Bacterial adherence in mastitis caused by Escherichia coli.

The possible role of bacterial adherence in the pathogenesis of experimental mastitis in the mouse was examined with four strains of Escherichia coli. Two of these strains had a known adhesion antigen (K88) and two did not. The K88 antigen did not play a significant role in the virulence or infectivity of E. coli either in the murine or bovine mammary gland. Two E. coli strains, W1 (K88+) and J2 (K88-) were virulent in the mouse but did not adhere to epithelial cells. Both these strains produced clinical mastitis in the cow. A third strain, D282 (K88-), produced mild disease in the mouse but was avirulent in the cow. The fourth strain, 233/ID (K88+), was avirulent in both the mouse and the cow. Strains D282 and 233/1D were killed rapidly by bovine serum whilst J2 and W1 were more resistant. All strains were more sensitive than the control resistant strain E. coli P4, which is known to be highly virulent for the lactating udder.