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Researchers Say Human Skin Populated by Bacterial 'Zoo'


Researchers have conducted a study of human skin and discovered at least 250 species of bacteria dwell on its surface, including some that no one knew about. But as VOA's Jessica Berman reports scientists say there's no need for alarm.

Skin is our largest organ and, until now, it has been unstudied terrain, according to Martin Blaser, a professor of microbiology at New York University.

"There has been work done in the mouth, intestinal tract, vagina. We've been involved in studies in the stomach and in the esophagus. And I wanted to turn to the skin because it's been largely been unexplored," he said.

In the first study of its kind to hunt down what, in Blaser's words, turned out to be a "virtual zoo" of bacteria that live on the skin, investigators swabbed the inner arms of six healthy volunteers, three men and three women.

Investigators discovered 182 bacterial species. Four of the volunteers were followed up several months later, the researchers detected an additional 65 microbes, bringing the total closer to almost 250.

"That's about as many species [as] are in a zoo, and this is from six people. And it's only from one site, which is an area of the forearm. So, we think this is indicative of a tremendous diversity of microbes on human skin," he said.

The findings are published in Proceedings of the National Academy of Sciences.

Blaser and colleagues found that some of the microbes were more or less permanent. Others disappeared over time.

They also discovered eight new microbes that had never been seen or described before, something Blaser says is not uncommon in studies of other human organ systems.

While it is true that many bacteria make you sick, Blaser says, people should not be alarmed about the number of microbes that inhabit the human body, estimated to be 10 times the number of human cells.

"Most of the bacteria that are present in the human body are beneficial. They are helping us. So, we want to understand these beneficial organisms much better so that we may be able to harness them some of the molecules that communicate with human cells so that we have better medicines," he said.

Blaser says future studies will focus on microbes of the skin that may be useful in curing such diseases as psoriasis.

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