Abstract

One accredited species, Candida albicans subspecies dubliniensis, has been proposed to replace the existing designations of Candida dubliniensis. The study of the genetic diversity among the clinical isolates of C. albicans and C. dubliniensis was performed based on the amplified transposable intron region in the 25S rRNA gene. This study attempts to verify the unequivocal understanding of the genetic relationship between C. albicans and C. dubliniensis. Twenty (20) isolates of C. albicans and C. dubliniensis were studied using the method of typing by rDNA, restriction fragment length polymorphism (RFLP), random amplification polymorphism DNA-polymerase chain reaction (RAPD-PCR) and intron sequencing in the 25S gene. The results reveals that the specific primer pair CABF59F and CADBR125R was the successfully amplified target for all the C. albicans isolates and three isolate of C. dubliniensis. The Candida isolates revealed a genetic pattern based on the analysis of the RAPD-DNA fingerprinting pattern. The RFLPs generated by Hhal and Hae 111 enzymes elucidated similar recognition sites for both the C. albicans and C. dubliniensis isolates. Analysis of the intron sequence in the 25S gene region of the genotype C. albicans and C. dubliniensis showed identical with only a few differences in the base substitution. The sequence variations appear among the same isolates in each species. In all the cases, the clinical isolates of both species showed a percentage sequence similarity of >99.5%. This result emphasizes a high indication of similarity between C. dubliniensis and C. albicans. It was concluded that the taxonomic position of C. dubliniensis was puzzled due to insufficient genetic and phenotypic characters to warrant species status. Variations were occasionally observed to occur among the same isolates, within the same species; however, this indication is applied to other taxonomic criteria between them, with no credibility for the great differences observed between C. dubliniensis and C. albicans. This is the final taxonomic decision for C. dubliniensis to merit an amendment in order to be included as C. albicans subspecies dubliniensis stat. et comb. nov. C. dubliniensis with a revised synonymy for C. albicans.

Key words: Amendment, Candida albicans ssp. dubliniensis stat. et comb. nov, restriction fragment length polymorphism (RFLP), random amplification polymorphism DNA (RAPD), polymerase chain reaction (PCR), sequence, phylogenetic tree.