In the July/August issue of Discover magazine there is a short article on the fact that scientists are testing whether we can be identified by the bacteria in our hands. Apparently there is some evidence to suggest that the bacteria we carry with us is unique from person to person.
I think this is another indication that we exist in homeostasis with certain bacteria. Trying to kill the bacteria all off, whether in our gut or on our body could be damaging ourselves. Consider that we are home to thousands of them, inside our gut and on our skin. We are a walking microscopic world that is different from everyone else. Our world lives because of the bacteria–and they live because of us.