TB-CAPT MTB/XDR Study

Two-site Laboratory-based Diagnostic Accuracy and Feasibility Study of the Xpert MTB/XDR Assay for Detection of Isoniazid, Fluoroquinolone, Ethionamide and Second-line Injectable Anti-tuberculosis Drug Resistance

The Cepheid Xpert MTB/XDR cartridge, which runs on the same platform as Xpert MTB/RIF Ultra, has been developed to detect additional resistance to isoniazid, fluoroquinolones and second-line injectable anti-tuberculosis drugs and provides results within 2 hours and on primary samples. An evaluation of the the Xpert MTB/XDR assay is currently underway in clinical settings in South Africa, India and Moldova. The TB-CAPT MTB/XDR Study will add further diagnostic accuracy and feasibility data to the evidence base for the Xpert MTB/XDR assay.

Inclusion Criteria:

• Mtb-positive, rifampicin-resistant respiratory specimen identified on Xpert MTB/RIF Ultra

Exclusion Criteria:

• Residual SR-sputum mix not retained or not found
• Patient previously included in the study

Exclusion for diagnostic accuracy and time-to-result endpoints:

• Insufficient residual SR-sputum mix remaining for Xpert MTB/XDR (<2 ml)

• Xpert MTB/XDR unsuccessful

• No second / follow-up specimen received

• Second / follow-up specimen culture-negative, contaminated or not available

• Reference standard uninterpretable (phenotyping or WGS)

  • Where phenotypic susceptibility testing results are uninterpretable, specimens will still be included in WGS comparison
  • Where WGS results are uninterpretable, specimens will still be included in phenotypic susceptibility testing comparison