The Biology of Candida sp.

 

C. albicans is an opportunistic organism and the most frequently isolated fungal pathogen in humans.  It is present as an harmless organism in the gastrointestinal tracts of most healthy individuals but can cause life-threatening diseases in situations that affect immunological competence (for example patients with serious burns, undergoing chemotherapy or transplantation surgery).  Candida infection is becoming one of the most prominent causes of morbidity and mortality in the last few years because of a rapid increase in people with HIV infections and acquired immuno-deficiency syndrome (AIDS).

           

 C. albicans is a diploid yeast with no naturally occurring sexual cycle. One of the most distinctive features of C. albicans is its polymorphism: it can grow and switch between the budding and the filamentous (true and pseudo-hyphal) forms.  A correlation between the hyphal form and its virulence has been proposed.  Several lines of evidence, however, suggest that instead of just one virulence factor, there are multiple unidentified factors that may contribute to the pathogenicity of the organism.

C. dubliniensis was first identified and reported as a separate taxon in 1995.  Phylogenetically C. dubliniensis is very closely related to C. albicans. C. dubliniensis is the only Candida species, other than C. albicans, that can produce true hyphae. C. dubliniensis is particularly common in oral candidosis in HIV-infected individuals throughout the world.  Interestingly, in spite of a high degree of similarity between C. albicans and C. dubliniensis, the latter is much less pathogenic and thus an attractive subject for comparative genomic research.