• Welcome to Crohn's Forum, a support group for people with all forms of IBD. While this community is not a substitute for doctor's advice and we cannot treat or diagnose, we find being able to communicate with others who have IBD is invaluable as we navigate our struggles and celebrate our successes. We invite you to join us.

How Was Your Clostridium difficile (C. diff) Test Reported?


Crohnsforum Science Advisor
A member asked me what the test results for C. diff look like because she was wondering if she was tested for C. diff infection.

The information I have gives a TON of possible names that may be used in the report (everything from a phone call to specifics on the test and test supplier).

Can you guys help?

I will post the information I have. But I am sure yours would be more helpful. :)

Thank you so much in advance,


Crohnsforum Science Advisor
Some Info I have regarding Clostridium difficle testing (no information on test report names though):

•Stool culture for Clostridium difficile: While this is the most sensitive test available, it is the one most often associated with false-positive results due to presence nontoxigenic Clostridium difficile strains. However, this can be overcome by testing isolates for toxin production (i.e. so called “toxigenic culture”). Nonetheless, stool cultures for Clostridium difficile are labor intensive, require an appropriate culture environment to grow anaerobic microorganisms, and have a relatively slow turn-around time (i.e. results available in 48-96 hours) making them overall less clinically useful. Results of toxigenic cultures do serve as a gold-standard against which other test modalities are compared in clinical trials of performance.

•Molecular tests: FDA-approved PCR assays, which test for the gene encoding toxin B, are highly sensitive and specific for the presence of a toxin-producing Clostridium difficile organism.

•Antigen detection for Clostridium difficile: These are rapid tests (<1 hr) that detect the presence of Clostridium difficile antigen by latex agglutination or immunochromatographic assays. Because results of antigen testing alone are non-specific, antigen assays have been employed in combination with tests for toxin detection, PCR, or toxigenic culture in two-step testing algorithms.

•Toxin testing for Clostridium difficile: ◦Tissue culture cytotoxicity assay detects toxin B only. This assay requires technical expertise to perform, is costly, and requires 24-48 hr for a final result. It does provide specific and sensitive results for Clostridium difficile infection. While it served as a historical gold standard for diagnosing clinical significant disease caused by Clostridium difficile, it is recognized as less sensitive than PCR or toxigenic culture for detecting the organism in patients with diarrhea.
◦Enzyme immunoassay detects toxin A, toxin B, or both A and B. Due to concerns overtoxin A-negative, B-positive strains causing disease, most laboratories employ a toxin B-only or A and B assay. Because these are same-day assays that are relatively inexpensive and easy to perform, they are popular with clinical laboratories. However, there are increasing concerns about their relative insensitivity (less than tissue culture cytotoxicity and much less than PCR or toxigenic culture).
Source CDC: http://www.cdc.gov/HAI/organisms/cdiff/Cdiff_faqs_HCP.html


Crohnsforum Science Advisor
More Info (Still no help on Test Result Names):

-C. difficile toxin B, or toxins A and B, by enzyme immunoassay (EIA) tests are some of the most common tests used by laboratories. Results are typically available within 1 to 4 hours. Though these tests are rapid and widely available, they are not sensitive enough to detect many infections; they miss up to 30% of cases. Therefore, they are not recommended for use by some professional organizations.

-A glutamate dehydrogenase (GDH) test detects an antigen that is produced in high amounts by C. difficile, both toxin and non-toxin producing strains. It may be used as a first step to rule out an infection with C. difficile, but it should not be used alone. Since it is not very specific for toxin-producing C. difficile, it is often used in combination with a test for toxin by EIA or a cytotoxicity culture.

-Tissue culture to detect the C. difficile toxin is a test that looks for the effects of the cytotoxin on human cells grown in culture. It is a more sensitive method to detect toxin, but it requires 24 to 48 hours to get the test result.

-A relatively new molecular PCR (polymerase chain reaction) test can rapidly detect the C. difficile toxin B gene (tcdB) in a stool sample. This test is sensitive but is not widely available.

-Toxigenic stool culture, which requires growing the bacteria in a culture and detecting the presence of the toxins, is the most sensitive test for C. difficile, and it is still considered to be the gold standard. However, it can take 2 to 3 days for results. A culture will also not distinguish between C. difficile colonization and overgrowth/infection.

--Currently, there is no one test that is rapid, widely available, and sufficiently sensitive and specific. Until the development of such a test, the Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA) recommend a two-step testing process:

-Perform an initial screen on stool samples using a test for glutamate dehydrogenase (GDH). This test is considered to be very sensitive.

-Follow up positive screening results with a specific test for the toxin or the gene that codes for the toxin.
Source Labtestsonline: http://labtestsonline.org/understanding/analytes/cdiff/tab/test
One might think that our GI's would test us routinely for these things, C-diff, and while we are on the subject, keep a check on our vitamin and mineral levels.
Mine was diagnosed positive or negative. Of course my idiot insurance company only visually ID's c.diff initially (that's right, you read that correctly). If it isn't watery enough, they chuck the sample without testing it.

Of course this led me to spend New Years at the hospital with c.diff and pneumonia, but I digress. Can you tell I'm still bitter?:devil: