C. diff is over diagnosed by popular molecular tests, study finds

Many patients are mistakenly diagnosed with Clostridium difficile infections and given unnecessary antibiotic treatments, according to a new study conducted by pathologists from UC Davis Health System in Sacramento, Calif.

Christopher R. Polage, MD, associate professor of pathology and infectious diseases at UC Davis Medical Center and the first author of the study, argues molecular tests may be the source of some incorrect diagnoses.

"It all depends on the type of test doctors use to diagnose patients," said Dr. Polage. "Molecular tests are great at detecting C. difficile DNA in the laboratory but probably over diagnose a lot of patients in hospitals, if doctors assume that everyone with a positive result needs treatment."

For UC Davis' two-year study, researchers examined more than 1,400 hospitalized patients who were tested for C. diff, tracking the outcomes and severity of their infections using the results of toxin tests versus molecular tests such as polymerase chain reaction tests.

The study revealed that many newer molecular tests — which nearly half of U.S. hospitals have adopted over the last six years — are unable to distinguish infected patients who need treatment from patients who are colonized with the bacteria and do fine without treatment.

Unfortunately, Dr. Polage notes, physicians frequently assume that all patients with positive molecular test results are infected and treat everyone with antibiotics.

"The more antibiotics we give, the more collateral damage we do to the microbiome, wiping out lots of beneficial bacteria that don't need to be treated," said Dr. Polage. "In addition, if we give antibiotics when they're not needed, we potentially perpetuate the cycle of C. diff spread and infection."

The study author suggests physicians and laboratories move toward defining C. diff infections by detecting toxins and limiting molecular tests to screening, similar to the U.K. and other countries in Europe.

 

 

More articles on infection control:
10 of the most interesting infection control developments this year
What are the best methods for cleaning and disinfecting hospital rooms?
25 things for healthcare CFOs to know about HAIs

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