Tuberculosis skin testing and preventive therapy.

Tuberculin skin testing is a reliable tool for the detection of tuberculous infection and the eventual prevention of tuberculous disease. False-negative tests may occur in individuals with a compromised immune system, including those with human immunodeficiency virus (HIV) infection, persons taking immunosuppressive drugs (eg. corticosteroids), the severely malnourished, and the elderly. Nevertheless, it still is useful in detecting infection in those persons who are in close contact with patients with tuberculous disease, including family members, hospital personnel, and those from high risk areas. Once a skin test is found to be reactive, further diagnostic studies should be done to rule out tuberculous disease. Once ruled out, preventive therapy with isoniazid should be instituted. Suitable candidates for prophylaxis include all individuals with reactive tuberculin skin tests who are (1) household contacts of patients with tuberculous disease, (2) recent tuberculin test convertors, (3) individuals with prior tuberculosis (TB) who did not receive adequate chemotherapy, (4) all individuals under the age of 35, and (5) individuals in special clinical circumstances who are over the age of 35. Newer, shorter course regimens are currently being studied. TB cannot be eliminated until the importance of preventive therapy is recognized by all.