Comparable Specificity of 2 Commercial Tuberculin Reagents in Persons at Low Risk for Tuberculous Infection

Abstract

The diagnosis of latent tuberculosis infection is the basis of preventive therapy and a key indicator of tuberculosis transmission. The tuberculin skin test, which is the intradermal injection of a purified protein derivative (PPD) from broth culture of Mycobacterium tuberculosis,¹ remains the only validated method for diagnosing latent tuberculosis. Parkdale Pharmaceuticals, Rochester, Mich (Aplisol), and Pasteur Mérieux Connaught USA, Swiftwater, Pa (Tubersol), are the 2 companies that manufacture tuberculin in the United States. Despite regulations for standardization of tuberculin manufacturing and testing, clusters of suspected false-positive results involving both products have been reported.^2-8 We performed a randomized, double-blind study of the 2 commercial reagents and PPD-S1 (the standard) in 2 populations: (1) persons at low risk for latent tuberculosis infection and (2) patients with culture-positive tuberculosis.