Diagnosis of C. Diff

Every nurse, new and seasoned, will tell you that you can diagnose C. diff by the noxious, pungent smell. While memorable, this is NOT the way to diagnosis a patient! If I could, I would emirate the odor across the inter webs, because truly, it is an unforgettable smell.  Below is the clinical way to diagnose C. diff.

Before you do any testing on your patient, there needs to be present a clinically significant amount of diarrhea or a pause in your GI motility (lack of peristalsis, medically known as ileus). There are diagnostic procedures that can be used to test for C. diff. One of which can be a endoscopic finding of "pseudomembranous colitis". Here is a video to exhibit what an endoscopy would look like and what this colitis is and looks like through a camera lens. 

What is the preferred method for diagnosis is lab testing of the diarrhea. Because the diarrhea is tested for a positive C. difficile toxin, which degrade at room temperature, it is critical that collected swabs are kept at 4 degrees Celsius after collection. The stool that is collected is used in a number of tests including:

• Polymerase chain reaction (PCR) : Detects Toxin A and B genes; tests are highly sensitive and specific. Results are quick, but because of the sensitivity of the tests, false positive results. This test is usually favored for initial diagnosis, while the doctors wait for secondary results that take longer to produce.
• Enzyme immuno assay (ELISA) for C. diff glutamate dehydrogenase (GHD): GDH antigen is an enzyme produced by all C. diff bacterial types. Unfortunately this enzyme is produced by all toxin producing and non-toxin producing C. diff. 
• ELISA for C. diff toxins A and B: Most C. diff strains produce both these toxins. Sensitivity is about 75%, but can be as specific as high as 99%. What this essentially means is that there is relatively high false negative unless a lot of the bacteria has been collected. This is inexpensive and results are within hours. 
• Cell culture cytotoxic assay: This is the gold standard. It is performed by adding a prepared stool sample to a petri dish with a layer of cells. If the C. diff toxin is present, the first layer if cells begins to change shape from a long stretched on cell to a round cell. This test is expensive and takes time.

Early diagnosis is key here in order to ensure patient safety of the individual diagnosed but other individuals on a hospital floor. Immediate isolation is required. In some cases, patients are put into isolation while results are pending. 

So remember, ALWAYS WASH YOUR HANDS.