This is really sort of a post to drive home the fact that bacteria are not the great enemy of mankind that the Victorians and the heirs to the Victorians have propagated for more than a century. If they were, we'd need to circumcise armpits and fingernails and vast swaths of the human body. An excerpt:
Furthermore, the microorganisms have evolved to exploit the unique attributes of those body parts they call home, according to a study to be published Friday in the journal Science.
Some thrive in the desert of the forearm. Others are happiest in the tropical rain forest of the armpit.
The study, conducted by a team of researchers from the National Institutes of Health, reflects a growing realization that bacteria have colonized us inside and out -- and that their presence is not only harmless but also probably essential to the proper functioning of the body.
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Among the more than 19 square feet of skin on a typical adult, the NIH team focused on 20 specific areas, ranging from the oily patch between the eyebrows to the moist space between the toes.
Senior author Julia Segre and her colleagues used Q-tip-style swabs to gather bacterial samples from 10 racially diverse volunteers, half men and half women. They collected 112,283 organisms altogether.
The specimens were classified according to a gene known as 16S rRNA, which is easy to identify and gives each bacterial species a unique signature. More than half belonged to one of three big groups that made them a cousin either of the bacterium that causes acne; one that causes diphtheria; or Staphylococcus aureus, the culprit behind many dangerous antibiotic-resistant infections.
Moist areas -- such as the belly button and the inner bend of the elbow -- have up to 10 times as many bacteria per square inch compared with dry areas, like the inside of the mid-forearm, the scientists found.
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Roughly 100 billion individual bacteria live on skin, and when you add all their genes together they dwarf the 20,000 contained in the human genome, researchers said.
The microbes are probably doing something useful, said Dr. Martin Blaser, a microbiologist and infectious disease specialist at New York University Medical Center, who in his own studies has identified 183 different kinds of bacteria on human arms.
After all, the locations of bacterial species is relatively consistent from person to person, perhaps implying some function that confers a benefit to the host.
"I can't prove it, but I think the idea that they are just hanging out is completely incorrect," Blaser said.
Segre agreed that bacteria have been getting a bad rap.
"We have to lose this language of warfare," she said. "Our goal is to keep the bacterial ecosystem in balance and move away from the concept that all bacteria are bad."
Link: Study finds 1,000 species of bacteria on healthy humans - Los Angeles Times
