Staphylococcus aureus continues to be a major cause of infection in normal as well as
immunocompromised hosts, and the increasing prevalence of highly virulent community-
acquired methicillin-resistant strains is a public health concern. A highly expressed surface
component of S. aureus, protein A (SpA), contributes to its success as a pathogen by both
activating inflammation and by interfering with immune clearance. SpA is known to bind to
IgG Fc, which impedes phagocytosis. SpA is also a potent activator of tumor necrosis factor α …