Virulence determinants of Escherichia coli isolated from milk of sows with coliform mastitis.

Escherichia coli isolates recovered from the milk of sows with coliform mastitis were examined to determine their biochemical and serologic characteristics, serum resistance and ability to adhere to fibronectin and bovine fetal fibroblasts. No common biotype was identified, and a variety of serovars were detected. Ninety-five per cent of the investigated strains were serum resistant in swine serum. Binding to fibronectin was demonstrated in most of the strains. At a binding level above 13% of the added fibronectin the strains also adhered to fibroblasts. The results of the study indicate a galactogenous route of infection. The importance of the identified virulence factors need to further elucidated.