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Fecal culture

Definition

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 directly and others cause symptoms through toxins they produce.

How the test is performed

For 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.

For infants and young children in 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.

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.