Clinical studies of antimicrobial prophylaxis of recurrent urinary infection in women. Long-term, low-dose pipemidic acid for prophylaxis

The prophylactic efficacy of long-term, low-dose antimicrobial treatment in urinary tract infection (UTI) was studied. Fifty-eight female adult patients with a history of at least two recurrent episodes of UTI in the past year were entered into this study, and the prophylactic regimen was not started until the existing UTI had been eradicated. Patients took 250 mg of pipemidic acid (PPA) daily at bedtime after voiding for 6 consecutive months. Incidence of recurrence of UTI in 48 patients with uncomplicated UTI and 10 patients with complicated UTI decreased to 0.15 and 0.29 per year, respectively, during the treatment compared with 3.5 per year before the treatment. At the end of the 6 months of prophylactic treatment, the patients were divided into two groups by the envelope method. Seventeen patients were treated for a further 6 months and 11 patients were followed up without further medication. Prophylactic efficacy of UTI was obtained in both groups, and there was no significant difference in the incidence of recurrence between the two groups. These findings suggest that the 6-month period of prophylaxis might be sufficient. Examination of the periurethral swab showed that E. coli and Klebsiella sp. were decreased during the treatment. This prophylactic treatment produced no resistant strains. Urinary levels of PPA in the morning urine of patients administered 250 mg of PPA at bedtime averaged 513 micrograms/ml. These values were about 2 times higher than those found in the evening urine after administration of the same dose in the morning.