Stool culture

Alternative names
Fecal culture; Culture - stool


A fecal culture is a laboratory test to isolate and identify organisms in the feces that may cause gastrointestinal symptoms and disease. Normally, many organisms are present in the feces, but some can act as pathogens (disease-causing organisms).

Some bacteria cause symptoms because of the toxins they produce, while other cause symptoms by direct bacterial effects.

How the test is performed
Adults and children:
There are many ways to collect the samples. You can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then, put the sample in a clean container. One test kit supplies a special toilet tissue that you use to collect the sample, then put the sample in a clean container.

Infants and young children:
For children wearing diapers, line the diaper with plastic wrap. If the plastic wrap is positioned properly, isolating the stool from any urine output, mixing of urine and stool can be prevented for a better sample.

A sample of the specimen is placed in culture media to encourage the growth of microorganisms. The culture is observed for growth at regular intervals in the laboratory. When growth is observed, the organisms are identified. Further tests to determine sensitivity of the organisms to antimicrobial therapy may also be carried out.

How to prepare for the test
A collection container will be provided for the stool specimen. Return the sample to the laboratory as soon as possible. The specimen should not include toilet tissue or urine.

How the test will feel
There is no discomfort.

Why the test is performed
The test is performed when gastrointestinal distress is present and an infection is suspected as a cause of the distress. It may be performed if severe, persistent, or recurrent diarrhea of unknown cause is present. It may also be performed when long-term antibiotic therapy has been used, to see if bacteria that don’t usually live in the intestine such as C. difficile are now in the intestine.

Normal Values
Normal fecal organisms are present.

What abnormal results mean
Abnormal results may indicate an intestinal infection (such as bacterial or parasitic enterocolitis).

What the risks are
There are no risks.

Special considerations
Often other stool tests such as gram stain of stool, stool ova and parasites exam, and fecal smear are done in addition to the culture.

Johns Hopkins patient information

Last revised: December 4, 2012
by Amalia K. Gagarina, M.S., R.D.

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