Intimate Strangers

I'm scanning the science news this morning, and come up with 2 similar stories in Science and the New York Times. There's an effort out to identify the majority of the bacteria that live on human skin.

Ewwww, you might say, but not so fast.

These are, for the most part, commensal bacteria. Meaning, they live on and in us with no bad effects. In fact, we WANT them there. They physically block "bad" bacteria from hooking on for a ride. Or they can make the environment a less acceptable place for the disease causers to establish a place.

We peacefully co-exist with our bacteria. There are 10 times as many bacterial cells on and in each of us than there are human cells that make us up. We're talking trillions of bacteria. Each of us is an ecosystem unto ourselves. We are made up of multiple trillions of cells of many different varieties and biological kingdoms. The vast majority of the microbes in the world are beneficial or neutral. They break down waste products, provide us with vitamins, and make the world a much more habitable place.

But scientists are trying to understand what types of bacteria colonize human skin naturally. Scientists at the U.S. National Institutes of Health (NIH) are sampling different areas of the body to find out what average, healthy people carry. Strangely enough, they've discovered that the space between your toes is a barren wasteland for bacteria--they just don't go there. However, elbows, Some of them have been known, such as Staphylococcus aureus, which can be a disease causer, but not all the time. The NIH study has found that 90% of the bacteria they're finding belong to the genus Pseudomonas which is a common soil bacterium, but not known to inhabit skin before.

Moreover, the types of bacteria that are on us differ depending on where on the body you sample. So, the bacteria are picky as to what areas they inhabit. The bacteria on the inner elbow, for example, are of different species from the ones a few inches away on the forearm.

Now, why do they want to know which bacteria inhabit the skin? Well, beyond the fact of it's just good to know what you're dealing with, it might be good to find out at some point if the microbial content differs in people with skin conditions (such as eczema). If there is a difference, perhaps that information could be used for better treatments for those skin conditions.

For more information on this work, here's the link to the NY Times article on it. More links to follow if you're not registered on the Times site.