Abstract

A. Jamshidi*, H. A. Seifi and M. Kooshan

Escherichia coli O157:H7 is an important human pathogen causing haemorrhagic colitis, hemolytic-ureamic syndrom and thrombotic thrombocytopenic purpura. In this study the effect of microwave irradiation of beef samples which were inoculated with E. coli O157:H7 were investigated. The portions of fresh beef slices weighting 200 g each and about 10 × 10 × 2 cm in size, were soaked in fully growth of E. coli O157:H7, in BHI broth. The swab samples were taken from the contaminated samples, after different times of radiation (10, 20, 30, 40 and 50 s), using a domestic microwave oven at full power. The bacterial counts were performed by using surface plating on sorbitol Mac Conkey agar supplemented with cifixime and potassium tellurite. After each experiment the surface temperature of treated samples were measured. The experiment was carried out in triplicate and it was concluded that the microwave radiation which enhance the surface temperature more than 70°C, can eliminate the superficial contamination of cattle beef slices with E. coli O157:H7.