Identification of Candida dubliniensis, based on ribosomal DNA sequence analysis

Differentiation of Candida albicans and the recently described C, dublinien sis has proven difficult due to the high degree of phenotypic similarity of these species. The present study examines sequence variations in the ribos omal DNA (rDNA) intergenic transcribed spacer (ITS) regions of C. albicans (n = 5) and C. dubliniensis (n = 7) strains, with a view to identifying seq uence differences that would enable consistent differentiation of these two species by restriction fragment length polymorphism (RFLP) analysis. The I TS1 and ITS2 regions, together with the entire 5.8S rRNA gene of the strain s, were amplified by the polymerase chain reaction (PCR), using primers ITS 1 and ITS4. PCR products from both C. albicans and C. dubliniensis were of similar size (around 540 bp); however, sequence analysis revealed over 20 c onsistent base differences between the products of the two species. On the basis of sequence variation, the restriction enzyme MspA1 I was selected an d used to differentiate the PCR products of C, albicans and C. dubliniensis by RFLP analysis. MspA1 I yielded two discernible fragments from C. albica ns PCR products, whilst those from C. dubliniensis appeared undigested, the reby providing an approach to differentiate the two species.