Protein A (3, 8) and the clumping factor (bound coagulase; 1) of Staphylococcus aureus share common characteristics, yet, to our knowledge, they have not been compared to determine possible identity. Both are protein, antigenic, cell surface components of S. aureus but not of S. epidermidis, and both are released into the culture medium as growth develops. Protein A is a common agglutinogen of ...

Of the methods now available for the detection of coagulase positive staphylococei, none is designed to show both clumping factor and free coagulase activity in a single system. The observations reported here are by-products of a search for variant strains of staphylococci with particular reference to strain differences in the cell surface component known as clumping factor or bound coagulase. ...