A colonic tissue culture is a laboratory test to look for disease-causing bacteria, fungi, or viruses in a sample of tissue from the large intestine.

The doctor removes a piece of tissue from your large intestine during a colonoscopy. For more information on how this procedure is done, see colonoscopy.

The sample is sent to a laboratory where it is placed in a special dish (called a culture media) and stored at different temperatures. The laboratory team checks the sample daily to see if a bacterium, virus, or fungus has grown.

If certain microorganisms grow, more tests will be done to further identify them. This helps determine the best treatment.

There is no specific preparation needed for a culture. For information on how to prepare for the procedure to remove a piece of tissue from your large intestine, see colonoscopy.

The laboratory culture does not involve the patient, so there is no pain.

For information on how it will feel to have a piece of large intestine tissue removed, see colonoscopy.

Your doctor may order this test if you have signs or symptoms of an infection that can affect the large intestine. A culture is often done when other tests such as a stool culture could not identify the cause of infection.

A normal result means that no disease-causing organisms have grown in the laboratory dish.

Some "healthy" bacteria, called bowel flora, are normally found in the gut. The growth of such bacteria during this test does not mean there is an infection.

An abnormal result means that disease-causing organisms have grown in the laboratory dish. Such organisms may include:

• Clostridium difficile bacteria
• Cytomegalovirus
• Mycobacterium tuberculosis bacteria
• Salmonella bacteria
• Schistosomiasis parasite
• Shigella bacteria

These organisms may lead to infectious diarrhea or parasitic and viral infections involving the colon.

A colonic tissue culture poses no risks to the patient. For information on risks related to removing a sample of tissue from the large intestine, see colonoscopy.