Escherichia coli O157:H7 is a newly emerged pathogen ,recognized as a major cause of large scale epidemics and thousands of sporadic cases of gastrointestinal illness. This observation particularly calls for the in vivo examination of E. coli O157 candidates in an attempt to mimic various aspects of E. coli O157:H7 disease symptoms in humans. Healthy conventional Swiss albino mice were used for investigating the clinical manifestation exerted by stx1A and stx2A positive E. coli O157 in various doses applied through three alternative routes .The oral way of E.coli O157:H7 addition at the dose of 100 µl suspension containing 1X109CFU ml-1 was taken as the most potent concentration in producing bacterial fatality and hence was selected as the Minimum Lethal Dose. A previously characterized O157-specific lytic bacteriophage PAH6 and P2BH2 were tested, alone or in combination, for reducing intestinal Escherichia coli O157:H7 in animals to rescue the experimental murine model from lethal challenge(1X109 CFU ml-1. The result revealed in this research can be concluded that cocktail of two coliphages applied orally for treatment gastrointestinal infection have good therapeutic potential.