Tuberculin skin test. A diagnostic aid for finding M. tuberculosis infection. A small dose of tuberculin (see also Mantoux method and PPD) is injected just beneath the surface of the skin by the Mantoux method, and the area is examined for induration by palpation 48--72 hours after the injection. Indurated margins should be read transverse (perpendicular) to the long axis of the forearm.
Tuberculin Skin Test. A purified protein derivative (PPD) of the tubercle bacilli, called tuberculin, is introduced into the skin by scratch, puncture, or intradermal injection. If a raised, red, or hard zone forms around the test site, the person is said to be sensitive to tuberculin, and the test is read as positive.