The fibronectin binding proteins of Staphylococcus aureus are required foradhesion to and invasion of bovine mammary gland cells

We recently described adhesion to and invasion of bovine mammary gland cell s by Staphylococcus aureus in vitro. Here, we show that the levels of adhes ion and invasion are dependent on the bacterial growth phase and are contro lled by the agr locus. Incubation of exponential growth phase cells of S. a ureus with mammary gland cells resulted in bacterial cell clumping. Strains of S. aureus deficient in expression of the fibronectin binding proteins ( FnBPA and FnBPB) failed to clump and their ability to adhere to and to inva de the bovine mammary gland cells is strongly reduced. This indicates that the fibronectin binding proteins are essential for S. aureus adhesion to an d invasion of bovine mammary gland cells. (C) 1999 Federation of European M icrobiological Societies. Published by Elsevier Science B.V. All rights res erved.