ADAM Health Encyclopedia

Stool C. difficile toxin

Definition

The stool C. difficile toxin test detects harmful substances produced by the bacteria Clostridium difficile (C. difficile) in a stool sample. This bacteria is a common cause of diarrhea after antibiotic use.

Why the Test is Performed

The test may be done when your doctor suspects that diarrhea is the result of recent antibiotic use. Antibiotics alter the bacterial flora in the colon ("helpful bacteria"), and this sometimes results in excessive growth of C. difficile and its toxins. Diarrhea caused by C. difficile following antibiotic use occurs frequently in hospitalized patients.

How the Test is Performed

A sample of a stool is submitted for laboratory analysis. There are several laboratory methods used to detect C. difficile toxin in the stool specimen.

Today, an enzyme immunoassay (EIA) is most often used to detect subtances produced by the bacteria. The EIA is faster that previous culture tests, simpler to perform, and results are available in about an hour. However, it is slightly less sensitive than previous methods. Several stool samples may be needed to obtain an accurate result.

How to Prepare for the Test

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. After collecting the sample, you put it in a clean container.

Do not mix urine, water, or toilet tissue with the sample.

For children wearing diapers, you can line the diaper with plastic wrap. If the plastic wrap is positioned properly, mixing of urine and stool can be prevented for a better sample.

How the Test Will Feel

There is no discomfort.

Risks

There are no risks associated with testing for C. difficile toxin.

Considerations

Since the test for C. difficile toxin is not 100% sensitive, several stool samples may be needed to detect it.

Normal Results

No C. difficile toxin is detected.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

Abnormal results mean that C. difficile toxins are likely present in the stool and are causing diarrhea.