Prevention of recurrent urinary tract infections in girls.

Eighteen girls between the ages of 3 and 13 years--with a history of at least three culture-documented episodes of bacteriuria in the previous year, but without radiologic evidence of major urinary tract abnormality--were placed on a double-blind, crossover study comparing the effectiveness of nitrofurantoin macrocrystals against a placebo in preventing the recurrence of bacteriuria. Each child was placed on a daily low dose of nitrofurantoin (1.2 to 2.4 mg/kg/day) or an identical-appearing placebo for six months. Each child was then placed on the opposite capsule for a similar period. There were 35 episodes of bacteriuria (4.2 episodes/patient/yr) in the patients taking the placebo, which compared with a rate of 3.8 episodes/patient/yr during the year prior to the study. Only two episodes (0.2 episodes/patient/yr) occurred in the patients taking the drug. The difference in the rate of recurrent bacteriuria between the girls on placebo and on medication is significant at the 0.01 level using the Wilcoxin matched-pairs test. There were no adverse reactions to the drug. Nitrofurantoin macrocrystals in a single daily low dose appear to be a safe, effective method of preventing recurrent bacteriuria in girls at high risk.