Comparison of two Clostridium difficile toxin immunoassays and a real-time PCR assay for C. difficile tcdC to toxigenic culture for detection of toxin-producing C. difficile in clinical samples

• Main Author: Nana, Trusha
• Format: Others
• Language: en
• Published: 2014
• Subjects: Clostridium difficile > isolation & purification; Clostridium Infections > diagnosis
• Online Access: http://hdl.handle.net10539/13905

Background: Accurate diagnostic methods for Clostridium difficile infection (CDI) are required for optimal patient management, appropriate implementation of infection control measures and surveillance. An assay that also provides rapid results, is easy to implement in a routine diagnostic lab and is cost-effective would be ideal. Laboratory testing for Clostridium difficile infection is rapidly evolving. Recently published literature has shown that immunoassays for toxin detection, whilst being cheap and easy to implement, lack sensitivity. Molecular diagnostics that are sensitive and provide rapid results are now available. However, the high cost of these assays is of concern. As reflected in the literature the optimal test or testing algorithm for Clostridium difficile infection diagnosis is not clear. Objectives: This study aimed to compare the performance of a real-time PCR assay and two immunoassays, and to establish the optimal testing strategy for Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). Methods: Using toxigenic culture as the gold standard, the Roche PCR assay for the detection of the tcdC gene, the Immuno Card Toxins A & B immunoassay and the C. Diff Quik Chek Complete immunoassay were evaluated as stand alone assays and as part of testing algorithms. Results: The sensitivity, specificity, positive predictive value and negative predictive value of the various assays and algorithms ranged from 38% to 81%, 98% to 100%, 92% to 100% and 85% to 95%, respectively. The charge per sample tested varied widely depending on the assay and algorithm used. The maximum turnaround time ranged between four and twenty four hours. Conclusion: The algorithm combining glutamate dehydrogenase and toxin immunoassay testing of all samples followed by PCR testing of only a subset of samples, performed the best, providing accurate results rapidly and cost-effectively.