The FDA just issued a "Barbecue Basics" health alert in advance of the holiday weekend. The agency offers food handling and storage tips and advises that you use a meat thermometer to ensure that you cook hamburgers to at least 160° F and chicken to at least 165° F, which will kill harmful bacteria. If you lack a thermometer, make sure hamburgers are brown all the way through, not pink.
The same advice holds when you're grilling steaks and other cuts of meat. This is especially important if you're cooking mechanically tenderized beef. During mechanical tenderizing, meat is run through a machine that punctures it with blades or needles. That process can drive bacteria, such as the deadly pathogen E. coli O157:H7, into the center of the meat, where it's harder to kill.
We suggest you cook beef to 160° F, as you would a hamburger, rather than to the 145° F (typical for medium-rare) that the USDA recommends for non-tenderized steak. Use a meat thermometer inserted into the center of the beef rather than simply judging by the color of the meat. Letting the beef rest for several minutes after you pull it off the grill or out of the oven also allows further cooking time to kill any pathogens that may remain in “cold spots” on the interior.