Studies on the pathogenesis of staphylococcal infection. IV. The effect of bacterial endotoxin.

Intracutaneous and intravenous injection of pyrogenic, non-lethal doses of bacterial endotoxin were found to increase the infectivity of pathogenic but not non-pathogenic staphylococci in rabbit skin. The increased infectivity of the microorganism was characterized by accelerated multiplication at the site of inoculation and by the production of necrosis and hemorrhage locally. Histologically, the infection of skin in endotoxin-prepared animals was characterized by necrosis, masses of bacteria, but absence of leukocytic infiltration into the area of bacterial growth. The infectivity of staphylococci in skin of endotoxin-prepared rabbits could be controlled by antibody to the alpha hemolysin of the microorganism. The effect of endotoxin upon staphylococcal infection was demonstrable only within 4 hours after injection of the endotoxin. It could not be prevented with chlorpromazine or dibenamine and was closely related to the effect of endotoxin upon leukocytes. It was suggested that the effect of endotoxin upon leukocytes was probably responsible for its influence upon staphylococcal infection. The implications of these findings in the pathogenesis of staphylococcal infection are discussed.