SULFATHIAZOLE
In former experiments I showed the great variations of the effect of sulfathiazole on twenty-one strains of Escherichia coli. Twenty more strains were added to this series, and the bactericidal action of sulfathiazole on these forty-one strains was tested. The results indicated a low resistance of most strains of Esch. coli to sulfathiazole. At a concentration of 2 mg. of sulfathiazole per hundred cubic centimeters of urine all but four strains were killed off in seventy-two hours (table 1). When the concentration of sulfathiazole was increased to 200 mg. per hundred cubic centimeters three of the four resistant strains were killed off at various higher levels. At the highest level, 200 mg. per hundred cubic centimeters, strain 22 still grew actively when it was inoculated in numbers of less than 100 bacilli per 0.5 cc. of urine.In view of the great range of bactericidal effect, from a definite