EFFECT OF ABRASION OF TEAT ORIFICE EPITHELIUM ON DEVELOPMENT OF BOVINE STAPHYLOCOCCAL MASTITIS

The predisposing effect of teat damage on mastitis caused by staphyloc occi and the pathogenicity of Staphylococcus aureus, Staphylococcus hy icus, and Staphylococcus epidermidis were investigated with an experim ental model. The study included three experiments in which the teat ca nal orifice of 5 cows was slightly abraded. Experimental and control q uarters were challenged with a staphylococcal suspension, and the stat us of the quarters was monitored. Virulence of the staphylococcal stra ins was studied using a protein-binding test with I-125-labeled protei ns (fibronectin, fibrinogen, vitronectin, collagen type I and II, and IgG). Abrasion on the teat orifice epithelium was a predisposing facto r for staphylococcal infections. Teat canal infection or colonization developed in 93% of experimental quarters and in 53% of control quarte rs; IMI developed in 73% of experimental quarters, but in none of the control quarters. Quarter IMI developed more consistently when the con taminating agent was S. aureus. Staphylococcus hyicus was very effecti ve in causing teat canal infections, but S. epidermidis appeared to be less infectious. The S. aureus strain had strong binding sites for mo st of the proteins tested. The S. hyicus and S. epidermidis strains sh owed no binding, or only very weak binding, which correlated with lowe r infection rates.