There are two kinds of tests that are used to detect TB bacteria in the body: the TB skin test (TST) and TB blood tests.  A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has  infection (LTBI) or has progressed to tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease