STAPHYLOCOCCUS-SAPROPHYTICUS HEMAGGLUTININ BINDS FIBRONECTIN

Attachment of microorganisms to host tissue is regarded as an importan t step in the pathogenesis of infections. Staphylococcus saprophyticus adheres to various epithelial cells and hemagglutinates sheep erythro cytes. The hemagglutinin has been identified, but a human target for t his surface protein is still now known. In our report, we show that he magglutinating strains of S. saprophyticus bind to immobilized fibrone ctin, whereas nonhemagglutinating strains do not. Bacterial binding wa s inhibited by antibody to the hemagglutinin but not by antibody to Ss p, another surface protein of S. saprophyticus. The purified hemagglut inin but not other surface proteins bound biotin-labeled fibronectin. Binding was saturable and could be inhibited by unbound hemagglutinin, unlabeled fibronectin, and by antibody to the hemagglutinin. We thus conclude that the hemagglutinin of S. saprophyticus may act as a fibro nectin receptor in the human host. Heparin, the D3 peptide, or Arg-Gly -Asp-Ser (RGDS) containing peptides did not inhibit binding of fibrone ctin to the hemagglutinin, indicating that the binding site is differe nt from that of Staphylococcus aureus or Treponema pallidum.