Multicenter clinical evaluation of the portrait toxigenic C. difficile assay for detection of toxigenic Clostridium difficile strains in clinical stool specimens

Blake W. Buchan, Tami Lea A. Mackey, Judy A. Daly, Garrison Alger, Gerald A. Denys, Lance R. Peterson, Sue C. Kehl, Nathan A. Ledeboer

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

We compared the Portrait Toxigenic C. difficile Assay, a new semiautomated sample-to-result molecular test, to a toxigenic bacterial culture/cell cytotoxin neutralization assay (TBC/CCNA) for the detection of toxigenic Clostridium difficile in 549 stool specimens. Stool specimens were also tested by one of three alternative FDA-cleared molecular tests for toxigenic C. difficile (Xpert C. difficile, Illumigene C. difficile, or GeneOhm Cdiff). The sensitivities and specificities of the molecular tests compared to TBC/CCNA were as follows: 98.2% and 92.8% for the Portrait assay, 100% and 91.7% for the Xpert assay, 93.3% and 95.1% for the Illumigene assay, and 97.4% and 98.5% for the GeneOhm assay, respectively. The majority of Portrait false-positive results (20/31; 64.5%) were also positive for C. difficile by an alternative molecular test, suggesting an increased sensitivity compared to the culture-based "gold standard" method. The Portrait test detected an assay input of 30 CFU in 100% of spiked samples and detected an input of 10 CFU in 96.7% of samples tested.

Original languageEnglish (US)
Pages (from-to)3932-3936
Number of pages5
JournalJournal of clinical microbiology
Volume50
Issue number12
DOIs
StatePublished - Dec 2012

ASJC Scopus subject areas

  • Microbiology (medical)

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