Effects of fibronectin on the compact colony formation in staphylococci

Fifty-two unencapsulated strains of Staphylococcus aureus, including strains of Wood 46 and Cowan I, formed compact colonies in fibronectin -soft agar. However, 20 encapsulated strains of Staphylococcus aureus and 50 strains of Staphylococcus epidermidis showed diffuse growth in the medium. The results suggest that another possible cellular factor, other than protein A, is involved in the binding of the cell surface with fibronectin and that it would be one of factors in forming compact colonies in serum-soft agar.