Molecular and phenotypic analysis of Candida dubliniensis: a recently identified species linked with oral candidosis in HIV-infected and AIDS patients.

The discovery and characterisation of a novel species of Candida, termed Candida dubliniensis, associated with oral candidosis in HIV-infected individuals is described. These organisms share several phenotypic characteristics in common with Candida albicans and Candida stellatoidea, including the ability to produce germ tubes and chlamydospores. However, in contrast to these latter two species, C. dubliniensis isolates produce abundant chlamydospores, which are often arranged in contiguous pairs, triplets and other multiples suspended from a single suspensor cell. They belong to C. albicans serotype A and exhibit atypical substrate assimilation profiles. Genomic DNA fingerprinting analysis with the C. albicans-specific probe 27A and five different oligonucleotide probes consisting of short repeat sequence-containing motifs, demonstrated that C. dubliniensis has a distinct genomic organisation relative to C. albicans and C. stellatoidea. This was confirmed by karyotype analysis and random amplified polymorphic DNA (RAPD) analysis. Comparison of 500 bp of the V3 variable region of the large ribosomal subunit genes from 14 separate C. dubliniensis isolates and the corresponding sequences from C. albicans, C. stellatoidea, C. tropicalis, C. glabrata, C. parapsilosis, C. kefyr and C. krusei demonstrated that the C. dubliniensis isolates formed a homogenous cluster (100% similarity), representing a discrete taxon within the genus Candida that was significantly different from the other species analysed.