H. capsulatum, a dimorphic fungus, is found in soil heavily contaminated with bird droppings. Which of the following statements best describes the presence of the organism in tissue biopsies?
Histoplasma capsulatum is a dimorphic fungus that forms two types of spores: tuberculate macroconidia and microconidia. Inhalation of the microconidia transmits infection. Inhaled spores (microconidia) are engulfed by macrophages and develop into yeast forms. Most infections remain asymptomatic; small granulomatous foci heal by calcification. However, pneumonia can occur. The heterophile antibody test is useful for early diagnosis of infectious mononucleosis. The figure below illustrates the oval budding yeasts.
Yeasts with broad-based bud
Single-cell yeasts with pseudohyphae
Arthrospores
Oval budding yeasts inside macrophages
Mycology