Microbes cover you inside and out and help keep you alive

September 06, 2010|By CHRIS COPLEY
  • After the use of Glo Germ.
Photos by Ric Dugan/Staff Photographer,

You are like a planet, and your skin is populated with hundreds of different species of microbes.

And that is healthy and normal.

This eye-opening perspective came from Dr. David Karstaedt, assistant professor of anatomy and physiology and microbiology at Hagerstown Community College.

"The thing that's interesting about the human body - we're completely covered in microbes," Karstaedt said. "If your body were to somehow dissolve, your friends would still recognize you. The microbes on your skin would still be there."

And that's just one of the surprises about the teeming, tiny world of microbes.

Bacteria make up a shadow self

Bacteria, along with yeast, fungi and other single-celled organisms, are part of the microscopic world of microbes. They are so small, they are invisible to the naked eye. Before the development of the microscope in the 1600s, no one knew microbes existed.

Now, researchers know we have bacteria living all over our bodies. Karstaedt said there are about 10 times as many bacteria living on and in us and there are cells in our body.


Here's a short list of bacteria that live on and in us, according to the Digital Learning Center for Microbial Ecology, a website of Michigan State University at :

  • Teeth - Streptococcus convert sugars in food to lactic acid, which dissolves tooth enamel.

  • Stomach - The stomach is acidic, and almost no bacteria can live there. But one strain, H. pylori, can adjust a stomach's acidity and survive. The bad news: This can lead to peptic ulcers. The good news: The bacteria apparently protects its host from gastrointestinal reflux disease and a form of deadly cancer.

  • Skin - Hundreds of different strains of bacteria live on our skin. Staphylococcus is the most common type and is harmless. But when it enters skin through a cut, it can cause infections, some of them serious.

  • Intestines - Two common bacteria in your intestines are E. coli and L. acidophillus. E. coli produces vitamin K and some B vitamins; acidophillus' high population helps crowd out invasive bacteria.

    Bacteria not all bad, not the same

    Dr. Paul Waldman, a Hagerstown dermatologist, distinguished between "normal flora," the microbes that are native to us, and transient bacteria that we pick up through breathing, consuming food or touching things.

    Normal flora is not a danger, Waldman emphasized.

    "The presence of bacteria doesn't indicate infection," he said. "One problem you see is some people are overzealous in cleaning or washing. Overzealous washing can lead to irritation and to an infection."

    Marjorie Kellman, lead health occupation teacher at Washington County Technical High School in Hagerstown, agreed.

    "You'd be amazed at the people who think they can sterilize their skin. They can't," she said. "And we don't want to clean everything off. Bacteria help to keep those parts clean."

    Fighting the bad-guy bacteria

    Transient bacteria, not normal flora, are generally responsible for infection and disease. Efforts to kill bacteria should aimed at these invaders, Kellman said.

    The best way to do this? Wash your hands.

    "None of my students know how to wash their hands," she said. "Handwashing with soap and water can clean everything. We've gone crazy with the antibacterials. You don't need to use them, except when you don't have soap and water."

    Soap is important. It helps lift debris from skin. It can dissolve bacterial cell walls. But soap is not the most important part of handwashing.

    Rubbing is the most important part.

    "The right way to wash is to wash your hands for 20 to 30 seconds," Kellman said. "Use lots of friction. Get under your fingernails. All the way to your wrist. Rub one hand around the opposite wrist. You have to use friction."

    Bacteria are our friends, at least sometimes

    Here are good ways to think of the distribution of bacteria on the Earth. Anywhere there is air or water, there are bacteria. You breathe bacteria. You drink bacteria. They are in your food and drink, on your cell phone, in your vehicle - virtually everywhere.

    And that's the way we like it. According to Karstaedt, humans and all other living things have evolved to live with bacteria. We need bacteria, he said. All life needs bacteria.

    Plus bacteria perform some useful tricks for humans. Bacteria curdle milk into cheese and yogurt. They turn fruit or vegetable juice into beer or wine.

    In the soil, bacteria decompose plant waste into soil. Some strains fix nitrogen in soil, without which plants could not grow.

    Some bacteria in soils and water eat petroleum. One recently discovered strain is at home in the frigid, high-pressure waters at the bottom of the Gulf of Mexico; this strain is helping clean up petroleum released during the BP oil spill.

    The bottom line is it's all part of the natural world, Waldman said.

    "After you know about natural science, you know there's microbes everywhere," he said. "It's the nature of what's there. I'm not grossed out. It's part of our world."

    Karstaedt put it succinctly.

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