Potential for vaccination against infections caused by Staphylococcus aureus.

Surface polysaccharides and proteins from S. aureus which could serve as components of a future subunit vaccine against staphylococcal disease in man and animals have recently been characterized. The majority of bovine mastitis and human clinical isolates of S. aureus produce a thin polysaccharide capsule which probably impairs phagocytosis. Protective immunity to S. aureus infections in laboratory animals has been induced by immunization with polysaccharide, and immune serum promotes phagocytosis of bacteria in vitro. S. aureus expresses several surface-exposed proteins that bind host plasma proteins to the bacterial cell or promote adherence of bacteria to host cells or to tissues. These activities may help bacteria avoid host defences and stimulate adherence and colonization to form foci of infection. In this article the properties of S. aureus surface polysaccharides and proteins are reviewed. Their contribution to virulence and the possibility that they could be used as components of new vaccine to combat mastitis in ruminants and nosocomial infections is discussed.