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J Clin Microbiol. 2012 Aug;50(8):2681-7. doi: 10.1128/JCM.00621-12. Epub 2012 Jun 6.

Automated detection of toxigenic Clostridium difficile in clinical samples: isothermal tcdB amplification coupled to array-based detection.

Author information

1
Great Basin Scientific, Salt Lake City, Utah, USA. bhicke@gbscience.com

Abstract

Clostridium difficile can carry a genetically variable pathogenicity locus (PaLoc), which encodes clostridial toxins A and B. In hospitals and in the community at large, this organism is increasingly identified as a pathogen. To develop a diagnostic test that combines the strengths of immunoassays (cost) and DNA amplification assays (sensitivity/specificity), we targeted a genetically stable PaLoc region, amplifying tcdB sequences and detecting them by hybridization capture. The assay employs a hot-start isothermal method coupled to a multiplexed chip-based readout, creating a manual assay that detects toxigenic C. difficile with high sensitivity and specificity within 1 h. Assay automation on an electromechanical instrument produced an analytical sensitivity of 10 CFU (95% probability of detection) of C. difficile in fecal samples, along with discrimination against other enteric bacteria. To verify automated assay function, 130 patient samples were tested: 31/32 positive samples (97% sensitive; 95% confidence interval [CI], 82 to 99%) and 98/98 negative samples (100% specific; 95% CI, 95 to 100%) were scored correctly. Large-scale clinical studies are now planned to determine clinical sensitivity and specificity.

PMID:
22675134
PMCID:
PMC3421499
DOI:
10.1128/JCM.00621-12
[Indexed for MEDLINE]
Free PMC Article
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