nvasins help to promote bacterial spread within the tissues of the body. Alpha toxin is the most characterized and potent membrane-damaging toxin secreted by S. aureus. It is originally expressed as a monomer that binds to the surface of susceptible cells before becoming oligamerized into a heptomeric ring that causes a pore in the membrane of the attacked cell, which causes the contents of the cell to leak out. Platelets and monocytes are especially susceptible to this toxin. ß-toxin is a sphingomyelinase toxin that damages lipid membranes that are rich in sphingomyelin. It is not often expressed in human isolated strains of the bacteria [8].
A mere 2% of S. aureus isolates express leukocidin, a multicomponent protein that acts to severely damage cell membranes, but 90% of S. aureus strains isolated from severe dermonecrotic lesions are found to express this toxin. This correlation suggests that the toxin is a large component of necrotizing skin infections. Leukocidin forms a hetero-oligameric transmembrane pore made from four LukF and four LukS subunits. This toxin is hemolytic, but not as hemolytic as alpha toxin.
S. aureus also produces a host of proteases, lipases, and DNase, and FAME (fatty acid modifying enzyme). FAME may be important for virulence in abscesses, where it could prolong bacterial survival by modifying anti-bacterial lipids in the cell [8].