Treatment of uncomplicated urinary tract infections with trimethoprim versus sulfisoxazole, with special reference to antibody-coated bacteria and fecal flora

A total of 331 college-age women with urinary tract infections were studied. These women were assigned randomly to the following groups: 50 patients treated with 400 mg of trimethoprim (TMP) per day for 14 days (designated the TMP400/14d group); 50 treated with 2.0 g of sulfisoxazole (SZ) per day for 14 days (SZ/14d group); 120 treated with 200 mg of TMP per day for 10 days (TMP200/10d group); and 111 treated with 2.0 g of SZ per day for 10 days (SZ/10d group). By the last day of therapy, clinical and bacteriological cure rates were 100% in the TMP400/14d, SZ/14d, and TMP200/10d groups and 97.1% in SZ/10d group. At 1 week after therapy ended, the initial urinary pathogens remained eradicated in 100% of the TMP400/14d group, 98.2% of the TMP200/10d group, 95.6% of the SZ/14d group, and 98.0% of the SZ/10d group at 4 weeks after therapy ended, the clinical cure rates were 92.0% in the TMP400/14d group, 92.0% in the SZ/14d group, 89.0% in the TMP200/10d group, and 90.0% in the SZ/10d group. At 4 and 24 weeks after therapy ended, the recurrence rates in the four treatment groups did not differ significantly. The antibody-coated bacteria test localized 39.5% of the infections to kidneys and 56.8% of the infections to bladders. Neither symptoms nor responses to therapy were correlated with the antibody-coated bacteria test results. Both TMP at a dose of 200 mg/day and SZ were tolerated well. TMP at a dose of 400 mg/day was associated with a skin rash in 24% of the patients receiving this therapy. TMP suppressed fecal Escherichia coli. SZ increased the number of sulfa-resistant fecal isolates; however, this phenomenon did not affect the rate of sulfa-resistant recurrences.