C-Dif

[EJSRN, BSN, RN]

anyone know the difference between C-Dif antigen and toxin? Do both require isolation? Thank you!:nuke:

[icyounurse, BSN, RN]

I looked this up just because I was curious. It looks like when you test for a C diff antigen it means it is positive for C-diff but not for a specific strand. You have to test for different types of toxins (toxin assay) to get the specific strand I believe, they can be toxigenic or non-toxigenic. So a positive test for C diff toxin or antigen would be positive for infection and both would be placed in isolation.

"C. DIFF CHEK™ detects a protein that is produced in large amounts by all strains of Clostridium difficile. This "common antigen" is the enzyme, glutamate dehydrogenase. Almost all species of bacteria produce glutamate dehydrogenase enzymes so the trick is to detect the specific C. difficile enzyme by using monoclonal antibodies (some other tests for the "common antigen" use antibodies that cross react with the enzyme from other species). Our test is extremely specific and very sensitive - it detects the presence of even relatively small numbers of cells of either toxigenic or non-toxigenic strains of C. difficile in feces. In most hospitals about 80% of the C. difficile strains produce toxins and a single patient may have multiple strains. This test is especially useful when tissue culture is used as the toxin detection assay. By use of the C. DIFF CHEK™ the feces that do not contain C. difficile are reported as negatives in about an hour and this reduces the number of samples that need to be tested with the more time-consuming tissue culture assay by about 70%. The test also raises a caution flag for those patients that have organisms present but no toxin - the C. DIFF CHEK™ can detect the presence of organisms before there are enough cells present to produce detectable toxin."

from http://www.techlab.com/product_details/t5025.htm

Hope this helps,

Susannah

[EJSRN, BSN, RN]

Thank you! So it takes time for the toxins to build and if it was a newly acquired infection they wouldnt show up yet and the antigens are already positive. I think I understand. But we can agree that both require isolation then!

[core0]

Thank you! So it takes time for the toxins to build and if it was a newly acquired infection they wouldnt show up yet and the antigens are already positive. I think I understand. But we can agree that both require isolation then!

Not quite. A substantial portion of patients will be colonized with asymptomatic C-diff. This only becomes a problem if the other bacterial flora becomes suppressed allowing the C-diff to flourish. This then produces a toxin that makes the patient sick.

The antigen test detects whether there is C-diff or not. It will be positive in both asymptomatic and symptomatic patients. If it is negative you can rule out C-diff. If it is positive you cannot conclude that they have C-diff. The advantage is that the test can be done very quickly and is relatively cheap.

The C-diff toxin test requires growth of the C-diff in a tissue culture and the detection of the toxin. This is diagnostic for symptomatic C-diff. It directly measures how much toxin is produced.

Many academic centers use a two step method where they test for the C-diff antigen then test the positives for the Toxin. So in this case only the Toxin positive patients should be on isolation (although since many of the antigen positive patients will be toxin positive you could put them on until the toxin comes back). The Yale lab test is shown here for an example:

http://web.med.yale.edu/labmed/virology/newsletters/Newsletter16_3.pdf

Just to make things more confusing there are now tests for the toxin antigen. This tests directly for the toxin using a test similar to the C-diff antigen test. This test is more specific than the c-diff antigen test. It is more expensive than the two step method above but does not require a virology lab like the toxin cultures. If this is positive the patient has C-diff.

So your answer depends on what test is being done, but generally it would be safer to to put patients on isolation until its confirmed.

David Carpenter, PA-C

[EJSRN, BSN, RN]

only the pts positive for the c-dif toxin will be in isolation. If they are positive for the antigen, but negative for the toxin the do not have to be on isolation. Do i have it right now? thanks!

[loricatus]

Although the previous poster is on target, I would just like to add something about immunology that could clarify things better.

An antigen is just another name for a substance that elicits an immune response in the body to make antibodies to attack the antigen. It usually is just a certain piece of the surface of the substance, where the antibody can form a lock and key type of attack. So you could thinK of the C-Diff antigen as having an overgrowth of C-Diff itself.

The toxin comes as a byproduct of the bacteria's metabolism. So, you need to have a substantial overgrowth of the bacteria for the toxins to be detectable.

All of us have c-diff in our intestines. It is only when the other bacteria we have that control it's growth are destroyed (antibiotic therapy), can it overgrow and cause an immune response (antibodies to attack the antigens) and toxins.

[EJSRN, BSN, RN]

so positive for antigen does require isolation????????????????

[core0]

so positive for antigen does require isolation????????????????

Positive for c-diff antigen does not require isolation. Positive for C-diff toxin requires isolation. Positive for c-diff toxin antigen requires isolation. Per our policy C-diff antigen is isolated until the toxin come back since 2/3 will be toxin positive. It kind of depends on your local prevalence. What does your policy say?

David Carpenter, PA-C

[gill1razor]

My 1 yr. old tested positive for both toxin A and B, but was never put into isolation. Should I be worried about that? If anyone has info, please send it!!!