Studies in sporotrichosis: fungal morphogenesis and pathogenicity in differing environments.

Sporothrix schenckii exhibits different morphology and pathogenic properties according to the source and circumstances of its growth. The present study considers the morphology and experimental pathogenicity in relation to - the 'wild' strains; the possible circumstances enhancing pathogenicity in strains recovered from the soil; the rate and nature of the transformational steps in morphology, in human and experimental infections by established pathogenic strains; the elimination of pathogenic strains to the surface of clinical lesions, enabling a simplified diagnostic proof of infection; the rate and nature of the reversion of pathogenic forms to the 'wild' type when the constraints of the host are lessened; the plasticity of conidium-pigmentation as a sign of pathogenicity; the morphological conversions on moist wattle-wood as occur in the Gold Mines; and a note on the therapeutic value of itraconazole. Host resistance is seen to play a larger part in morphology of the pathogenic phase, and exhaustion of natural food resources as the generator of potentially pathogenic forms.