Abstract
Cell walls of an 80/81 strain of Staphylococcus aureus are agglutinated by antisera prepared against intact organisms of this species. The reaction appears to be group specific. A teichoic acid consisting of ribitol -phosphate and glucosamine was isolated from the cell walls of this strain. The material reacts with S. aureus antisera in the precipitating and hemagglutinating systems. Hapten inhibition studies indicated that the antigenic determinant of this compound is N-acetylglucosamine in [beta] glycosidic linkage. The antigen sometimes reacted with normal human sera at low serum dilutions. Serum from one patient with staphylococcal disease was highly reactive.