Combined Immuno and Chemotherapy of Pneumococcus Rat Infections

Abstract

Fleming 1 has shown that type specific antipneumococcus serum increases the antibacterial action of sulfapyridine in vitro against pneumococci. McIntosh and Whitby 2 have shown, moreover, that sulfapyridine does not stimulate phagocytosis or antibody production against pneumococci, but suppresses their growth to a point that biological defense can become effective. Subsequently, we 3 showed that a small dose of broadly acting non-type-specific antipneumococcus serum, of itself only partially effective, becomes highly effective when fortified with a single partially effective dose of sulfapyridine. This enhanced effectiveness was demonstrated in rat infections with pneumococci of 6 different types, and simplification of treatment was attained through use of a single broad antiserum.

Maclean, Rogers, and Fleming 4 have recently shown the importance not alone of passively introduced pneumococcus antibody but also antibody actively incited by pneumococcus vaccine in the combined immuno and chemotherapy of pneumococcus infection in mice and rabbits. These authors have made a strong case for combined use of vaccine and sulfapyridine in treatment of pneumonia. They considered the utilization of 30 types of vaccine.

Inasmuch as we have used pneumococcus vaccine some of which has given broad effects in rabbits, 3 5 it became of interest to test the combined therapeutic effectiveness of the vaccine and sulfapyridine directly in different types of pneumococcus rat infections. This report gives the results of these tests in a comparative way.

The pneumococcus cultures and vaccines used have been described heretofore. 3 5 Vaccines made from certain cultures, namely, DRI, type II, and type V, had been found to incite the broadest antibodies in rabbits, hence vaccines of these separate and combined types were used in the experiments herein described. Since exposure of the vaccine to 37°C for a week appeared to enhance immunizing properties against heterologous type infections, this procedure was adhered to in preparation of these vaccines which always appeared preponderately gram negative.