In vivo and in vitro characteristics of six Paracoccidioides brasiliensis strains.

The yeast-like forms of six P. brasiliensis strains were characterized and compared using in vitro (growth curve determination) and in vivo (pathogenicity to sensitive inbred mice) criteria. Strains Pb 18 and Pb 265 which behaved similarly in vitro, showing low counts of fungi and long mean generation times, were respectively the most and the least pathogenic strains. Strains Pb 2052 and IVIC Pb 267, which grow abundantly in vitro were, respectively virulent and avirulent. Strains Pb SN and IVIC Pb 9 behaved similarly both in vitro and in vivo displaying an intermediate pattern of virulence and growing conditions.