Studies of staphylococcal infections. II. The role of bacteriophage type, antibiotic resistance, coagulase, and other exotoxins in infections in embryonated eggs.

Numerous investigations have attempted to define those factors responsible for the virulence of Staphylococcus aureus.'" Almost all of the enzymes and exotoxins produced by staphylococci have at some time been purported to be responsible for their pathogenicity but none has been clearly demonstrated of paramount importance.'" The relation of coagulase and alpha hemolysin to the pathogenesis of staphylococcal infection has been particularly well studied,'" "" yet correlation between quantitative production of these toxins and clinical virulence of staphylococci has not yet been established.""'21 Animal studies have suggested that coagulase may be important in the pathogenesis of experimental lesions.`82 Such studies have been hampered by the relative resistance of most laboratory animals to staphylococcal infections."' A few strains of staphylococci capable of producing lethal infections in mice after intra-peritoneal injection of relatively small numbers of bacteria have been isolated.`" These mouse-virulent strains are unique in producing only free coagulase but not bound coagulase, or clumping factor, while nearly all clinical isolates of Staphylococcus aureus produce both free and bound coagulase.' This relationship between virulence and production of free but not bound coagulase has not been established in other experimental animals. The present studies were undertaken to further evaluate the relation of free and bound coagulase production to the virulence of staphylococci and the role of coagulase in infections in embryonated eggs. Earlier investigations have established the extreme sensitivity of embryonated eggs to lethal infection