What test is used to confirm a diagnosis of active pulmonary tuberculosis?

The diagnosis of active pulmonary tuberculosis is confirmed primarily through a sputum culture for acid-fast bacillus. This test involves collecting a sample of sputum (mucus that is coughed up from the lungs) and then culturing it to check for the presence of Mycobacterium tuberculosis, the bacteria responsible for tuberculosis.

Sputum cultures are highly specific and can provide definitive evidence of an active infection, which is crucial for initiating appropriate treatment. The culture process allows for not only the identification of the bacteria but can also determine its sensitivity to various medications, guiding effective treatment plans.

Other tests, like the tuberculin test or Mantoux test, are useful for screening and identifying potential latent tuberculosis infections but do not confirm active disease. Chest x-rays may indicate signs consistent with active pulmonary tuberculosis, such as cavitary lesions or infiltrates, but cannot definitively confirm the presence of the bacteria. The enzyme-linked immunoassay (ELISA) test is utilized primarily for detecting antibodies and is not specific for diagnosing active pulmonary tuberculosis. Therefore, the sputum culture remains the gold standard for confirming an active infection.