Serological reactions to Nocardia antigens.

Sera from 23 patients with nocardiosis were tested for the presence of precipitating antibodies against an extract of Nocardia asteroides. Sera from nine of 20 patients infected with Nocardia asteroides and one of three sera from patients with Nocardia brasiliensis produced one to three precipitin lines with the antigen. Sera from eight of 55 patients with tuberculosis and 11 of 13 patients with leprosy also contained Nocardia precipitins. None of 33 sera from patients with cryptococcosis, blastomycosis, actinomycosis, histoplasmosis, coccidioidomycosis, mucormycosis or candidiasis contained Norcardia antibodies. None of the sera from ten patients infected with Staphylococcus aureus, ten patients infected with Pseudomonas, or 16 sera from uninfected patients contained Nocardia precipitins.