A nurse is caring for a patient with a suspected diagnosis of tuberculosis. The nurse should expect the physician to order which of the following tests to confirm this diagnosis?


•Positive sputum culture is the definitive diagnostic test for tuberculosis. 

•The presence of acid-fast-bacilli (AFB) on a sputum smear or other specimen is used to detect TB disease. Acid-fast microscopy is easy and quick, but does not confirm a diagnosis of TB because some acid-fast-bacilli are not M. tuberculosis.  Therefore, a culture is done on all initial samples to confirm the diagnosis.

•However, a positive culture is not necessary to begin or continue treatment for TB. In the presence of acid-fast-bacilli (AFB) on a sputum smear  and another diagnostic indications of TB infection (like a chest x-ray), treatment is often begun. 

•A skin test is used to screen people at high risk for TB. This is not a definitive diagnostic test and does not differentiate between active and latent TB, so a positive skin test needs to be confirmed with sputum culture.

•A posterior-anterior chest radiograph is used to detect chest abnormalities. Lesions may appear anywhere in the lungs. These abnormalities may suggest TB, but cannot be used to diagnose TB.

•Blood culture is not necessary for diagnosis of tuberculosis (unless suspecting disseminated tuberculosis).

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