Bacteriophage cocktail significantly reduces Escherichia coli O157:H7 contamination of lettuce and beef, but does not protect against recontamination

Escherichia coli (E. coli) O157:H7 is a Shiga toxin producing member of enterohemorrhagic E. coli (STEC). It is a major foodborne bacterial pathogen, which was first associated with human illness during an outbreak of hemorrhagic colitis in 1982, and has been listed by the Centers for Disease Control and Prevention as a national notifiable disease since 1994. This bacterium has been estimated to cause > 63,000 foodborne illnesses and approximately 61 deaths annually in the United States. E. coli O157:H7 infections are of particular concern in young children and elderly persons because it is associated with hemolytic uremic syndrome which may permanently damage the kidneys. In addition to being of significant importance to public health, the economic impact of E. coli O157:H7 contamination of foods is substantial. It has been estimated that hospitalizations and deaths due to E. coli O157:H7 infections in the United States may lead Foods contaminated with Escherichia coli O157:h7 cause more than 63,000 foodborne illnesses in the United States every year, resulting in a significant economic impact on medical costs and product liabilities. efforts to reduce contamination with E. coli O157:h7 have largely focused on washing, application of various antibacterial chemicals, and gammairradiation, each of which has practical and environmental drawbacks. A relatively recent, environmentally-friendly approach proposed for eliminating or significantly reducing E. coli O157:h7 contamination of foods is the use of lytic bacteriophages as biocontrol agents. We found that ecoShieldTM, a commercially available preparation composed of three lytic bacteriophages specific for E. coli O157:h7, significantly (p < 0.05) reduced the levels of the bacterium in experimentally contaminated beef by ≥ 94% and in lettuce by 87% after a 5 min contact time. The reduced levels of bacteria were maintained for at least one week at refrigerated temperatures. however, the one-time application of ecoShieldTM did not protect the foods from recontamination with E. coli O157:h7. Our results demonstrate that ecoShieldTM is effective in significantly reducing contamination of beef and lettuce with E. coli O157:h7, but does not protect against potential later contamination due to, for example, unsanitary handling of the foods post processing. Bacteriophage cocktail significantly reduces Escherichia coli O157:H7 contamination of lettuce and beef, but does not protect against recontamination