Published on 02/23/01

Scientists Use Bacteria to Stop E. Coli

Researchers are confident they've found a way to dramatically reduce E. coli, one of the nation's deadliest food-borne pathogens, where it starts.

Food scientists at the University of Georgia Center for Food Safety in Griffin, Ga., have isolated beneficial bacteria in some cattle's intestines. Feeding cultures of these bacteria to cattle, they say, dramatically reduces E. coli both in their intestines and their feces.

E. coli Lives in Cattle

E. coli lives in the gastrointestinal tract of cattle and is shed in manure. The manure then spreads onto animal hides and into farm environments: drinking water for animals and irrigation water and soil used for growing crops.

The traditional method of vaccinating animals to prevent their carrying E. coli doesn't prevent their shedding it in feces. "Our new probiotic treatment shows great promise in this area," said CFS Director Mike Doyle.

The university has received a patent for the cultures. The U.S. Food and Drug Administration must now review the new treatment method. If the FDA approves, the cultures can be made commercially available as a treatment in cattle feed.

Beneficial Bacteria

Funded in part by the FDA, the UGA studies took advantage of what was already working.

"We examined about 1,200 bacteria isolated from cattle that didn't carry E. coli O157:H7," Doyle said. "We looked for beneficial bacteria that prevent E. coli O157:H7 from being carried in the intestinal tract of cattle."

The resulting probiotic bacterial culture was fed to weaned calves and adult cattle. The treatment dramatically reduced the carrying and fecal shedding of E. coli. It eliminated E. coli O157:H7 from 80 percent to 90 percent of the treated cattle.

Reduces Human Risks

The Centers for Disease Control and Prevention estimate 100,000 cases of food-borne illness are linked to enterohemorrhagic E. coli each year. The CFS culture suppresses E. coli O157:H7, the deadliest type, along with some other strains.

"As best we know, cattle are the principal source of enterohemorrhagic E. coli," Doyle said. "By reducing the amount of harmful E. coli they carry, we can reduce the environmental exposure of people to these pathogens."

Farm, Petting Zoo Visits

Most E. coli-related illnesses can be traced back to eating undercooked hamburgers. But exposure to cattle manure on the farm, Doyle said, is also a contributing factor.

"More and more, we're seeing that food is not the sole vehicle that carries enterohemorrhagic E. coli," Doyle said. "Being exposed to animals, primarily cattle, and their manure is an important factor."

Ruminating animals like cattle, goats, deer and sheep all carry E. coli, Doyle said. Visits to farms and petting zoos continue to be linked to outbreaks of E. coli illnesses.

"People have to remember that these animals often lie on their manure, which clings to their hair and hides," he said. "A recent outbreak in Pennsylvania, where several children were infected by E. coli, was associated with a farm visit."

For more information on E. coli and other food safety issues, see the CFS Web site at www.griffin.peachnet .edu/cfsqe/).

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.