Gross Reactions with Tuberculins on Guinea Pigs with Single and Double Experimental Infections with Mycobacteria. ∗

Summary

Primary sensitization of guinea pigs with Battey, fortuitum, human, photochromogen, and scotochromogen mycobacteria produced large tuberculin reactions to the homologous PPD's but less and varying degrees of cross reactivity with other PPD's. Double infections in guinea pigs from human and scotochoromogen bacilli gave large cross reactions with PPD-A and PPD-B, but not with PPD-Y or PPD-F. Double infections with human and photochromogen bacilli gave large reactions to PPD-S and PPD-Y but not to PPD-B or PPD-F. Double infections with Battey and human bacilli gave large cross reactions to PPD-scot. but not to PPD-Y or PPD-F. It is concluded from these observations that skin testing with a battery of PPD's at the 5 TU dose level may be a valuable diagnostic tool in the presence of infection by a single organism. This value decreases in the presence of a double infection.