Abstract: Objectives In order to develop a rapid microsatellite genotyping assay for inter-strain differentiation of Candida albicans isolates and understand the transmission characteristics of the infections.Methods DNA was extracted from C.albicans isolates from genitals,anal canals and oral cavities of 39 women and 27 men with genital candidiasis.The microsatellite sequences in stabel genes(CDC3,EF3 and HIS3) were amplified by a fluorescence labeled PCR.Fluorescent signals were read with an automatic sequencer,and the data were collected with GeneScan software followed by genotyping with Genotyper software to analyze polymorphic microsatellite loci.Results Combined analysis of the 3 microsatellite markers showed 18 gene allele associations in C.albicans from genital sites of all men and women,including 10 in women,11 in men and 3 in both.The allele associations of dominant pathogenetic strains for both sexes were 116:124,122:131,160:200,which covered 50% of pathogenetic infection.Three common allele associations for both sexes covered 71% of all infections.Genitals and anal canals shared strains of same allele associations in 80% of women and in only 3.8% of men.The strains of same allele associations were identified in both genitals and mouth in 2.7% of women but in none of men.In their genital sites 71% of couples shared the same allele strains,of which 80% were the dominant pathogenetic strains identified in both sexes.Conclusions The improved microsatellite genotyping assay is useful for rapid differentiation,identification of infective source,and contact tracing of C.albicans infection.There are pathogenetic C.albicans strains with predominant allele associations in genital infections.

Key words: Candida albicans, Microsatellite repeats, Polymorphism,genetic