How does protein A contribute to the virulence of staph aureus?

IgG antibodies have an Fc portion and a Fab portion (attaches to the antigen). The Fc portion is important in the phagocytosis mediated by antibody opsonization. However, if the protein A is attached to the Fc portion, it will replace the phagocyte and help the Staphylococcus Aureus avoid phagocytosis and its destruction by phagocytic cells.