Abstract: Objective To investigate the pathogenicity, susceptibility to antifungal drugs, and electrophoretic karyotype of clinically uncommon pathogenic yeasts. Methods The immunocompromised mice, induced by hydrocortisone and cyclophosphamide, were challenged by the yeast cells, then their survival periods were observed, and the CFU/mL of yeast cells in the important internal organs were counted. The minimal inhibitory concentrations(MICs) of the yeasts were determined with microdilution method. The genomic total chromosomes of these yeasts were separated by PFGE. Results The pathogenicity of 10 yeasts,namely, Torulopsis glabrata, Sporobolomyces salmonicolor,Saccharomyces cerevisiae,Cryptococcus laurentii, Debaryomyces hansenii,Torulopsis globular,Trichosporon beigelii, Klocckera lemom, Geotrichum candidum and Rhodotorula rubra,varied and all were less virulent than that of C.albicans. The susceptibility of the yeasts to two antifungal agents,fluconazole and ketoconazole, was different.The PFGE pattern showed that different yeasts had different electrophoretic karyotypes. The numbers of chromosomes were 12 for S. cerevisiae,6 for T.beigelii,9 for D.hansenii,8 for T.glabrata,4 for K.lemom,7 for R.rubra,5 for S.salmonicolor and 10 for C.laurentii. Conclusion The clinically uncommon yeasts tested yield different pathogenicity, antifungal susceptibility and genotypes. These data could be helpful for the clinical diagnosis and treatment of mycoses caused by these yeasts.

Key words: Yeasts, Microbial sensitivity tests, Genes, fungal