Cutaneous and systemic infections of rabbits by Group A streptococci bring about a state of preparation for, respectively, the local and generalized Shwartzman reactions, produced by intravenous injection of meningococcal or S. marcescens toxin.

With maximal systemic streptococcal infections, the lesions of the generalized Shwartzman reaction do not differ from those caused by two successive intravenous injections of Gram-negative bacterial toxins. The characteristic lesions of the reaction are bilateral cortical necrosis of the kidneys, hemorrhagic necrosis in the lungs, liver, and spleen, and myofiber necrosis in the myocardium.

Under optimal conditions involving the dosages of streptococci and toxin, and the time interval between the injections, a new lesion consisting of necrosis and the accumulation of fibrinoid material in the walls of the coronary arteries occurred in approximately 50 per cent of animals within 48 hours after the injection of meningococcal toxin.

Fibrinoid necrosis was not observed in the arteries of tissues other than the heart. It did not occur in control rabbits injected with streptococci alone or toxin alone, nor in animals with the generalized Shwartzman reaction produced by two intravenous injections of toxin.

Streptococcal bacteriemia was present at the time of death in one-third of the animals with fibrinoid necrosis. In one animal, a group of bodies resembling cocci in chains was seen within the wall of a coronary artery with fibrinoid necrosis.

A series of photomicrographs to illustrate the pathological changes in the hearts and kidneys of streptococcus-infected rabbits subjected to the Shwartzman reaction is presented.

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