Unnecessary repeat Clostridium difficile PCR testing in hospitalized adults with C. difficile-negative diarrhea.

The aim of this study was to determine the extent and associated costs of repeat Clostridium difficile stool polymerase chain reaction (PCR) assays in patients with initially negative PCRs. C. difficile stool PCRs were done on adult hospitalized patients with diarrhea. The number/time course of repeat PCRs on initially negative PCR patients was determined. Of 5,027 C. difficile stool PCRs, 814 (16.2 %) were positive and 4,213 (83.8 %) were negative. Ninety-seven of the initially PCR-negative patients had >2 repeat tests 1-59 days after the initial negative stool PCR. Repeat negative PCR testing rarely resulted in a subsequent positive result (0.05 %). The unnecessary costs of 97 repeat PCRs was $32,658.00. Many of these patients were originally given empiric oral anti-C. difficile therapy, in spite of repeatedly negative PCRs.