Methods to Improve Confidence in the Accuracy of Molecular Testing for Multidrug-Resistant Tuberculosis

Area of Science:

• Molecular Diagnostics
• Microbiology
• Public Health

Background:

• Accurate diagnosis of tuberculosis (TB) and multidrug-resistant TB (MDR-TB) relies on molecular tests detecting Mycobacterium tuberculosis DNA.
• Quality assessment of these tests requires reference measurement procedures (RMPs) and material standards, which are currently lacking.
• These standards are crucial for characterizing drug resistance and mixed bacterial populations in clinical samples.

Purpose of the Study:

• To establish and validate digital PCR (dPCR) as a reference measurement procedure (RMP) for multidrug-resistant tuberculosis (MDR-TB) material standards.
• To assess the performance of existing molecular diagnostic tests for TB and MDR-TB using these newly characterized standards.

Main Methods:

• Four material standards were prepared and characterized using dPCR to quantify drug-resistant and -susceptible genotypes.
• An interlaboratory study involving 9 laboratories across Africa and Europe evaluated 3 MDR-TB and 2 TB-only detection methods.

Main Results:

• All molecular tests accurately identified M. tuberculosis.
• Two out of three MDR-TB tests correctly identified drug resistance, with discrepancies noted in samples with low concentrations or mixed genotypes.
• The developed dPCR-based RMPs and material standards provide a robust method for quality assessment.

Conclusions:

• The dPCR-based approach enhances quality assessment for MDR-TB testing, improving accuracy and reliability.
• This can guide test development, selection, and regulation, leading to more confident clinical decisions.
• Improved MDR-TB testing can lead to better patient treatment guidance and outcomes.