Right now your hands are teeming with bacteria. Countless trillions of organisms call your skin home, and that’s a good thing. Skin infections do not arise because you have bacteria on your skin. Rather, they arise because the type of bacteria on infected skin is not healthy bacteria but aggressive pathogenic bacteria.

Determining which bacteria are good and which are dangerous is difficult, but our immune systems have managed to get it right most of the time. When our immune systems are wrong, either an infection develops, or excess inflammation develops, as is the case in eczema or psoriasis.

Telling good from bad is hard. There are hundreds of types of bacteria on your hands right now. A recent study of college students (perhaps not the cleanest group of individuals) discovered that the average student has 140 different types of bacteria on his or her skin. There were over 4,000 different types of bacteria identified across all the students. Not surprisingly, the most common types were familiar household names: Propionobacterium (the bacteria responsible for acne), strep, and staph (of which the infamous methicillin resistant staph aureus, MRSA is a subtype).

There were also differences in the bacteria on the dominate hand versus the non-dominant hand — namely bacteria normally found in the gastrointestinal track was found more often on the dominant hand. This will no doubt lead to a follow up study of: “Do college students wash their hands before leaving the bathroom?” (Research so far does not look promising).

From Dr Benabio from the Dermatology Blog