the parents' observations of the infant's voiding habits. Pyelonephritis developed early in the children with recurrent infections; it was clinically inapparent and developed in infants with (initially) normal urinary tracts.