Novel portable platform for molecular detection of toxigenic Clostridium difficile in faeces: a diagnostic accuracy study

Background: A novel portable platform for nucleic acid amplification enables rapid detection of diarrhoea causing toxigenic Clostridium difficile directly from faeces, even in resource-limited settings. We evaluated the accuracy and precision of the new commercial molecular test system. Methods: One thousand one hundred and sixty faecal samples from patients suspected of having Clostridium difficile infection (CDI) were analysed using the Orion GenRead C. difficile test system (Orion Diagnostica Oy, Espoo, Finland) and comparative methods in three teaching hospital laboratories in Finland and France. The precision of the Orion GenRead C. difficile test system was evaluated in a reproducibility study with a set of blind-coded samples. The test system is based on a new isothermal amplification technology (Strand Invasion Based Amplification, SIBA®) and detection of the tcdB gene of C. difficile. We calculated the sensitivity, specificity, and the overall agreement according to Clinical and Laboratory Standards Institute recommendations. Findings: The overall agreement of the Orion GenRead C. difficile test when compared to the comparative methods in routine use in the participating laboratories was between 96.7% and 98.8%. In the reproducibility study; the total percent agreement between three laboratories was 99.8%. Interpretation: The identification of toxigenic C. difficile from faeces with the light-weight portable Orion GenRead test system was highly sensitive and specific, and the results were reproducible in the participating laboratories. This platform could enable fast and accurate molecular pathogen detection even in resource-limited or point-of-care settings.