Characterization of Clinical and Environmental Isolates of Cryptococcus neoformans/Cryptococcus gattii Complex Maintained in Yeast Culture Collection in São Paulo, Brazil

Objective: As isolates of Cryptococcus are frequently kept collection stocks in institutions, sometimes without proper characterization, we sought to determine the genotype profiles, protease and phospholipase activities “in vitro” and the susceptibility testing for azoles and amphotericin B. Methodology: 84 isolates from several regions of Brazil (40 samples from clinical origin and 44 isolates from environmental origin) were maintained at the microorganism’s bank of the Biomedical Science Institute (ICB-USP) of the São Paulo University, in São Paulo, Brazil. This isolates was submitted fungal strains determination, DNA extraction and purification, determination of genotype by URA5 gene RFLP of CGB-positive isolates, protease and phospholipase activity and susceptibility to antifungals. Results: Of six CGB positive isolates tested by RFLP-PCR, only four presented a genomic profile consistent C. gattii species (VGII), while two other were C. neoformans (VNI and VNIII), indicating the existence of canavanine-resistante C. neoformans isolates in the culture collections. The clinical isolates secreted higher levels of phospholipase and environmental isolates but no differences were observed for the protease levels. Almost all isolates were sensible to azoles and amphotericin B. Conclusion: We point out in this research the existence of C. neoformans strains resistant to canavanine and intrinsic characteristic of C. gatti. These results demonstrate the importance to perform a detailed characterization of isolates kept in culture collections.