Why is raw ground beef so likely to be contaminated?
Cattle are known to be the largest reservoir of E.coli 0157:H7 and they carry the bacteria in their lower intestines. When the cattle are slaughtered the intestines can be split open and the bacteria are spread onto the carcass itself. This means that a piece of steak or a roast can carry these bacteria, but only on the outside. When you cook that steak or roast, the outside part carrying the bacteria is cooked the most, so the bacteria are killed. When raw contaminated meat is ground, the bacteria is distributed throughout the meat. So you now have bacteria on the outside as well as the inside of a raw ground meat patty. Thick, frozen hamburgers are a particular concern since its difficult to cook the inside without burning the outside. It is important to have thinner hamburgers, and if the hamburgers are frozen to thaw them in the fridge prior to cooking, and to make sure there is NO pink showing after cooking.
