The Relationship between Temperature and the Streptococcidal Activity of Sulfanilamide and Sulfapyridine in Vitro

Abstract

The minimal bactericidal concs. of sulfanilamide and of sulfapyridine for each of 6 different inoculum sizes of B-hemolytic streptococcus strain C 203 in PD broth were detd. at various temps. between 30 and 39[degree] C. Incubation of drug-bacteria mixtures was maintained for 48 hrs. in water baths with thermoregulator control to 0.005[degree]. Simultaneous titration of drug and culture, each against the other, with sterilization as the end-point for measuring drug activity, was carried out in a total of 312 detns. About 100 times as much sulfanilamide was required to sterilize at 37[degree] as at 39[degree]. Drug concs. of 10 mg.%, or less, were active only at temps. above 37[degree]. Accurate temp. control appears to be an essential part of any reliable method for measuring the activity of these drugs in vitro.