Обратная связьThe original tuberculin material used by Mantoux in his first studies of tuberculin reactions was a highly heterogeneous mix of substances from killed M. tuberculosis(9). This so-called old tuberculin was replaced in 1941 by a standardized preparation of PPD from M. tuberculosis. A single standard lot of this material was produced by Florence Seibert, termed “PPDS” (32); since then, all newly produced tuberculin material has been produced using the same methods and tested against this standard, measuring induration in sensitized guinea pigs. All commercially available tuberculin material, other than the “next generation” skin test described later, are manufactured to produce PPD material that is bioequivalent to this standard PPDS.
PPDS contains a mix of antigens, including some that are specific to M. tuberculosis, but also many that are found in nontuberculous mycobacteria and BCG. Hence, false positive reactions to PPDS have been described in people with nontuberculous mycobacterial disease or with sensitization to nontuberculous mycobacteria antigens (12), and in people who have received BCG vaccination, particularly if they received BCG more than once or after infancy (11).
Testing with PPDS is very safe. Although severe local reactions with blistering can be seen in 2–3% of people, these are true positive reactions that are self-limited and heal spontaneously. Allergic reactions, with generalized rash, occur in less than 1% of people (26), and anaphylaxis occurs in only 1 per million people (27). Based on decades of experience, TST with PPDS is considered safe in pregnant and lactating women (33).