The PPD test is also known as the tuberculin test, and a positive PPD test indicates either a Mycobacterium tuberculosis infection or BCG vaccination, although it is impossible to determine which is the cause. Currently, the most important test to determine if you have been infected with Mycobacterium tuberculosis is the T-SPOT test. A positive T-SPOT test indicates that you have been infected with Mycobacterium tuberculosis, and a negative T-SPOT test indicates that you are not infected with Mycobacterium tuberculosis. It is more accurate than the PPD test. The tuberculin test mainly reflects the presence or absence of BCG vaccination or is used as a screening test for the population. People with a negative PPD test need to get BCG vaccination, while those with a positive PPD test do not.