Comparison of trimethoprim alone with trimethoprim sulphamethoxazole in the treatment of respiratory and urinary infections with particular reference to selection of trimethoprim resistance

Abstract

279 patients were treated with 100 mg trimethoprim or 100 mg trimethoprim combined with 500 mg sulphamethoxazole (co-trimoxazole) twice daily for 5 days in a prospective randomised double-blind trial. In chest infections in patients in general practice and in an acute geriatric assessment unit, the efficacy of each regimen was similar, but there were more side-effects with co-trimoxazole than with trimethoprim alone. In urinary-tract infections the two regimens also produced similar cure rates. Treatment with trimethoprim rarely selected resistant pathogens in the sputum or resistant Enterobacteriacae in the intestine, although the incidence of resistant coagulase-negative staphylococci on the skin increased with both regimens. Most chest and urinary infections hitherto treated with co-trimoxazole should be treated with trimethoprim alone.