Single dose trimethoprim for urinary tract infection.

A randomised clinical trial of single dose trimethoprim against a seven day course of co-trimoxazole (trimethoprim/sulphamethoxazole) for the treatment of uncomplicated urinary tract infection was carried out in 106 children aged between 2 and 16 years. Of the 50 children with confirmed urinary tract infections who were followed up 48 hours after treatment with a single dose of trimethoprim all were free of infection, whereas two of the 56 who received the course of co-trimoxazole (4%) had persisting infections. At follow up after 10 days, however, significantly more of the group treated with trimethoprim had evidence of recurrent urinary tract infection compared with those who had received co-trimoxazole (10 of 44, 23%, compared with one of 46, 2%). Of the recurrences in the trimethoprim group, six were asymptomatic. We conclude that single dose trimethoprim is effective in clearing the urine of bacteria, but the risk of asymptomatic bacteriuria soon after treatment is high.