The tuberculin test is a major diagnostic tool. A positive reaction to the tuberculin test indicates the presence of tuberculous infection, but the degree of activity, if any, or the severity of the disease process cannot be thus determined. There are also other limitations of the test as noted later in this discussion.
A routine tuberculin test should be performed sometime during the first year of life and annually or biennially thereafter. It is, of course, always indicated when there has been known contact with a tuberculous adult. In the latter instance, if the tuberculin reaction is negative, the test should be repeated eight to ten weeks after the removal of the contact. If the child remains in contact with a tuberculous adult, the tuberculin test should be repeated at three-month intervals.
Tuberculin solution, utilized in skin testing, is available in two forms, purified protein derivative (PPD) and old tuberculin (OT) solution.
PPD is the tuberculin solution now recommended because it is a more specific product. It is the protein of the tubercle bacillus obtained from filtrates of heat-killed cultures of tubercle bacilli that have been grown on a synthetic medium and then precipitated either by trichloracetic acid or neutral ammonium sulfate. The latter precipitant is used in the United States. The World Health Organization has designated one large batch of PPD (No. 49608, manufactured by Dr. Florence Seibert in 1939) as the international standard tuberculin (PPD-S).1 PPD is available commercially; it was formerly dispensed in tablet form and dissolved in a measured amount of diluent before use.
- Copyright © 1974 by the American Academy of Pediatrics