The work shows the data of monitoring research on diagnosis of enterohaemorrhagic E. coli (EHEC) О157:Н7 among the cattle on the farms of Irkutsk region. For the first time the authors have used immunochromatographic method of research with the use of test-systems “E. coli О157:Н7 Test” produced by Novated Ltd (Israel). It was established that EHEC О157:Н7 can be revealed among the animals of different age groups. The work shows the results of research of susceptibility/resistance of 35 isolates. As it was established, strains of EHEC received from ill calves bear strong resistance against modern medication used nowadays to treat colibacteriosis at the farms of the region. The separated isolates possess the highest susceptibility to antibiotics of the cephalosporin group of various generations (I-IV). Experiments in vitro have shown for the first time that 62,9 % of strains are susceptible to the new veterinary medication trametin received with the use of biotechnological methods on the basis of xylotrophe fungus Trametes pubescens (Shumach.:Fr.) Pilat.