LPA for DR-TB Diagnosis

As per the Integrated Drug Resistant Tuberculosis (DR-TB) Diagnostic Algorithm:

• Nucleic Acid Amplification Test (NAAT) are preferred for initial detection of Rifampicin (R) resistance.
• Line Probe Assay (LPA) test is preferred for detection of Isoniazid (H), Fluroquinolones (FQ) and second-line injectable (SLI) drugs resistance.
  • When Rifampicin resistance is detected by NAAT (Figure):
    • Offer first-line (FL) and second line (SL) LPA
    • Direct LPA performed on smear positive specimen or indirect LPA is performed on culture isolate when smear is negative
  • When Rifampicin resistance is not detected by NAAT (Figure):
    • Offer FL-LPA to detect H resistance
    • Direct LPA performed on smear positive specimen or indirect LPA is performed on culture isolate when smear is negative
    • If H resistance is detected, SL-LPA is performed to check FQ resistance.

Figure: Flow Chart to decide FL/SL-LPA after NAAT Results

Resources

• Guidelines for PMDT in India, 2021.​
• GLI LPA Guidance Document.

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