TB Diagnostic Tests

Sputum smear microscopy remains the primary diagnostic method for more than half of the TB-affected population in high-burden countries despite newer molecular options. Since 2011, rapid molecular tests have transformed TB diagnosis by replacing traditional dependence on microscopy and culture in many settings. TB disease confirmation uses a microbiological reference standard: positive culture using the mycobacteria growth indicator tube (MGIT). Pooled sputum testing combines sputum samples from multiple individuals and tests them together using Xpert Ultra, usually in pools of four. WHO recommends newer molecular tests as effective, rapid, and reliable, but their high cost limits widespread use. Five approaches are evaluated for each participant: capillary blood CRP testing, individual Xpert MTB/RIF Ultra, pooled Xpert Ultra, lateral-flow urine LF-LAM, and digital chest X-ray with AI computer-aided detection.