title: Acid-fastness of fungi in blastomycosis and histoplasmosis.
abstract: In 60% of the infections caused by Blastomyces dermatitidis and in 47% of the infections caused by Histoplasma capsulatum, some of the organisms are acid-fast in tissue sections. Treatment with 1N hydrochloric acid at 60 degrees C abolishes the acid-fastness of H capsulatum, which indicates that the acid-fastness may be related to mycolic acid. Organisms of B dermatitidis, however, remain acid-fast in 83% of the sections treated with acid. The presence of acid-fastness in small cells can aid in the differentiation of B dermatitidis and H capsulatum from Cryptococcus neoformans and Candida albicans, Persistent acid-fastness of organisms after treatment with heated acid helps identify B dermatitidis in tissue sections, especially when the strain is small or in other ways atypical.
mesh_terms: D001758:Blastomyces / Q000166:cytology*; D001759:Blastomycosis / Q000382:microbiology*; D006658:Histoplasma / Q000166:cytology*; D006660:Histoplasmosis / Q000382:microbiology*; D013194:Staining and Labeling