Comparative virulence and immunodiffusion analysis of Petriellidium boydii (Shear) Malloch strains isolated from feedlot manure and a human mycetoma.

The virulence to mice of a Petriellidium boydii strain isolated from feedlot manure was compared with that of a strain from a human mycetoma. Washed spores suspended in 5% hog gastric mucin were injected intraperitoneally into non-inbred female albino Swiss mice. In 21 days, the mycetoma strain killed 95% of the test animals whereas injection of eight times as many feedlot strain spores resulted in only 28% mortality. A progressive, exclusively sinistral (leftsided) torticollis was the most obvious symptom of experimental petriellidiosis. Mycelia bearing annellospores were observed in PAS-stained sections of most internal organs, including the brains, of the test animals. Immunodiffusion analyses were conducted on soluble antigen preparations with concentrated antisera produced in rabbits using live spore suspensions. The two strains contained common antigen but the proportions of two were significantly different.