Comparative testing of skin reactions to PPD mycobacterins from Mycobacterium tuberculosis and Mycobacterium scrofulaceum in school-age children.

Comparative skin tests with 2 TU PPD-RT 23 with Tween 80 (prepared from M. tuberculosis) and 5 TU PPD-RS 95 with Tween 80 (prepared from M. scrofulaceum) were intradermally given to a total of 1,140 7-year-old children in two towns of Karviná district (340 and 255 children) and in Teplice (267 children) and Prague (278 children). In the two groups of Karviná district children the percentages of small-sized reactions (6-9 mm) to PPD-RT 23 were 13.6 and 22.3% compared to 7.1% in Teplice and 5.7% in Prague. The prevalence of small reactions to the PPD-RS 95 test in district of Karviná was 14.4 and 16.9%, in Teplice 4.5% and in Prague 6.8%. In the two towns of Karviná district the percentages of children whose reaction to PPD-RS 95 was larger than to PPD-RT 23 were 56.4 and 42.8%, in Teplice 24% and in Prague 24%. The hypothesis is advanced that the higher degree of skin hypersensitivity to the M. scrofulaceum mycobacterin which was found among the Karviná district children tested is due to sensitization with environmental mycobacteria which are common in this area.