Recurrence and follow-up after urinary tract infection under the age of 1 year.

In order to analyze the risk factors for recurrence and the value of routine follow-up by monthly urine cultures in a group of children who had their first episode of urinary tract infection (UTI) under 1 year of age, we performed a retrospective survey of 262 children (134 girls, 128 boys) who were treated for their first UTI while aged under 1 year in the Department of Pediatrics, University of Oulu, during the years 1978-1984. Detailed data on these children concerning their first and recurrent UTIs were collected from hospital records using a formulated data sheet. Causative bacteria and vesicoureteral reflux (VUR) were analyzed as possible risk factors for recurrent UTI. The time of recurrence and the possible symptoms during the recurrent UTI were also investigated. The follow-up period after the first UTI was 3 years; 35% of the boys and 32% of the girls contracted a recurrent UTI during the 3-year follow-up. In 86% of cases, the first UTI recurrence occurred within 6 months of the primary UTI. Recurrent UTIs were detected significantly earlier with routine monthly follow-up compared with those seeking treatment because of symptoms (log rank test P < 0.01). There was a significant difference in the number of recurrences of UTI according to the grade of VUR (P = 0.006). Recurrence-free survival was shorter and recurrent UTIs occurred more often in the children with grade 3-5 VUR than in those with grade 0-2 VUR (log rank test P = 0.0005). Children without VUR and children with grade 1-2 VUR did not differ in the recurrence rate, and thus grade 1-2 VUR did not increase the risk for recurrent UTI. Monthly routine urine cultures are efficient in detecting recurrent UTI infections in children. Since grade 3-5 VUR is a risk factor both for increased recurrence rate of UTI and for possible subsequent renal damage, these children should be followed with monthly urine cultures for UTI recurrences if not on preventive medication. Since the vast majority of UTI recurrences occur within 6 months of the first UTI, routine follow-up for 6 months seems to be sufficient after symptomatic UTI in children with grade 3-5 VUR.