Specific identification of Candida albicans and Candida dubliniensis by PCR using species-specific primers

The aim of our study was to evaluate the effectiveness of phenotyping and genotyping methods for the identification of Candida albicans and Candida dubliniensis. Phenotyping methods used are colony colour on CHROMagar Candida medium, growth at 45 degrees C, TTC (2.3,5-triphenyl-tetrazolium chloride) reduction, germ tube and chlamydospores formation, and API 20C AUX. We also used C. albicans and C. dubliniensis specific primers for identification performed with genotyping methods. DNAs of C. albicans reference strains, different Candida species, Cryptococcus neoformans, mycelial fungi, bacterial strains and human DNA were used as a template in order to evaluate the specificity of the primers. These primers yielded a 175-base-pair product only when C. albicans DNA exists; however when other DNAs (except two isolates that are phenotypically identified as C. dubliniensis and C. tropicalis) exist no product appeared. In another PCR assay conducted by using C. albicans DNA and C. dubliniensis specific primers, no product was observed. Candida albicans and C. dubliniensis specific primers were designed by Mannarelli and Kurtzman. Detection limit of C. albicans primers was found to be 19 pg chromosomal DNA. In order to verify phenotypical definition with PCR amplification, C. albicans and C.dubliniensis specific primers were exposed to PCR by using DNAs that belong to 25 phenotypically defined oral Candida isolates.