Reserve testing for patients with 3 or more unformed stools in 1 or more days.
Negative predictive value is greater than 97%.
Positive tests occur in patients colonized by C. difficile without colitis. Reserve treatment for those with clinical colitis.
Test not validated for patients less than 2 years of age. Specificity is lowest in children under the age of 2 years. Interpret tests on those under two with caution.
C. difficile positive patients should be placed in enhanced contact precautions for the duration of hospitalization.
The C. difficile epidemic strain, described here as NAP1, is toxinotype III and has been associated with worse disease severity, i.e., it is hypervirulent. The epidemic strain of C. difficile is REA (restriction endonuclease) group BI, pulse field gel electrophoresis (PFGE) type NAP1, and PCR robitype 027. The strain also contains an 18 bp tcdC deletion and produces binary toxin. The assay used to test this specimen detects the tcdC deletion and the binary toxin. Because the assay does not use REA, PFGE or PCR ribotyping for detection of 027/NAP1/BI, results are considered presumptive.
Non-027/NAP1/BI isolates representing toxinotype XIV and occasionally toxinotypes IV, V and X may be reported as NAP1 positive using this assay.