Diagnostic tests: Testing for tuberculosis

Summary Tuberculosis is caused by Mycobacterium tuberculosis. The approach to testing for tuberculosis depends on whether the aim is to diagnose active disease or latent infection. if active disease is suspected, it is important to identify the site of disease. Analysis of sputum specimens for mycobacteria should precede other tests. An infection should never be diagnosed as latent until active disease has been excluded. Tuberculin skin testing is recommended for diagnosing latent infection, but interferon gamma release assays may be useful in some circumstances.