Pathogen Reduction in E. Coli O157:H7 or Salmonella Colonized Calves

NON-TECHNICAL SUMMARY: E. coli O157:H7 continues to be a major threat to the nation's food and water supply. Cattle serve as the reservoir host for E. coli O157:H7. Methods for reducing or removing this pathogen from cattle are badly needed. The purpose of this study is to determine the effectiveness of using a naturally occurring viral predator of E. coli O157:H7 to reduce O157 shedding from colonized cattle.

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APPROACH: E. coli O157:H7-specific bacteriophage will be isolated from cattle, analyzed for receptor specificity, and tested in vitro for lytic ability against O157. Bacteriophage demonstrating the best in vitro killing will be combined into cocktails and (1) used to treat O157-colonized calves, and (2) used to pre-treat non-O157 colonized calves, followed by O157 infection. Shedding of O157 from bacteriophage-treated calves will be compared to shedding from non-treated calves. If our hypothesis that bacteriophage can be used for pathogen reduction is correct, then phage-treated calves should show reduced O157 shedding.

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PROGRESS: 2002/07 TO 2007/06<BR>
OUTPUTS: The primary outputs of this project have been in the form of scientific presentations. The investigators have presented these results to five multi-state food safety project meetings (S-1033, formerly S-313, and before that, S-295), and to three national or international meetings. An additional output includes a physical collection of bacteriophages specific for the food-borne pathogens E. coli O157:H7 and Salmonella. This collection is available to the investigators and their collaborators for continued studies on pathogen reduction in livestock. <BR> PARTICIPANTS: Stuart B. Price, Principal Investigator (PI), wrote the manuscripts and funding proposals, with help from the co-investigators. He oversaw all aspects of the project, and personally directed the portions of the project involving the microbiological techniques (isolation and culture of bacteria and bacteriophages). He supervised the research assistant and student workers involved with the project. With the help of co-investigator Wright, he prepared a procedure manual for the calf portion of the project, including the inoculation, culture, and containment of the bacterial pathogens used. He presented both poster and platform presentations of the work at local, regional, and national meetings. James C. Wright, co-investigator, oversaw the day-to-day animal husbandry involved with caring for the calves. He led the calf inoculation and bacteriophage treatment procedures. He was the primary worker involved in data analysis. He interacted daily with the PI in pursuing the many details involved in project, and helped write and review the grant proposals and manuscripts. Paul H. Walz, co-investigator, was the project veterinarian. He interacted with the other investigators and student workers in seeing to the overall health and well-being of the calves. He personally performed euthanasia on the calves. As a practicing bovine clinician, he kept the other investigators current on important topics regarding antibiotic usage and food safety in cattle, and helped with specific aim development on the funding proposals. <BR> TARGET AUDIENCES: The target audience for this project would be bovine veterinary clinicians, beef and dairy producers, and consumers interested in "antibiotic-free" beef and dairy products. <BR> <BR> IMPACT: 2002/07 TO 2007/06<BR>
Removal or reduction in number if the enteric pathogens E. coli O157:H7 and Salmonella from cattle should decrease the human disease caused by these organisms. The novel approach of using bacteriophages as a treatment to remove these bacterial pathogens from cattle was investigated in this project. Bacteriophages targeted for E. coli O157:H7 and Salmonella did decrease fecal shedding of these pathogens from calves. Reduced fecal shedding translates into decreased contamination of bovine food products. The success of this approach provides an alternative intervention to using antibiotics to treat calves. Reduced antibiotic usage in cattle will, in turn, decrease the development of antibiotic resistance in food-borne pathogens, including Salmonella. Further refinement and use of bacteriophage treatment, combined with traditional pathogen reduction techniques, will result in a safe, economically feasible approach to pathogen reduction in the animal production food safety arena.