The Comparative in Vitro Action of Sulfanilamide, Sulfapyridine and Sulfathiazole in Urine

Abstract

The in vitro action of sulfanilamide, sulfapyridine and sulfathiazole (50mg% and 100mg% conc.) in urine toward Staphylococcus aureus, Strep. jecalis [alpha], Escherichia, Aerobacter, and Proteus was studied. The drugs were dissolved in pooled normal human urine and then filtered through Seitz filters. Broth cultures or saline dilutions of the cultures were used for inoculation. The number of bacteria per cc. of the urine at once and after 24 hrs. of incubation at 37[degree]C was detd. Very slight or no bacteriostasis toward large numbers of the organisms was obtained. Using lighter inoculum all 3 drugs caused a marked reduction or complete sterilization of the organisms tested. At the 50 and 100 mg% levels little difference was found in the in vitro action of sulfanilamide, sulfapyridine and sulfathiazole. When the same drugs were tested in urine that had been acidified, bacteriostasis was more marked than with alkaline urine, probably due to the effect of the acidity rather than to increased efficacy of the drugs. Sulfathiazole excreted in the urine following administration of the drug is more active than the same amt. added to normal, voided urine.