MadSci Network: Medicine

Re: How do you get skin infections?

Date: Thu Mar 9 10:58:40 2000
Posted By: John Carlson, Medical student, MD/PhD (parasitology) , Tulane University, School of Medicine
Area of science: Medicine
ID: 950552906.Me

Dear Kia,

Thank you for your questions about skin infections. Skin infections are caused by tiny bacteria. These bacteria and how they cause infections are very interesting.

What kind of bacteria cause skin infections? Skin infections can be caused by many different kinds of bacteria. The most common kind is named Staphylococcus epidermis, but most people call it Staph for short.

Where does Staph come from? Everybody has Staph bacteria all over their bodes! These bacteria live there all the time. Some will even stay on your skin after you take a shower! Everyone has Staph on their bodies, but not everyone has infections.

How does Staph cause infections? Our skin is an amazing organ. It can do so many things! One important job of skin is to keep bacteria on the outside of our bodies. Usually it works very, very well. Sometimes, however, the skin breaks, like when you fall and scrape your knee, or cut yourself on a sharp object.

When your skin breaks, the Staph bacteria get inside your body. Fortunately, we have a very powerful immune system to stop bacteria that get past our skin. But sometimes the bacteria are very difficult to stop once they're under the skin. They keep growing and growing, which causes damage to our bodies.

You have an infection from the time the bacteria get under your skin until the time your immune system kills all of the bacteria. Signs that your immune system is working against bacteria that got under the skin include redness, swelling, and tenderness. If an infection gets out of control, your body may even turn up your temperature to help stop the bacteria. (Hopefully you would have seen a doctor to help you as soon as you saw the redness, so that you wouldn't have gotten to this dangerous stage of skin infections.)

Can band-aids prevent infections? Most infections are caused by bacteria that enter your wound right when you get cut. So a band-aid would not stop the infection from starting. However, a band-aid might be a good idea to prevent dirt from getting into the cut, which could make the situation worse. A band-aid might also help hold the skin together in case you bump your cut before it's healed enough to hold together. If the cut reopens, then bacteria might get into it and start an infection. On the other hand, fresh air also helps keep the wound from getting too damp, and stops bacteria from growing quickly. Different people use band-aids at different times.

Do scabs prevent infections? The main purpose of a scab is to plug up the cut to stop it from bleeding. However, it also helps to cover the scrape or cut and prevent the wound from reopening. If the wound reopens, more bacteria might get inside, and cause an infection. Scabs are definitely good to help your skin heal quickly, so it's better to leave them on as long as possible.

Why does it hurt when you wash a cut? There are many nerves in your skin. Some of those nerves are deeper inside your skin than others. Some of the deep nerves are pain nerves. It is the job of these pain nerves to let you know when you have an injury to your skin. When you wash your cut, the water presses on these pain nerves, and causes you to feel pain. It is important to keep your scrapes clean, so you may need to wash them every once in a while.

Information about how to care for your cuts and scrapes can be found on the web site of the University of Iowa's School of Nursing

You might also find these MAD Scientist essays interesting:

What kind of bacteria is under your fingernails?

What kind of bacteria grows in your hair?

Which types of bacteria are most commonly found on the human hand?

How many microorganisms do we have on the surface of our skin?

I find infections very interesting. If you would like to know more, please ask MadSci Network more questions!

Sincerely yours,

John Carlson
MAD Scientist

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