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

Area of Science:

• Microbiology
• Molecular Diagnostics
• Infectious Diseases

Background:

• Clostridium difficile is an increasingly identified pathogen in both hospital and community settings.
• The organism possesses a variable pathogenicity locus (PaLoc) encoding toxins A and B.
• Existing diagnostic methods have limitations in cost, sensitivity, or specificity.

Purpose of the Study:

• To develop a rapid, sensitive, and specific diagnostic test for toxigenic C. difficile.
• To combine the cost-effectiveness of immunoassays with the accuracy of DNA amplification.
• To target a genetically stable region within the C. difficile PaLoc.

Main Methods:

• A hot-start isothermal DNA amplification method was developed targeting the tcdB gene sequence.
• Detection was achieved using a multiplexed chip-based hybridization capture readout.
• The assay was automated on an electromechanical instrument for fecal sample analysis.

Main Results:

• The manual assay detected toxigenic C. difficile with high sensitivity and specificity within 1 hour.
• Automated assay demonstrated analytical sensitivity of 10 CFU/sample for C. difficile.
• Testing of 130 patient samples showed 97% sensitivity and 100% specificity.
• The assay successfully discriminated against other enteric bacteria.

Conclusions:

• The developed assay offers a rapid and accurate method for detecting toxigenic C. difficile.
• Automation enhances analytical sensitivity and specificity for clinical sample analysis.
• Further large-scale clinical studies are planned to validate clinical performance.