Cutaneous inflammation caused by inadvertent intradermal administration of DTP instead of PPD.

In 1979, 101 adults were skin-tested by a health department to evaluate tuberculin reactivity; of the 96 persons followed, 87 (91 per cent) experienced inflammation marked by swelling, erythema, arm pain, and fever. Five months later, a 5 mm to 10 mm purple macule persisted in 76 persons. The vials of PPD reportedly used for testing had been discarded, but PPD had been stored in the refrigerator with DT and DTP. The mean tetanus antitoxin titer in skin-tested persons was 0.14 units per ml (u/ml) vs 0.08 u/ml in untested control persons (p lesser than 0.03). The mean diphtheria antitoxin titer in skin-tested people was 0.90 u/ml vs 0.16 for controls (p = 10(-5)). The mean pertussis antibody in skin-tested persons was 1:169 vs 1:12 for controls (p = 10(-5)). Intradermal DTP in immune rabbits produced histologically typical Arthus reactions similar to those experienced by the humans. Seven months later, 90 persons received PPD injections. Ten had induration; none experienced persistent reactions. We concluded that the humans initially received DTP instead of PPD.