If tests for C. difficile and C. difficile toxin are positive, it is likely that the person’s diarrhea and related symptoms are due to the presence of toxin-producing C. difficile.
A positive result for C. difficile bacteria or C. difficile antigen but a negative C. difficile toxin result means that the bacteria are present in the digestive tract but are not producing a detectable level of toxin.
Negative test results for both the bacteria and the toxin may mean that the diarrhea and other symptoms are being caused by something other than C. difficile.
Since the toxin breaks down at room temperature within two hours, a negative result may also indicate that the sample was not transported, stored, or processed promptly.
If there is a concern that a stool specimen has not been collected and processed properly, a second specimen may be submitted for testing after discussion with the laboratory.