Commercially available polyclonal antibodies raised against strains of mycobacteria were used to detect organisms in tissue sections from 34 cases of tuberculosis, leprosy, and atypical mycobacteria. Thirty-two cases of fungal infections, granulomatous inflammation, and sarcoidosis were used as negative controls. Sections stained with the use of antibodies raised against Bacillus Calmette-Guerin (BCG), Mycobacterium duvalii (MD), and Mycobacterium paratuberculosis (MP) were compared with Kinyoun and Fite-stained tissue sections. In caseating granulomata, clumps of mycobacterial debris, cells, and cell fragments stained. In histiocytic granulomata of mycobacterial infections, histiocyte cytoplasm contained both organisms and debris. The three antibodies showed cross-reactivity against the four groups of mycobacteria tested. Mycobacterial staining using immunoperoxidase was apparent in most cases at low-power (scanning) magnification. Thirty-two of 34 cases of mycobacterial infection, including all 24 Kinyoun-Fite-positive cases, were positive for immunoreactive organisms and debris using anti-MD, anti-BCG, and/or anti-MP. Eight of ten cases of culture-proven mycobacterial infection, in which Kinyoun and Fite stains were negative, had immunoreactive organisms or antigen with anti-BCG, MD, or MP. The antibodies also stained organisms in five cases of sporotrichosis in which the organisms were identified as yeast forms in tissue sections.

Sixty-four cases of deep fungal infections diagnosed using PAS or silver stains and 18 control cases of sarcoidosis, M. tuberculosis and M. leprae infection were stained using commercial polyclonal antibody raised against M. paratuberculosis (MP), M. Duvalii (MD), and Bacillus Calmette-Guerin (BCG). Nine of 13 cases of sporotrichosis stained positively using anti-MP antibody only; 13 of 14 cases of histoplasmosis stained with anti-BCG, anti-MD, and anti-MP; seven cases of cryptococcosis had only focal staining of rare individual organisms within masses of negative organisms; seven of eight cases of coccidioidomycosis stained predominantly with anti-BCG and anti-MP; eight cases of aspergillus had focal (1 to 5% of organisms) staining of hyphae with anti-BCG and anti-MD; and four of 12 cases of Candida infection showed focal nonspecific staining with both antibodies and nonimmune serum. Control cases of sarcoidosis exhibited no staining with any of the three antibodies, whereas cases of mycobacterial infection showed staining of bacilli and intracellular debris with all three antibodies.