Trimethoprim-rifampin, a new combination agent: efficacy in localized urinary infection and influence on microflora.

Twenty women with recurrent or persistent urinary tract infections were treated with a fixed combination of trimethoprim-rifampin (TMP-RAM). The site of infection was established by the antibody-coated bacteria test. Sixteen women had upper tract infections (antibody-coated bacteria tests positive); eight were cured, three failed, and five relapsed. All four women with lower tract infections (antibody-coated bacteria tests negative) were cured. Three of five patients with structural abnormalities failed. The 12 cures and 5 relapses were associated with organisms susceptible to either TMP (minimal inhibitory concentration, less than or = to 7 micrograms/ml) or RAM (minimal inhibitory concentration, less than or = to 32 micrograms/ml). In contrast, two of the three failures were associated with organisms resistant to both TMP and RAM. In one patient, RAM resistance emerged during treatment. During therapy, urinary strains were eradicated from the periurethral and anal-canal areas in all but 3 fo 16 patients. Adverse reactions, noted in 16 women, included nausea (10), dizziness (6), headaches (2), rash (1), an blurred vision (1). Antimicrobial susceptibility data on 246 isolated from urinary, periurethral, and anal-canal specimens are included. Our findings suggest that TMP-RAM is effective in urinary infections and may prevent the emergence of RAM-resistant strains.