Both the rate and severity of C. Difficile infection have risen in recent years as accurate diagnoses have become harder to make, according to a new study.

A number of misconceptions exist when it comes to diagnosing C. Difficile, according to researchers at Northwestern University in Illinois. One such belief is that C. Difficile can be present if a patient has fewer than three loose stools per day, which study authors debunk in their report. Authors also point out that the glutamate dehydrogenase test, which is commonly used in diagnosing C. Difficile infection, is not sensitive enough to be accurate for initial testing. Additionally, repeating such insensitive tests is not useful, they say. Nursing homes are constantly on guard against C. Difficile outbreaks.

To more accurately diagnose a C. Difficile infection, clinicians should use tests that measure levels of toxin B in the stool or pseudomembranes in the colon, researchers say. Different methods should be used if multiple tests are required. The report appears in the August 4 issue of The Annals of Internal Medicine.