Molecules in meat increase E.coli susceptibility

An international research team found that toxins secreted by E.coli bacteria specifically target a sugar molecule called N-glycolylneuraminic acid (Neu5Gc) and bind to it in order to enter human cells. Humans do not naturally produce this sugar, but scientists discovered that we can absorb it by consuming red meat.

Once they enter human cells, E.coli toxins can cause causing bloody diarrhoea and a potentially fatal disease called haemolytic uraemic syndrome (HUS), which leads to acute liver failure. HUS is known as the 'hamburger disease' because humans usually become infected after eating contaminated meat.

"Ironically, humans may set themselves up for an increased risk of illness from this kind of E.coli bacteria, present in contaminated red meat or dairy, because these very same products have high-levels of Neu5Gc," explained Ajit Varki, medicine professor at the University of California, San Diego School of Medicine. "The Neu5Gc molecule is absorbed into the body, making it a target for the toxin produced by E.coli."

The Neu5Gc molecule is abundant in meats such as pork, lamb and beef and in dairy produce. When eaten, the sugar is stored in human tissue, the stomach or kidney cells. "Thus, through regular dietary intake of red meats and milk, humans may pre-sensitise their tissues to a key virulence factor of a major pathogen that occurs sporadically in the same foods," the researchers write.

Varki said the study, which was published in the London science journal Nature, emphasised the need for people to eat meat that has been well cooked, as the cooking process destroys the contaminating bacteria.

The research was funded by the National Institutes of Health and by Australia's National Health and Medical Research Council.

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