[Rapid identification of clinical yeast species by single-strand conformation polymorphism analysis of 26S rDNA D1/D2 domain].

OBJECTIVE

To investigate the reliability of single-strand conformation polymorphism (SSCP) analysis of 26S rDNA D1/D2 domain for rapid identification of clinical yeast species and to examine the distribution of the yeast species in clinical strains from Beijing.

METHODS

Type and authentic strains of five common pathogenic yeast species were used as references. Approximately 260 yeast strains with diversified clinical origins were collected from four hospitals located in Beijing. The 26S rDNA D1/D2 domain of each strain was amplified by PCR and subjected to SSCP or sequence analysis.

RESULTS

SSCP analysis showed that the Candida strains with slight sequence differences in the D1/D2 domain could be effectively detected. The common pathogenic Candida species, including C. albicans, C. parapsilosis, C. tropicalis, C. glabrata and C. krusei, were clearly distinguished from each other by their SSCP patterns of PCR amplified D1/D2 domain products. Twenty species belonging to 10 genera were identified from the approximately 260 clinical yeast strains based on SSCP pattern comparison for the common species and D1/D2 sequence analysis for the uncommon species. The dominant species and their frequencies were: C. albicans (57.7%), C. parapsilosis (10.0%), C. tropicalis (9.2%), C. glabrata (6.7%) and C. krusei (5.8%).

CONCLUSION

The results indicated that PCR-SSCP analysis of D1/D2 is a powerful approach for rapid species identification of clinical yeast strains. The most common clinical yeast species was C. albicans in Beijing but the increasing trend of non-albicans Candida species was observed.