COMMENTARY

C difficile: Guidelines to Diagnose, Treat, and Prevent

David A. Johnson, MD

Disclosures

May 31, 2013

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In This Article

Hello. I'm Dr. David Johnson, Professor of Medicine and Chief of Gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia.

Clostridium difficile has emerged as the leading nosocomial infection and cause of death in the United States. It affects hospitalized patients as well as outpatients. The economic burden of this disease in the past year is estimated to be $3.2 billion. It is very timely that the American College of Gastroenterology, led by Dr. Christina Surawicz, recently published guidelines[1] for the diagnosis and management of C difficile infections. I wanted to put some perspective on this and give you what I thought were the highlights.

Testing and Diagnosis

C difficile is not an uncommon bacterial colonization. It is estimated to colonize 5%-15% of healthy adults and may be in excess of 80% in neonates and newborns. In the long-term care population, it is estimated to be 50%-60% of patients. Again, this is not pathogenic in all cases. The American College of Gastroenterology says that we should be testing for C difficile only in people with diarrhea, and that is a very important point. If somebody has an ileus or another reason to prevent them from excreting, then perhaps a rectal swab may be helpful, but we're not really looking for C difficile in nondiarrheal patients. That is an important starting point. Another point is to not document cure of these patients after treatment if the diarrhea goes away. I see this frequently when someone has been treated and it is documented that the organism has been eradicated, when in fact it may be a commensal organism in the patient without diarrhea.

Let's talk about diagnosis. Over the past decade or so, diagnosis has been driven by testing for toxins A and B and by ELISA (enzyme-linked immunosorbent assay). These are tests that recognizably do not have quite the sensitization that we need. The sensitivity and specificity have been upped by the introduction of 2 tests. One is the glutamate dehydrogenase (GDH) test, which is done on feces. This test is very sensitive but not as specific as we would like it to be. However, the GDH test is important because GDH is very highly produced by C difficile, not only the toxic type but also the nontoxic type. Hence, its specificity may not be implicit that this is active disease. It is emerging as the go-to first test for patients when we are trying to definitively analyze them for C difficile.

The second test is a nucleic acid amplification test. This test is also done on feces, but it is a highly sensitive and very specific test. If your hospital allows you to go straight to this test, that is certainly a strategy that could not be argued. But from a cost perspective, most hospitals are looking at a 2-step or 3-step algorithm. Patients are treated initially and evaluated with the GDH test. If it's positive, they do the ELISA test. If the ELISA is discordant from the GDH test, then they take a third step, which is the nucleic acid amplification test. It could be argued that you could skip the ELISA and go straight to the nucleic acid amplification test. That is a matter of cost and it is left to your best discretion. You should be looking at this in your hospital if you're not currently doing so.

One recommendation that I thought was very sanguine is that repeat testing for C difficile after one negative test is not recommended. I see patients who are in bacterial isolation and all their family members are dressed like lemons, sitting in the rooms wearing isolation garb. But if it's negative, you have less than a 5% chance, even on ELISA testing, to have a positive. If you ramp up your sensitivity of detection with this GDH test followed by either the ELISA or the nucleic acid amplification test, one test should be sufficient. And that's the end of the game.

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