Comparison of Sensitivities to Two Commercially Available Tuberculin Skin Test Reagents in Persons with Recent Tuberculosis

Discrepancies have been reported between results obtained with tuberculin skin tests (TSTs) performed with use of different reagents. We compared TST results and determined the sensitivities of the two commercially available TSTs in 51 human immunodeficiency virus-negative persons with culture-confirmed active tuberculosis. Simultaneous TSTs were done with use of the Mantoux method and 5-tuberculin unit purified protein derivative (PPD) tuberculin preparations from single lots of Aplisol and Tubersol. Aplisol skin test reactions ranged from 5 mm to 26 mm (median, 16.0 mm), and Tubersol reactions ranged from 7 mm to 23 mm (median, 15.0 mm). The mean difference in paired reaction sizes for the two reagents was 0.58 mm and was not statistically different from zero (P value, 0.26). The difference in reaction sizes was < or =2 mm in 55% and > or =5 mm in 18% of patients. With a cutoff of either 5 mm or 10 mm to define a positive reaction, all results were concordant, with sensitivity of 100% and 96%, respectively. We found indistinguishable reaction size distributions and median TST results for the two commercially available PPD TST reagents, Aplisol and Tubersol, in a population with recent culture-proven tuberculosis.