What is the most diagnostic test for tuberculosis?

The most diagnostic test for tuberculosis is the sputum for acid-fast bacilli. This test specifically involves collecting a sample of sputum (mucus from the lower airways) and examining it under a microscope to identify the presence of acid-fast bacilli, which are the bacteria responsible for tuberculosis, namely Mycobacterium tuberculosis. A positive result in this test indicates an active infection.

While a chest X-ray is valuable in detecting abnormalities in the lungs consistent with tuberculosis, it cannot definitively confirm the presence of the bacteria. Similarly, a complete blood count provides useful information about a patient's overall health but does not specifically identify tuberculosis. The skin test, known as the tuberculin skin test or Mantoux test, indicates exposure to the tuberculosis bacteria, but it cannot distinguish between latent infection and active disease. Therefore, sputum testing remains the gold standard for confirming an active tuberculosis infection.