November 11th, 2012

C. difficile: How many stool samples do you send for a diagnosis?

The diagnosis of this increasing and now epidemic infection has been evolving as well. When I first started testing for this infection, a cytotoxin assay was used that delayed the diagnosis and was very operator-dependent. Enzyme immunoassays came next, and more recently PCR testing of stool has become available. Despite the increased accuracy and more rapid results available today with PCR testing, it seems that we have not yet altered our testing pattern. It used to be that we recommended 3 separate stool samples be tested before excluding the diagnosis of C. diff infection. I know that practice remains prevalent today.

So, what I would like to find out from you are the following…

1) Do you know what C. diff test is used where you practice?

2) How quickly do you get the results back?

3) How many stool samples do you routinely test?

4) If testing is negative and symptoms persist, how long do you wait before “retesting?”

Looking forward to the dialogue.

3 Responses to “C. difficile: How many stool samples do you send for a diagnosis?”

  1. 1. PCR is the only test we use
    2. Lab processes daily at noon. Results in several hours.
    3. Single sample used, must not be formed / must take the shape of the container, no repeat test within 60 days if positive
    4. Not included in protocol

  2. RSIN says:

    1) we get initial GDH positivity result followed by cytotoxicity by culture
    2. GDH usually in hours, culture 3-4 days
    3. 1 sample,
    4. if negative I repeat based on symptoms in 48-72 hours

  3. hhc says:

    1. pcr
    2. a few hours
    3. 1
    4. depends on pt. if sx worsen after a few days, will retest. may even treat empirically in right clinical picture.

Gastroenterology Research: Author M. Brian Fennerty, M.D.

M. Brian Fennerty, MD


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