Staphylococcus toxins and biologically active enzymes
track 4, pathogens
Surface proteins clumping factor and firbrinonectin binding proteins
Clumping factor binds fibrinogen. Fibrinonectin binding proteins bind fibrinonectin. These playe key role in early infection
Protein A binds the Fc portion of IgG, leaving the Ag binding site turned around, protein A contributes to the virulence as an antiphagocytic factor.
Most important determinant of S. aureus versus other staphylococci. Coagulase activates prothrombin without usual proteolytic cleavages to form a fibrin clot.
Alpha toxin inserts into host cell membranes to form pores. It lyses the membranes of host cels. Secreted by most S aureus strains, but not by coagulase negative cocci
Exfoliatin splits intraepidermal junctions.
SAgs are secreted proteins that stimulate systemic effect after absorption from GI track or ingestion. These bind MHC II without processing and cause massive cytokine release.