Phil Lempert, the Today Show’s food editor, wrote a recent article that appeared on The article, "Protect your family from Salmonella and E. coli," gave some useful pointers for preventing E. coli infection:

As we have heard in the headlines recently, it is critical to understand that meat is not the only source of contamination with E. coli or other dangerous bacteria — any contaminated water source or contaminated person can spread these bacteria onto fruits, vegetables, or any kind of foods. Be sure to wash fresh fruit and vegetables thoroughly before eating. And if you like your meat and especially hamburgers, "rare", you are taking a significant risk.

Talking about meat… one of the reasons to make sure that all meat is thoroughly cooked is that as the meat is cut with a knife (or punctured with a fork) the utensil will carry the bacterial cells down into the cut or puncture. Bacteria are microscopic so even a tiny, pretty much invisible cut in the meat could introduce bacteria inside. It’s always safest to cook all meat at least until the juices of the meat run absolutely clear — not pink.