"If there's no signal, then there's no acid resistance, a requirement for the pathogen to make it to the recto-anal junction," Dr. Sperandio said. "Everybody had thought that this type of signaling occurred naturally in the gastrointestinal tract of mammals. Our finding serves as a proof-of-principle that we might be able to target this system to prevent food contamination."

EHEC, like other E coli strains, is usually transmitted through contaminated food. Recent outbreaks in the U.S. have been found in ground beef, spinach and raw sprouts. EHEC is responsible for outbreaks throughout the world of bloody diarrhea and hemolytic uremic syndrome - a condition that can lead to renal failure and death. Severe symptoms are most common in children, the elderly and immune-suppressed people.

Cattle are the primary source for most E coli infections in the U.S. When cattle waste reaches water sources near food crops, contamination can occur. Unsanitary slaughtering of cattle also can lead to cross-contamination of the beef itself, and shipment of infected food speeds the rate at which the public can become ill.

Dr. Sperandio said the next step is to assess what happens to cows fed a grass-based, rather than grain-based, diet.

Source: UT Southwestern Medical Center