Clostridium difficile Toxin Detection by PCR

On December 14, 2009, rapid PCR testing for the detection of toxin producing strains of Clostridium difficile will replace the enzyme immunoassay currently performed in the Clinical Microbiology Laboratory. Specimens submitted to the Clinical Microbiology Laboratory 0700-2100 will have results reported within 2 hours.

C. difficile toxin PCR may be ordered under the "Microbiology: Stool/GI aspirate" test request (EPIC order LAB5842) by selecting "stool" as the specimen source and "C. difficile toxin PCR" from the bacteriology test menu.

Collection & Transport: Collect unformed stool specimens in a clean container. If transport is delayed, store specimen at 2 - 8 °C (stable for up to 5 days). Alternatively, specimens can be kept at room temperature (20 - 30 °C) for up to 24 hours.

The number of C. difficile toxin PCR test requests for a patient will be limited to two per week. The higher sensitivity of PCR in comparison to cell cytotoxicity and immunoassay methods supports this policy [Ann Intern Med 2009; 151:176]. Since C. difficile colonization rather than infection may exist, only unformed stool specimens from patients with signs and symptoms of C. difficile infection should be tested. Once a patient is diagnosed with C. difficile infection, therapeutic response should be based on clinical signs and symptoms; a "test of cure" should not be done since patients may remain colonized with toxin-producing strains following recovery.

Questions may be directed to Dr. Sandra Richter (6-2990) or Dr. Daniel Diekema (4-5626).