Beef Quality Corner:
E. Coli O157:H7 Update
Livestock Update, April 2000
Bill R. McKinnon, Extension Animal Scientist, Marketing, Virginia Tech
Human illness caused by E. coli O157:H7 continues to be a serious concern for the beef industry. It is unfortunate that in today's media culture food borne illness caused by E. coli seems immediately linked to beef. A significant number of E.coli induced illnesses have been traced to contaminated vegetables, apple cider, sloppy food preparation, etc. Illnesses caused by the organism traced to contaminated beef are generally associated with ground beef products. Cuts such as steaks and roast will be subjected to high surface temperatures during the cooking process which will kill the bacteria.
The bacteria E. coli is one of the most common groups of bacteria in the world. The organism is normally found in the gastrointestinal tract of warm blooded animals. Thousands of strains E. coli are harmless to human health. The particular organism E. coli O157:H7 was first identified in 1982. Illness caused by E. coli O157:H7 can cause hemorrhagic colitis, a disease with symptoms of bloody diarrhea and severe abdominal pain. Another severe situation than can result is hemolytic uremic syndrome, which is a leading cause of acute kidney failure in children. Humans with ineffective or compromised immune systems such as the very young, very old and previous ill are more susceptible to acute disease problems.
Sampling conducted last year demonstrated that more than half the cattle tested carried E. coli O157:H7. This has serious ramifications for the beef industry indicating the potential for significant carcass contamination. A spate of recent research may provide the industry tools for dealing with this health problem.
A recent University of Nebraska study into the genetic makeup of E. coli O157:H7 may shed some light on why there are not higher rates of human illness from the organism. The study discovered that two different populations of the organism exist. Researchers found that the strain of bacteria most commonly found in cattle is either incapable of causing illness or not easily transmitted to humans.
Other research by USDA and Cornell has discovered that sodium carbonate, an ingredient used in soft drinks and toothpaste kills E. coli O157:H7 within cattle manure. On farm testing may indicate whether sodium carbonate might be used as a feed supplement to reduce the organism population before the cattle are processed.
Research at California State Polytechnic Institute has shown that lactoferrin, a naturally occurring protein in cow's milk can control more than thirty harmful bacteria, including E. coli O157:H7. To control the bacteria in the packing plant, a small amount of lactoferrin could be applied to the surface of carcasses or meat cuts during processing. This natural protein does not affect the taste, color, or appearance of beef and may avoid some the negative consumer reaction to irradiation.
Meanwhile, Canadian scientists have created a new "starfish" molecule that may offer a cure to humans stricken by E. coli O157:H7. The complex "inhibitor" molecule essentially grabs toxin molecules and could escort them out of the body. Human tests need to be conducted to evaluate the effectiveness of the starfish molecule in preventing kidney damage.