Tuberculin-(see purified protein derivative, PPD)		A sterile solution of products derived from cultures of Mycobacterium tuberculosis tubercle bacilli. These solutions are used in the tuberculin (PPD) skin test to determine whether a person has been infected with TB. Tuberculin does not contain any live or intact bacilli.
Tuberculosis (TB)		Disease caused by an organism in the Mycobacterium tuberculosis complex (usually M. tuberculosis or, less commonly, M. bovis or M. africanum).
TB meningitis		Inflammation of the meninges (membranes that surround the brain and the spinal cord) caused by TB infection that has spread to the central nervous system.
Tubercle		The characteristic pathologic lesion of tuberculosis: a small, round, grayish, translucent, granulomatous lesion, usually with central caseation and necrosis. It is made up of epithelioid macrophages surrounded by a layer of mononuclear cells, principally lymphocytes. Tubercles are found in the lungs in cases of pulmonary TB and in a variety of other organs in cases of extrapulmonary TB.
Tubercle Bacilli		Refers to Mycobacterium tuberculosis, discovered by Robert Koch in 1882.