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 will be identified with a microscope, chemical tests, or both.

Some organisms can grow in air (oxygen); these are called aerobic organisms. Aerobic organisms usually are found in wounds close to the skin surface (superficial). Organisms that cannot grow in the presence of oxygen (anaerobic) usually are found in deeper wounds and abscesses. A wound culture can find out whether organisms are aerobic or anaerobic.

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, 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.

How To Prepare

You do not need to do anything before you have this test. If you are taking or have recently taken antibiotics, tell your doctor.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

To collect a tissue or fluid sample from a wound, a sterile swab is inserted into the wound. The health professional collecting the sample may press around the wound and gently turn the swab to collect as much tissue or fluid as possible. The swab is then placed into either an aerobic or anaerobic culture tube or both, depending on the type of organism suspected.