[Infectious Disease Reports 2011; 3:e5] [page 15] Diagnosis of Clostridium difficile infection: comparisonof four methods on specimenscollected in Cary-Blair trans-port medium and tcdB PCR on fresh versus frozen samples

Clostridium difficile infection (CDI) caused by toxigenic strains of C. difficile is primarily a nosocomial infection with increasing preva-lence. Stool specimens are typically collected in Cary-Blair transport medium to maximize cul-ture-based detection of common stool pathogens. The goal of this study was to estab-lish an analytically accurate and efficient algo-rithm for the detection of CDI in our patient pop-ulation using samples collected in Cary-Blair transport medium. In addition, we wished to determine whether the sensitivity and specifici-ty of PCR was affected by freezing samples before testing. Using 357 specimens, we com-pared four methods: enzyme immunoassay for the antigen glutamate dehydrogenas