The interior of a raw hamburger usually does contain bacteria, and is safest if cooked well done.. Because E. coli is killed at 155 degrees Fahrenheit, the USDA sets the minimum safe temperature for ground beef at 160 degrees Fahrenheit.We can only second this... meats inevitably harbor bacteria, and it takes temperatures of 160 degrees Fahrenheit or higher to guarantee the rapid destruction of the bacteria that can cause human disease — temperatures at which meat is well-done and has lost much of its moisture.