Comparative trial of trimethoprim and co-trimoxazole in recurrent urinary infections.

Eighty-nine patients with a history of recurrent urinary infection who required immediate treatment for significant bacteriuria were treated with either trimethoprim (300 mg at night) or with the standard course of co-trimoxazole (two tablets 12-hourly) for seven days. Cure rates one week after the end of treatment were 74.4% and 80.4%, respectively. During the following month the relapse rate was lower in the group given trimethoprim than among those who had received co-trimoxazole. Consequently, the cure rates six weeks after the start of treatment were 71.4% in the trimethoprim group and 58.5% in the co-trimoxazole group. These results suggest that in this type of patient, it may be possible to reduce the incidence of bacteriological relapse by giving antibiotics in larger doses and at less frequent intervals than are at present generally recommended.