Tuesday, November 18, 2008

Skin ecology

You'll likely be wanting to wash your hands after reading this.

I continue to be fascinated with the fact that we do not walk through this world alone . . . we have a host of bacteria and other tiny organisms living in us and on us. The ecological balance of these diminutive communities is crucial to our good health. In my opinion, the body's management of microbial flora is an important part of our defensive strategy against infection.

The general public is slowly becoming aware of the importance of an ecologically balanced flora in and on the body. Witness the ongoing campaigns marketing the various health benefits of the bacterial colonies in yogurt.

A new study published in the Proceedings of the National Academy of Sciences focuses on the ecology of human skin. Researchers surveyed the DNA of bacteria present on the hands of 51 male and female subjects and come up with some interesting results . . .

Here are a few interesting data discovered by the researchers:
  • Females have a higher diversity of bacteria on their hands than males . . . perhaps due to a slightly higher skin pH in women, or perhaps the mix of sebum, sweat, and lotions, or maybe even hormonal differences . . . they couldn't really say for sure at this point
  • Females have more bacteria living under the surface film of skin than males
  • 4, 742 different species of bacteria were found in the whole group of subjects
  • The species each of has on our hands is a rather unique mix--only 5 (out of 4,742) species were found on every hand in the group
  • Most of the 150 or so different species of bacteria found on skin of an individual hand are beneficial or harmless . . . only a small minority are pathogenic
  • The diversity of bacteria differs between a person's right hand and left hand
  • Hand washing (as practiced in this group) did not remove many of the bacteria (or the populations recovered rapidly after washing)
Want to know more?

The influence of sex, handedness, and washing on the diversity of hand surface bacteria
Noah Fierer, Micah Hamady, Christian L. Lauber, and Rob Knight
published 12 November 2008, 10.1073/pnas.0807920105

[This is the original article]

Hands down, women lead in diversity of bacteria
Randolph E. Schmid
The Seattle Times (online). November 4, 2008.
[Summarizes some of the results of the study.]

The Bacterial Flora of Humans
Kenneth Todar
Todar's Online Textbook of Bacteriology. University of Wisconsin-Madison. Accesseed 5 November 2008.

Scientists work at recruiting "good bugs"

Robert S. Boyd
The Seattle Times (online). November 5, 2008.
[Summarizes current research with engineered "probiotic" beneficial bacteria to treat or prevent disease; cool image of MRSA bacteria]

Click this thumbnail for a FREE image of the skin structure that you can use in your course!

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