The clinical value of new diagnostic tools for tuberculosis

Barriers to global tuberculosis (TB) control include multidrug resistance, HIV infection, and weak health systems. Case detection is critical to TB control and is affected by all three of these. Currently, most low- and middle-income countries (LMICs) rely on direct sputum smear microscopy for diagnosis. Modern culture methods and molecular tests, previously considered too complex or too expensive for implementation in LMICs, are now being introduced there in parallel with a global effort to strengthen laboratories. It remains to be seen whether services based on these tools can be made widely accessible to patients. New point-of-care tests for TB are urgently needed but cannot be expected in the near future. In the meantime, diagnostic tools based on optimized smear microscopy, although less sensitive than reference laboratory tests, may be more accessible and have more impact on case finding. It is a matter of urgency that these improved microscopy services be integrated with services based on rapid methods that can identify multidrug-resistant cases.