Abstract: Objective To study the molecular identification method of Sporothrix schenckii based on the nucleotide sequences in internal transcribed spacer region 2 of ribosomal DNA (rDNA) genes. Methods Species-specific primers were used to amplify the internal transcribed spacer region 2 of rDNA of 22 clinical isolates of Sporothrix schenckii and 12 strains of dematiaceous fungi. Totally 11 strains of Sporothrix schenckii were sequenced and analyzed, in which 1 strain came from the US and the others were isolated from different areas in China. A pair of species-specific oligonucleotide primers (SSP) were designed based on the ITS2 sequence. With the species-specific primers, rDNA of Sporothrix schenckii and dematiaceous fungi were amplified by PCR. Results Sequencing and analysis showed that internal transcribed spacer region 2 of rDNA gene was conservative in Sporothrix schenckii. A 300 bp fragment was obtained from 22 strains of Sporothrix schenckii, but not from the other species. Conclusions This method is specific, sensitive and reliable for the identification of Sporothrix schenckii and could be used for clinical molecular diagnosis.

Key words: Sporothrix, DNA primers, DNA, ribosomal spacer