Impact of ribotype on Clostridioides difficile diagnostics

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Diagnostic Science

Background:

• Clostridioides difficile infection (CDI) diagnosis relies on various methods with differing performance.
• PCR ribotyping is crucial for understanding C. difficile epidemiology and virulence.
• Evaluating diagnostic accuracy requires considering the impact of prevalent C. difficile strains.

Purpose of the Study:

• To assess the performance of different diagnostic methods for CDI in Sweden.
• To investigate how PCR ribotype influences the sensitivity and specificity of these diagnostic tests.
• To provide insights into optimizing CDI diagnostics based on local C. difficile strain characteristics.

Main Methods:

• Retrospective analysis of 17,878 stool samples tested between 2011-2016 across 26 laboratories.
• Comparison of enzyme immunoassays (EIAs), cell cytotoxicity neutralization assay (CTA), and nucleic acid amplification tests (NAATs).
• PCR ribotyping of C. difficile isolates to determine toxigenicity and strain type, correlating with diagnostic test results.

Main Results:

• Nucleic acid amplification tests (NAATs) and membrane-bound EIAs demonstrated the highest overall sensitivity and specificity.
• Significant variation in diagnostic sensitivity was observed across different PCR ribotypes, ranging from 33% to 100%.
• Methods showed 100% sensitivity for ribotypes 027 and 013, but lower sensitivity for prevalent types like 014, 020, and 001 (38-100%).

Conclusions:

• The performance of CDI diagnostic tests is significantly influenced by the distribution of C. difficile PCR ribotypes.
• Diagnostic test evaluations may be overestimated in settings with a high prevalence of specific ribotypes, such as ribotype 027.
• Accurate CDI diagnosis necessitates considering both the chosen method and the circulating C. difficile strain types.