Morphological conversion of 13 strains of three dimorphic fungi in tap and stream water.

Various strains of Sporotrichum schenckii, Histoplasma capsulatum and Paracoccidioides brasiliensis show partial to complete (ca 70%) conversion to yeast when the mycelial culture is grown on Sabouraud's dextrose agar at 25degreesC and palced in tap or stream water at 37degreesC. Conversion (ca 70%) to mycelial phase occurs when the yeast culture is grown on brain heart infusion agar at 37degreesC and then placed in tap or stream water at 25degreesC. It was observed that, with the dimorphic organisms and strains tested, enriched medium is not necessary for partial conversion to either phase because it occurs in tap and stream water. The change in morphology is assumed to be principally due to temperauture change, as reported for Blastomyces dermatitidis and H. capsulatum by other workers.