Prevalence of virulence factor genes in Escherichia coli isolates from dairy cows with mastitis

To investigate into the prevalence of virulence factor genes in mastitis-causing bacteria and prevent bovine mastitis optimistically, one hundred and twenty three Escherichia coli isolates from bovine mastitis were examined to detect the virulence associated genes by using polymerase chain reaction (PCR) methods. The data showed that 11 virulence genes were detected, including ETT2, STb, CNF2, Tra, LTa, HPI, Hly, Aer, Pfa, Sfa and F17, and none of the isolates contained the genes for Stx2e, STa, CNF1, LEE, Afa and CS31A were found. All of the detected virulence genes were present alone or in combination with each other, there into, 87 (70.73%) isolates had at least one virulence gene, and ETT2 locus was the most common gene in the examined isolates (38.21%), followed by STb (25.20%), CNF2 (19.51%), Tra (17.07%), LTa (14.63%), HPI (14.63%), Hly (7.32%), Aer (4.07%), Pfa (2.44%), Sfa (2.44%) and F17 (1.63%).