Today's Concept of the Tuberculin Test.
Abstract
T HE TUBERCULIN TEST IS THE MOST effective means for detecting tuberculous infection, and hence is an essential tool in ultimate eradication of the disease. In clinical practice it has been generally accepted that a positive tuberculin skin reaction indicates the possibility of tuberculosis, whereas a negative reaction, with few exceptions, rules out a tuberculous infection. Since the advent of isoniazid chemoprophylaxis, the tuberculin test has become essential for tuberculosis prevention by reason of its usefulness in revealing tuberculosis in the incipient stage, at which time administration of isoniazid may prevent the development of overt disease. Until recently, all positive tuberculin skin reactions have been attributed to infection by Mycobacterium tuberculosis. This view has been challenged lately with the increasing knowledge of other mycobacterial infections causing tuberculin cross sensitivity in man. This tuberculin cross reaction has posed a new problem in the interpretation of the tuberculin test. The purpose of this article is to bring up to date the interpretation of the tuberculin skin reaction in the light of present-day knowledge of tuberculosis and other mycobacterial infections based on studies in the Houston area, as well as on published works in current literature. The tuberculin patch test and the recently introduced Heaf and tine tests will be discussed in terms of their reliability and feasibility.