The NY Times has a pretty incredible article on why E-Coli keeps showing up in ground beef.  The whole article is worth reading, but this bit gives you the flavor of it.

The frozen hamburgers that the Smiths ate, which were made by the food giant Cargill, were labeled “American Chef’s Selection Angus Beef Patties.” Yet confidential grinding logs and other Cargill records show that the hamburgers were made from a mix of slaughterhouse trimmings and a mash-like product derived from scraps that were ground together at a plant in Wisconsin. The ingredients came from slaughterhouses in Nebraska, Texas and Uruguay, and from a South Dakota company that processes fatty trimmings and treats them with ammonia to kill bacteria.

Using a combination of sources — a practice followed by most large producers of fresh and packaged hamburger — allowed Cargill to spend about 25 percent less than it would have for cuts of whole meat.

Those low-grade ingredients are cut from areas of the cow that are more likely to have had contact with feces, which carries E. coli, industry research shows. Yet Cargill, like most meat companies, relies on it suppliers to check for the bacteria and does its own testing only after the ingredients are ground together. The United States department of Agriculture, which allows grinders to devise their own safety plans, has encouraged them to test ingredients first as a way of increasing the chance of finding contamination.

Unwritten agreements between some companies appear to stand in the way of ingredient testing. Many big slaughterhouses will sell only to grinders who agree not to test their shipments for E. coli, according to officials at two large grinding companies. Slaughterhouses fear that one grinder’s discovery of E. coli will set off a recall of ingredients they sold to others.

While none of this surprises me, since I’ve been listening to the Omnivore’s Dilemma recent, it definitely adds weight to getting your meat local, fed by what the animal evolved to eat, from farmers you trust.  It costs a bit more, but then again I tend to like my meat as free of feces as possible.