The major bovine mastitis pathogens have different cell tropisms in cultures of bovine mammary gland cells

We previously showed that Staphylococcus aureus cells adhered mainly to an elongated cell type, present in cultures of bovine mammary gland cells. Mor eover. we showed that this adhesion was mediated by binding to fibronectin. The same in vitro model was used here, to study adhesion of other importan t mastitis pathogens. Like the S. aureus strains, the Streptococcus dysgala ctiae strains adhered mainly to elongated cells, which seemed to be mediate d by fibronectin binding. In contrast, Streptococcus uberis strains adhered mainly to cubic cells. Since the cubic cells did not express fibronectin a nd S. uberis cells bound fibronectin less efficiently, the adhesion of S. u beris cells was independent of fibronectin binding. Streptococcus agalactia e strains adhered poorly to both cell types. The specificity and efficiency of adhesion of Escherichia coli strains was strongly strain dependent. Non e of the S, agalactiae and E, coli strains tested was able to bind fibronec tin efficiently. The results suggest that the different mastitis pathogens have different target cell specificities and use different mechanisms to ad here to cells of the bovine mammary gland. (C) 2001 Elsevier Science B,V. A ll rights reserved.