Twenty-eight-day courses of antibiotics for urinary tract infection

A prospective double-blind study was performed in which 30 adult patients with recurrent urinary tract infections due to Escherichia coli, and Proteus mirabilis organisms were treated by twenty-eight-day courses of either ampicillin, 500 mg. four times a day, or trimethoprim-sulphamethoxazole, 2 tablets twice a day. In terms of freedom from infection fifty-six days after the cessation of treatment in both complicated and uncomplicated infections, trimethoprim-sulphamethoxazole yielded results superior to those of ampicillin. In comparing the results of this study with those of a similar study in which the same agents were given for ten-day courses it appears that only in the complicated infection is there an advantage in giving a prolonged course of trimethoprim-sulphamethoxazole. This study did not generate any evidence to support the extension of ampicillin therapy for urinary tract infection beyond ten days.