Molecular identification of Candida albicans isolated from the oncology patients at four university hospitals in Mazandaran province [2005-6]

ABSTRACT

Early detection of Candida species in body site could improve the survival of the immunosuppressed patients by allowing the initiation of specific treatment while the fungal biomass is still low. The aim of this study was the identification of Candida albicans isolated from the oncology patients by molecular methods. Sixty two of Candida albicans isolated identified by phenotypic methods [color of colony on CHROMagar medium, germ-tube formation in horse serum, chlamydospore formation on Cornmeal agar with 1% Tween 80]. DNA was extracted by using a glass bead/phenol-chloroform method. The oligonucleotide primer pairs [NL1/NL4] were used to amplify a 620bp fragment of D1/D2 region of large submit [26s] ribosomal DNA gene. PCR-products were electrophoresed in a 1.5% agarose gel. Eighteen PCR-amplified products sequenced and results were evaluated by online BLAST software. Multiple sequence alignment was performed by using online CLUSTAL-W [version 1.83] software. The BLAST search revealed that all of products were Candida albicans. All sequences showed >99% similarity when compared with known reference sequences at the Gene-Bank. Four different strains were obtained of albicans species, including AA 1622b [13 samples], 24698 [3 samples], TA 62 [1 samples] and 551 FC [1 sample]. A total of 131 nucleotide exchange sites were revealed. The dominant species by phenotypic approaches was Candida albicans. In addition, identification of Candida albicans by [26S] rDNA sequencing was 100% concordant to the results obtained by the phenotypic methods: