Escherichia coli O157:H7, (EHEC), is associated with consumption of ground beef or raw milk. Illnesses caused by EHEC infections can range from self-limited watery diarrhea to life-threating manifestations such as haemolytic-uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). The lack of efficient selective enrichment medium for EHEC, reduces the sensitivity and specificity of the conventional cultural method (CCM). Immunomagnetic separation (IMS) using Dynabeads(R) anti-E. coli O157:H7 represents the selective enrichment procedure needed to improve the CCM. On the other hand, measuring the light given off by the reaction of ATP with luciferase+luciferin reagent in relative light units (RLU), indicates the count of EHEC.