The length of antimicrobial therapy in upper vs. lower urinary tract infection of childhood.

235 infants and children were randomized to a 10-day and 42-day treatment group and followed-up for 12 months after their first urinary tract infection. The anatomical level of each symptomatic infection was determined using simple laboratory criteria. The two regimens prescribed were equally effective in eradicating the infection, but after the discontinuation of the 10-day treatment with sulfafurazole, 17 (23%) of 73 patients with their upper urinary tract infection experienced a recurrence within one month, as compared to only one (1) of 76 subjects in the 42-day therapy group. After the phase of early recurrence, there was no difference in recurrence rate between these groups. The early recurrences were associated with the patient's early age and a short duration of symptoms before therapy. The recurrence rate of first lower UTI after 10-day therapy was significantly lower than that after 42-day treatment. The duration of antimicrobial therapy for childhood urinary tract infection should be adjusted according to the patient's age and the anatomical level of the infection. 10-day treatment may not be sufficient to prevent early recurrence of pyelonephritic infections in infants under 6 months of age.