Cowpies and Heparin

Heparin blocks E. coli O157:H7 binding in cattle

Bacteria bind to human cells via the sugars (oligosaccharides,e.g. heparin) and proteins on their surfaces. It is advantageous to keep bacteria that are potential pathogens moving through our gut. Thus tears containing bacteria swept from our eyes and mucous with bacteria swept from our lungs end up being swallowed and passed through our digestive system. Pathogens are adapted for their ability to stick to and penetrate the layer of cells on the surfaces of our body.

We need E. coli bacteria in our bowels to digest molecules in our diet and produce vitamins. Beneficial bacteria are called probiotics. But some strains of the E. coli have been produced in cattle under conditions that favor the production of nasty toxins. This is what I think happens. Cattle secrete heparin along the full length of their gut (pig or cattle intestines are the primary source of commercial heparin) and this blocks binding of pathogens that require binding to the heparin on the surface cells. The bacteria that are normally present in the complex digestive system of cattle are disrupted by routine use of antibiotics and altered feedstock. The net result is that the bacteria that normally coat the rectal area of the cattle, which lacks heparin production, are eliminated by antibiotics and are replaced by E. coli that has picked up a gene for secretion of a toxin normally produced by a bacterial pathogen. The toxin is required to induce the release of nutrients required by the new strain of E. coli. This new strain also produces a protein, hemagglutinin, that binds to the heparin immobilized on the surface of the rectal cells. Thus, cattle raising approaches have created a new pathogen, E. coli O157:H7.

When cattle produce cowpies, the rectal bacteria coat the cowpies. As a result, the screening of the surface of cowpies can identify the presence of cattle contaminated with the toxin-producing E. coli strains. During the processing of these cattle or others splashed with the toxin bacteria, the bacteria can be spread to meat, enter our food and be spread to people. I think that the increase of chronic inflammation in the U.S. population makes us particularly susceptible to this type of pathogen. Improved hygiene will help, but changes in animal husbandry may be the ultimate solution.