Which two types of tests are used to detect TB bacteria in the body?

The TB skin test and the TB blood test are recognized as the primary methods for detecting Mycobacterium tuberculosis, the bacteria responsible for tuberculosis. The TB skin test, also known as the Mantoux test, involves injecting a small amount of purified protein derivative (PPD) intradermally and assessing the reaction after 48 to 72 hours. A significant induration can suggest exposure to the bacteria.

The TB blood test, or interferon-gamma release assay (IGRA), measures the immune response to specific TB antigens in the blood. This test does not require the patient to return for a reading, making it convenient in many cases. Both tests serve to identify whether a person has been infected with TB bacteria, even if they do not have active disease.

Other options do not describe appropriate methods for detecting TB. For instance, urine tests are generally not used for initial TB detection, and neither saliva tests nor X-rays provide conclusive information about TB infection. Thus, the TB skin test and the TB blood test are the established methods for diagnosis.