Treatment of cystitis in women with a single dose of trimethoprim-sulfamethoxazole.

The efficacy of a single dose (four tablets) and of 10-day courses of trimethoprim-sulfamethoxazole (TMP-SMZ) was studied in 77 women with symptomatic cystitis and negative tests for antibody-coated bacteria. Cure rates after six weeks were 76% for single-dose therapy and 87% for 10 days of treatment. For Escherichia coli infections, cure rates after six weeks were 80% and 86%, respectively. However, 10-day treatment eliminated enteric bacilli from urethral and vaginal sites more often than did single-dose therapy. Two weeks after completion of treatment, perineal colonization was observed more often in the women who developed recurrent infections than in those who did not (P = 0.01). During these two weeks, recurrent infections were found somewhat more often in the women who had received single-dose therapy than in those who had undergone 10-day treatment (5 of 38 vs. 2 of 39; P = 0.07). With conventional courses of antibiotics, retreatment of all recurrent infections was less successful in women previously given single-dose therapy. Recurrent infections were also more frequent in women infected with bacteria other than E. coli. Both drug regimens were well tolerated. However, serious adverse reactions were fewer in patients treated with a single dose (8.5%) than in patients treated for 10 days (15%). Single-dose therapy with TMP-SMZ appears as effective as 10-day therapy in acute uncomplicated cystitis caused by E. coli.