Virulence properties of Escherichia coli isolated from clinical bovine mastitis

The aim of this study was to detect the presence of the genes for some virulence factors in Escherichia coli isolates from clinical bovine mastitis. A total of 100 E. coli isolates, each isolated from individual cows in different herds between 2000 and 2005, were examined. Two multiplex polymerase chain reaction (PCR) assays were used to detect the presence of the genes encoding Shiga toxins I and 2 (stx1 and stx2), intimin (eaeA), heat-stable enterotoxin a (Sta), and F5 (K99), F41, and F17 fimbriae. In the PCR assays, 9 isolates were positive for the genes of F17 fimbriae and only 1 isolate was positive for the eaeA gene. The results demonstrated that none of the potential virulence factors investigated was commonly observed in E. coli isolates from bovine clinical mastitis. Shiga toxin-producing E. coli (STEC), which is potentially pathogenic for humans, was not detected by PCR among the isolates from the cases of bovine mastitis.