EN
A hundred of E. coli strains from 86 cows with colimastitis were screened using the PCR method for the presence of shiga toxin-producing Escherichia coli (STEC) genes. The procedure involved amplifying the stx gene (stx1, stx2) and its variants (stx2c, stx2d, stx2e, stx2f) with primers described earlier by other authors. The amplification reaction generated PCR products of molecular masses 348, 584, 124, 175, 303, 428 bp, respectively, and 798 bp for 16S rRNA E. coli as an internal control. The presence of shiga toxin genes was found in four strains (4%) and stx2, stx 2c and stx2e genes were stated. The study indicates that mastitis milk can be potentially risky for human since it is an important source of shiga toxin-producing E. coli strains.