Effect of Temperature on Bacteriostatic Action of Sulfanilamide upon Members of the Enterococcus Group

Abstract

Until recently, the members of the enterococcus group were considered to be rather resistant to the bacteriostatic and bactericidal action of sulfanilamide, both in vivo and vitro. Thus, Helmholz and Osterberg 1 found that sulfanilamide when given by mouth produces a urine strongly bactericidal for microorganisms usually found in urinary infections with the exception of the Streptococcus fecalis. Bliss and Long 2 reported that hemolytic enterococci (Lancefield group D) were not affected by sulfanilamide in a concentration of 1:10,000 in beef infusion, neopeptone broth, even when the broths were inoculated with relatively small numbers of microorganisms. In contradistinction to fibrinolytic hemolytic streptococci, several strains of hemolytic enterococci were not or only slightly inhibited in 1% dextrose broth containing 0.8% sulfanilamide, when one loopful of a 16 to 18 hours broth culture was used for inoculation (Neter 3 , 4 ). Long and Bliss 5 reported that hemolytic enterococci, Lancefield Group D, are resistant to the bacteriostatic action of sulfanilamide in concentrations up to 800 mg %; above this concentration a slight retarding of growth was noted with a few strains.

Recent experiments, however, revealed that under certain conditions it may be possible to demonstrate a definite bacteriostatic action of sulfanilamide upon members of the enterococcus group. Bliss and Long 6 found that the growth of enterococci may be definitely delayed, provided that high concentrations of sulfanilamide and small inocula are used. A marked bacteriostatic action of sulfanilamide in concentrations from 800 mg % to 1000 mg % upon hemolytic enterococci could be demonstrated, 7 employing as culture medium, 1% maltose phenol red broth containing from 6.5% to 7% sodium chloride. In this broth the growth of hemolytic enterococci is markedly delayed.