Some factors affecting selective adherence of microorganisms in the bovine mammary gland.

Some parameters affecting the adherence of microbes to the ductular epithelium of the bovine mammary gland were studied. Adherence increased from teat sinus to lactiferous sinus to the large ducts, and cells from the lactiferous sinus to the large ducts, and cells from the lactiferous sinus were used for all other experiments. There was no difference in adherence to cells from different quarters of the same cow, but there were significant differences between cows. Scanning electron microscopy suggested that the cells of the ductular epithelium undergo dynamic changes that probably result in secretion and/or desquamation. Adherence to cells could be demonstrated only at a late stage of these changes. The adherence of organisms associated with mastitis was studied using an in vitro test. Adherence generally paralleled prevalence as cause of disease, with Staphylococcus aureus and Streptococcus agalactiae adhering best. Strain variation suggested that virulence was related to adherence with S. agalactiae and S. dysgalactiae but not with S. aureus. It is proposed that specific adherence is an important aspect of pathogenesis of mastitis due to S. aureus and S. agalactiae.