Magazine article USA TODAY

Mechanism May Stop E. Coli in Cattle

Magazine article USA TODAY

Mechanism May Stop E. Coli in Cattle

Article excerpt

A potential target in cattle that could be exploited to help prevent outbreaks of food-borne illnesses caused by a nasty strain of Escherichia coli has been identified by microbiologists at the University of Texas Southwestern Medical Center, Dallas, working with the Department of Agriculture. In their study, researchers interfered with a genetic sensing mechanism that allows the E. coli strain known as Enterohemorrhagic 0157:H7, or EHEC, to form colonies within cattle, causing the bacteria to die off before they could reach the animals' rectoanal junction, the primary site of colonization. Most other strains of E. coli gather in the Colon.

"We're dismissing colonization by not letting EHEC go where it needs to go efficiently," explains Vanessa Sperandio, associate professor of microbiology and biochemistry. "If we can find a way to prevent these bacteria from ever colonizing in cattle, it's possible that we can have a real impact on human disease. This could be something as simple as including some sort of antagonist in cattle feed, which would result in less shedding of the bacteria in fecal matter with less contamination down the road in food products."

An estimated 70% to 80% of U.S. cattle herds carry EHEC. Although EHEC can be a deadly pathogen to humans, the bacterium is part of cattle's normal gastrointestinal flora. EHEC harbors a gene called SdiA, which makes the SdiA protein. SdiA senses a chemical made by microbes in the animal's rumen, the first of a cow's four stomachs, which serves as a large fermentation chamber. Detecting this signal allows EHEC to pass through the rumen and colonize the recto-anal junction. …

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