Structural analysis of the cellular constituents of a fresh clinical isolate of Staphylococcus aureus, and their role in the interaction between the organisms and polymorphonuclear leukocytes in the presence of serum factors.

The in vitro interaction of a fresh clinical isolate of Staphylococcus aureus and polymorphonuclear leukocytes was investigated. The importance of the various cellular constituents as host immunological factors was analyzed, and the results suggested that two components, namely, an acidic polysaccharide consisting of a predominance of aminogalacturonic acid and a strain-specific mucopeptide complex, may be involved in impeding in vitro opsonization of the organism by leukocytes. Immunochemical analysis indicated that the acidic polysaccharide possessed the same immunodominant aminogalacturonic acid residues as the antiphagocytic acidic antigen of the encapsulated prototype Scott strain. Antisera derived from rabbits immunized with strain D contained two types of opsonins, those with acidic polymer specificity and those with mucopeptide complex specificity.