Cell tropism of Staphylococcus aureus in bovine mammary gland cell cultures

Staphylococcus aureus is one of the most important pathogens of the bovine mammary gland. The interaction of S. aureus with cells of the bovine mammar y gland is considered to play an essential role in the pathogenesis. In thi s study, we identified a new target cell for S. aureus adhesion and invasio n. For that purpose, cells which compose the alveoli of the mammary gland w ere cultured. In these cultures, two morphologically different cell types, elongated and cubic cells, were observed. Adhesion and invasion of S. aureu s was studied using microscopical and microbiological methods. S. aureus ad hered specifically and in large numbers (about 300 bacteria/cell) to the el ongated cell type. No adhesion to the cubic cell type was observed. In addi tion, bacteria were also found intracellularly in the elongated cells, and enclosed in membrane vesicles. Adhesion and invasion were time dependent an d reached maximum levels after 4 h. Invasion was strongly reduced by stauro sporine and genistein. The newly identified target cell was further charact erized. (C) 1999 Elsevier Science B.V. All rights reserved.