Generally no, except for certain high-risk patients — and even then, not within 7 days of the initial test

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 repeat test during the next 14 days. The median time between the initial test and the first repeat test was 5 days. The proportion of patients with positive results on a subsequent PCR test was low (2.9% within 7 days after an initial negative test; 4.8% for days 8–14).

CITATION(S):

Khanna S et al. An evaluation of repeat stool testing for Clostridium difficile infection by polymerase chain reaction. J Clin Gastroenterol 2012 Nov/Dec; 46:846.