Skin testing: a comparison of the jet injector with the Mantoux method

Employees in a large industry in Baltimore were tested with 5 TU of purified protein derivative (PPD)-S and PPD-B using both jet injector and Mantoux methods. Wheal sizes tended to be larger among men than women and larger among blacks than whites, regardless of the technique used. Within any given race-sex group, and also within subjects, considerable systematic and nonsystematic variations in wheal size occurred when the jet injector was used. On the contrary, there was little variation in wheal size within race-sex groups when the Mantoux method was used. Mean wheal sizes elicited with the jet injector tended to be smaller than those elicited with the Mantoux method. There were also considerable differences in the reactions elicited by the 2 techniques. The Mantoux method elicited more and larger reactions than the jet injector, which suggests that the 2 injections are in some way qualitatively or quantitatively different. For jet injector tests, the frequency of reactions of different size tended to be related to the size of the wheal measured immediately after injection. This was not true for the Mantoux method. On the basis of these findings, it is suggested that the jet injector method is inferior to the Mantoux method in tuberculin skin testing.