<s>[INST] How is TB diagnosed? [/INST] TB is diagnosed by demonstrating TB bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it.
Pulmonary TB is diagnosed through sputum smear microscopy and/or Chest X-Ray.
In Extra-pulmonary TB it is usually difficult to demonstrate TB bacteria, hence the diagnosis is made based on clinical suspicion and special tests depending on the organ affected. For instance, TB of the lymph nodes is diagnosed by a special test called FNAC (Fine Needle Aspiration Cytology).
In addition, NAAT (nucleic acid amplification test) is increasingly being used for diagnosing TB. They are highly accurate and rapid molecular tests. In addition to detecting TB, it also detects drug resistance to one of the potent anti-TB drugs, Rifampicin. Source: Government of India. Link: https://tbcindia.gov.in/index4.php?lang=1&level=0&linkid=382&lid=2751. Field: Lung Disease. Disease: Tuberculosis </s>