Acute infection of mice with Smith strain of Staphylococcus aureus.

Two serologically distinct variants found in a unique strain of staphylococcus produce coagulase and are phagocytized, but only one is virulent to mice. Only virulent cocci grow rapidly within leukocytes. Leukocyte destruction by the virulent strain and release of many phagocytized cocci precedes mouse death. The leukocidic agent may be delta-hemolysin.