Protective Action of Sulfapyridine in Rabbits Infected with Pneumococci. ∗

Abstract

Most of the studies on the protective action of sulfanilamide and sulfapyridine on streptococcic and pneumococcic infections have been made on white mice. In the work here reported rabbits were used as the experimental animals. Intracutaneous inoculations were made in order to permit the observation of differences in the local lesions occurring in the treated and the control groups.

Rabbits weighing approximately 2 kilos were given 0.3 cc of a 1-100 dilution of an 8-hour culture of a Type II pneumococcus. The strain used had been transferred alternately through mice and veal broth for more than a year.

Intraperitoneal injections of 0.2 cc into mice, in dilutions of 1:10,000,000, kills 50% of the animals.

Sulfapyridine, 2-(sulfanilamide)-pyridine, was administered orally by suspending in 10% acacia and permitting the suspension to trickle down the throat from a large syringe. The treated animals were given 0.5 g one hour before inoculation, 0.5 g 3 hours after inoculation, and 0.5 g every 12 hours thereafter for a total of 5 g.

In addition to the difference in mortality, there was observed a marked difference in the lesions produced in the treated and control animals. Rhoads and Goodner 1 have reported oedema and a spread of the cutaneous lesion by gravity in rabbits inoculated endermally with pneumococci. These results were evident in our control group. The treated animals showed little or no oedema, and probably because of this, showed little or no spread by gravity. That an infection was present in the skin was evidenced by the area of inflammation in the skin of treated animals. The above authors have also stated that in occasional animals they find signs of hemorrhage in the skin. In the lesions of our control series there were extensive hemorrhages, caused either by the virulence of our strain or by the age of the culture.