Occurrence of protein A in Staphylococcus aureus and closely related Staphylococcus species

Abstract
All but 1 of 143 strains of Staphylococcus aureus were positive for protein A, whereas all 34 strains of Staphylococcus hyicus and 123 of 127 strains of Staphylococcus intermedius were devoid of this cell wall component.