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Scientists uncover how E.coli survives in a cow’s intestine

New international research, involving the Université de Montréal, may have found a way to reduce O157:H7 in cows – thereby reducing human infections


An international consortium of scientists may be the first to demonstrate how the E.coli bacterium is able to survive in a cow’s intestine, reports the Université de Montréal.

The researchers, from the UdeM and the National Institute for Agronomic Research in France, explain that the cow’s intestine is a competitive environment and yet E.coli is able to scavenge for specific food sources. The study may lead to non-medicinal methods that can eradicate this invasive bug.

The results of their study were published in Environmental Microbiology in November.

The researchers say they studied E.coli O157:H7 because it is the most prevalent species of bacteria and it’s been associated with some of the larger, more recent outbreaks.

Those outbreaks have all been associated with a food product that has had direct contact with the farm environment, such as meat, raw milk and dairy products, for example.

The scientists explain that the cow’s intestine is a complex environment with a high number and diversity of bacteria. Most of these bugs are not harmful and many contribute to proper bowel function.

However, they explain, the intestine is also a battleground for wars between these species as they each struggle to obtain carbon, nitrogen and other sources of energy.

Those bugs that win the battle for resources survive and multiply while the losers disappear.

The scientists demonstrated that O157:H7 does in fact thrive in the bovine intestine. So they went on to determine why it does.

They found that O157:H7 is unusual because it can forage nitrogen from ethanolamine, a chemical present in the cow’s intestine.  And because other bacteria cannot process ethanolamine, O157:H7 has this source of nutrition to itself. This ability gives the bug a competitive advantage.

The final step for the scientists was to determine how O157:H7 was able to process ethanolamine so that it can be used as a nitrogen source. Genetic analysis revealed that O157:H7 has specific genes that allowed it to do so.

“We now know that this bacteria has evolved a genetic program that allows it to process ethanolamine and therefore out compete its neighbours and survive and multiply in the intestine,” says Josée Harel, co-author of the study and director of the Groupe de Recherche sur les Maladies Infectieuses du Porc at the Université de Montréal’s Faculty of Veterinary Medicine.

“This new-found knowledge will help us select appropriate feed or probiotics in an attempt to eliminate the food source of this contaminating bug. This in turn, should limit the spread of this bug into the food chain.”

E.coli O157:H7 can cause HUS or haemolytic uremic syndrome (also known as Hamburger disease). It can result in the destruction of cells that cause clotting of the blood and red blood cells. Kidney failure may result due to the damage of the small blood vessels and tubules in the kidneys. It usually affects children between the ages of 1 and 10 years, but may also occur in adults. HUS affects two to four people per 100,000 and occurs all over the world.