Skin and Wound Cultures
A skin or wound culture is a test to find and identify germs (such as bacteria, a fungus, or a virus) that may be growing on the skin or in a wound. A sample of skin, tissue, or fluid is collected from the affected area and placed in a container with a substance (called growth medium or culture medium) that helps organisms grow. If nothing important grows, the culture is negative. If something that can cause infection grows, the culture is positive. The type of organisms may be identified with a microscope, chemical tests, or both.
Most bacteria can grow in oxygen. They are called aerobic bacteria and usually are found in wounds close to the skin surface (superficial). Bacteria that cannot grow in the presence of oxygen (anaerobic) usually are found in deeper wounds and abscesses. A wound culture can find out whether bacteria are aerobic or anaerobic.
A fungal culture is done to find out if an infection is caused by a fungus. A viral culture can be done to find out whether an infection is caused by a virus.
Some types of bacteria that normally live on or in the body can cause an infection if they go to parts of the body where they are not normally found. For example, E. coli bacteria are normally found in the colon and anus. But if E. coli bacteria spread from the anus to the urethra, the bacteria may cause a urinary tract infection (UTI).
If a skin or wound culture is positive, other tests may be done to help choose the best medicine to treat the infection. This is called sensitivity testing.
Culture samples may also be collected from the ear or eye, from open or closed sores, or from nails and hair.
Why It Is Done
A skin or wound culture is done to:
- Find the cause of an infection in a sore, burn, surgical wound, or injury. An injury includes animal bites, human bites, marine stings or scrapes, cuts, and puncture wounds that are more likely to get infected.
- Make decisions about the best treatment for an infection. This is called sensitivity testing.