Broadly protective vaccine for Staphylococcus aureus based on an in vivo-expressed antigen

Vaccines based on preferential expression of bacterial antigens during huma n infection have not been described. Staphylococcus aureus synthesized poly -N-succinyl beta-1-6 glucosamine (PNSG) as a surface polysaccharide during human and animal infection, but few strains expressed PNSC in vitro. All S. aureus strains examined carried genes for PNSG synthesis. Immunization pro tected mice against kidney infections and death from strains that produced little PNSG in vitro. Nonimmune infected animals made antibody to PNSG, but serial in vitro cultures of kidney isolates yielded mostly cells that did not produce PNSC. PNSG is a candidate for use in a vaccine to protect again st S. aureus infection.