Does a Negative C. difficile PCR Need to Be Repeated?

The recent increase in incidence and severity of Clostridium difficile infection has prompted a progressive switch from enzyme immunoassays (EIAs) to polymerase chain reaction (PCR) assays, because the latter is more sensitive and therefore more reliable when negative. But what about patients with suspected C. difficile infection whose symptoms persist despite negative PCR results? In a recent retrospective study, researchers at the Mayo Clinic evaluated the utility of repeat PCR testing for such patients. All testing was done using a real-time PCR assay developed in the Mayo Clinic's microbiology laboratory.

Of the 15,515 patients who had an initial PCR test for C. difficile between January 1, 2008, and June 30, 2010, 12.7% had at least one…