Studies on a Possible Correlation Between Experimental and Clinical Data Concerning the Response of Infection to Serum *

While studyihg the localization of Streptococcus viridans at sites of local antigen-antibody reactions in rabbits sensitized to horse serum, Weisberger (Proc. Soc. Exper. Biol. & Med., 1932, 29, 445) observed that there was a difference in the rate of disappearance of these organisms from the blood stream of normal and of sensitive animals. In the case of the sensitive animals, the bacteremia was definitely and consistently prolonged beyond that which occurred in the normal animals. In the present investigation the effect of the hypersensitive state on experimental Streptococcus hemolyticus bacteremia was studied in rabbits. The organism used was a hemolytic streptococcus which had been isolated from a case of scarlet fever (strain 273). Rabbits were sensitized by repeated injections of normal horse serum. The volume of the bacterial suspension injected was kept constant at 1 cc. A measured quantity of organisms, as determined by the pour-plate method, was inoculated into the ear vein. Blood cultures were taken from the internal jugular vein 15 and 30 minutes, and 1, 2, 3, 6, 9, 12 and 24 hours after the injection, and then every 24 hours until the blood became sterile. Both broth and blood-agar plate cultures were made and the number of colonies was counted for each period from the plate. Three groups of experimental animals were used. Group I included 8 animals, 4 of which were normal controls and received injections of organisms only, and 4 were sensitized animals which were shocked with normal horse serum at the time of bacterial injection. A normal and a sensitized animal were