In vitro and In vivo Effect of Sulfanilamide on Brucella abortus and Brucella suis.

Abstract

In vitro Experiments. Various concentrations of para-amino-benzene sulfonamide∗ were added to dextrose broth, veal-infusion broth, and 10% serum-veal-infusion broth. The effect of the chemical on the growth-rates of Br. abortus and Br. suis was relatively the same regardless of the medium used.

The strains used had been under artificial cultivation for over 2 years but were still pathogenic for guinea pigs. The cultures grew quite well on veal-infusion agar and in the various liquid media mentioned above after incubation for 48 hours at 37°C under ordinary atmospheric conditions.

One-tenth cubic centimeter of a 1:100 dilution of a 48-hour broth culture was seeded into flasks containing 100 cc of broth; sterile 1% solution of p-aminobenzene sulfonamide was added to obtain concentrations of 1:1000, 1:10,000, 1:100,000, and 1:1,000,000. Control cultures did not contain any sulfanilamide.

Plate counts were made before the sulfanilamide was added, 10 minutes after its addition and after 24, 48, and 72 hours'inctbation at 37°C. The initial counts were between 1000 and 3000 organisms per cc. Within 10 minutes after the sulfanilamide was added a marked reduction in the number of viable cells was found in the 1:1,000, 1:10,000, and 1:100,000 dilutions. All the organisms were destroyed during this short period in the 1:1000 dilution, for no colonies appeared on plates subsequently made from both the Br. abortus and Br. suis cultures in this dilution. Most of the organisms were destroyed in the 1:10,000 dilution after 10 minutes'exposure and those remaining were either killed or inhibited by the drug after further incubation. After 72 hours the counts were less than 10 organisms per cc.

In the 1:100,000 dilution the bactericidal effect was less marked but there was a definite bacteriostatic effect throughout the incubationary period. The count after 72 hours was 35,000 per cc for Br. abortus. With the Br. suis strain there were 500 cc after 24 hours and none after 72 hours.