3/19/2009 10:19:00 AM 

Vaccine a breakthrough in fight against E. coli

Source of Article:  http://www.capitalpress.info/main.asp?SectionID=75&SubSectionID=767&ArticleID=49767&TM=58133.16


It's not the silver bullet, but the new vaccine that causes cattle to shed Escherichia Coli O157 bacteria as dead bits of matter comes close. Conditional approval of the vaccine developed by Epitopix, a Minnesota animal pharmaceutical laboratory, was announced earlier this month at the Beef Industry Food Safety Conference.

As we understand the science, the vaccine, administered to feedlot cattle before slaughter, interrupts the flow of iron, an essential nutrient, to E. coli living in the gut. That means that in a high percentage of treated animals, there's no living bacteria shed in manure. Epitopix hasn't set a price, but promises the per dose cost "will be reasonably priced."

From the time that the toxic strain of E. coli O157:H7 first surfaced in 1993 - traced to hamburger patties from a Washington state fast food restaurant and blamed for the deaths of four children - the beef industry, food processors and restaurant operators have invested millions of dollars in research. Discovery of contaminated ground beef has put more than one processor out of business.

E. coli is naturally occurring. Proper cooking of meat kills the organism before human consumption. The same bacteria has also, from time to time, turned up on fresh produce.

As research went forward, other subspecies of the O157 variety, in addition to H7, were found to be highly toxic to humans. That caused scientists to seek a cattle vaccine that works against known O157 subtypes.

The 2007 feedlot trials of the Epitopix vaccine were financed by the National Beef Checkoff, a $1 a head fee paid each time cattle change ownership. This amounts to a big research payoff for dairy and beef producers, who since 1993 have invested $27 million in research fighting this pathogen.

While the vaccine represents a breakthrough, drastically lowering the risk that E. coli will be shed by an animal heading for slaughter, it's no time to dismantle the elaborate set of safeguards the industry and government regulators created over the past two decades. Epitopix, in its news release announcing U.S. Department of Agriculture's conditional license for the vaccine, is very careful to use the words "reduce the prevalence" rather than "eliminate" E. coli.

USDA made the license conditional so the company and the industry can move to large-scale tests on the potency of the vaccine and be more specific on how dependable it may be. The vaccine is an extract of a bacteria that blocks iron uptake in E. coli. The first time the material was tried in a Kansas State University feedlot situation, it decreased shedding of E. coli by 54 percent. When the research team at Kansas State and West Texas A&M University increased the dose, shedding of E. coli was knocked down by 85 percent.

Guy Loneragan, who headed the Texas portion of the trials, said at a beef research meeting last year that 85 percent kill rate means handling the remaining bacterial is "within the capacity" of the suite of in-plant safety measures used by packers. They range from washing hides before and after slaughter to in-plant carcass spray washes and microbial laboratory testing during carcass handling.

Kansas State's lead scientist on the project, Dan Thompson, said of the vaccinated cattle still shedding bacteria, "we observed nearly a 98 percent reduction of E. coli O157 fecal concentration."

That's manageable at a packinghouse, but it's still no reason to let up on consumer education in proper cooking of food, nor in washing fresh produce before consumption.

 

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