Active Immunity to Pneumococci in Rabbits Protected by Sulfapyridine.

Abstract

The results of experiments on the protection of rabbits, infected with pneumococci, by oral administration of sulfapyridine have been reported previous1y.l The purpose of this communication is to present data obtained in the study of the immunity in animals that had recovered from the infection produced under such circumstances.Rabbits weighing approximately 2 kilos were inoculated intracutaneously with 0.3 cc of a l/lOO dilution of an %hour culture of a pneumococcus type 11. The inoculum contained an average of 300,000 organisms as determined by plate-count. The virulence of the organism is such that an average of 1.5 organisms are necessary to cause an infection in 66% of a statistically sized group of mice weighing 20 g. This we have taken to be our minimal lethal dose. Its virulence for rabbits is such that 0.3 cc of a 1/1000 dilution of the original culture, containing 30,000 organisms, will kill all of the rabbits inoculated.The drug-treated animals were given sulfapyridine orally in a 10% acacia suspension. Each animal received a total of 5 g of the drug, 0.5 g 1 hour before infection, 0.5 g 3 hours after the initial dose, and 0.5 g every 12 hours thereafter until the full dosage was administered.Daily record was made of the temperature, and the size and nature of the skin-lesion. Rabbits recovering from the primary infection were reinoculated intracutaneously in the same general areas as previously, but not at the site of the original lesion if a scar had persisted. Only normal areas of the skin were used for reinoculation.Twelve rabbits reinoculated intracutaneously with 0.3 cc of the whole %hour culture of the homologous type I1 pneumococcus 30 days after the original infection, showed no rise in temperature, and no local reaction around the point of inoculation. Five rabbits reinoculated 62 days after the original infection, and 5 after 83 days, showed no reaction. Of three rabbits Type-specific Immunity.

Immunological Studies of Pneumococcal Pneumonia in Patients Treated With Penicillin 1

“…The early development of circulating antibodies and active 'resistance was not influenced by the administration of sulfonamide (11)(12)(13).…”

“…Twenty-nine patients received initial penicillin doses of from 20,000 to 50,000 units intramuscularly; 12 patients were given 100,000 units, and three patients 300,000 units. Subsequent dosage in 33 cases ranged from 20,000 to 50,000 units every two to three hours.…”

“…of pneumococcal infections in both man (1)(2)(3)(4)(5)(6)(7)(8) and animals (9)(10)(11)(12)(13) have shown that the development of specific antibodies is not affected by early therapy with sulfonamide drugs. In contrast, early penicillin therapy of rabbits and mice (14) and of rats (15) infected with pneumococci has been observed to suppress or decrease the antibody response of these animals.…”

“…of pneumococcal infections in both man (1-8) and animals (9)(10)(11)(12)(13) have shown that the development of specific antibodies is not affected by early therapy with sulfonamide drugs. In contrast, early penicillin therapy of rabbits and mice (14) and of rats (15) Twenty-nine patients received initial penicillin doses of from 20,000 to 50,000 units intramuscularly; 12 patients were given 100,000 units, and three patients 300,000 units.…”

The Effect of Sulfapyridine Upon the Development of Immunity to Pneumococcus in Rabbits

“…An apparent correlation was observed not only between the survival rate and the relative antigenicity of the respective types of pneumococci, but also between the differences in the time required for the development of antibodies and the length of time during which it was necessary to continue sulfapyridine treatment. Larson, Bieter, and Levine (7,8) demonstrated that rabbits which recovered from intradermal infection with Pneumococcus Type II following treatment with sulfapyridine were highly resistant to reinfection with the homologous type of organism 30 or more days later.…”