Candida albicans, abbreviated as C. albicans, belongs to the genus of Candida of family of Saccharomycetaceae. C. albicans, a diploid yeast commensal and opportunist pathogen, has evolved unusual mechanisms for maintenance of genetic diversity in the absence of a complete sexual cycle. These include chromosomal polymorphisms, mitotic recombination events, and gains and losses of heterozygosity, superimposed on a fundamentally clonal mode of reproduction. 50–90% of all cases of candidiasis in humans caused by C. albicans, especially severe morbidity and mortality happened in those patients if they had a deficient function of immune protection, such as AIDs, organ or bone marrow transplantation, cancer chemotherapy. Figure 1 shows the schematic of Candida albicans:
Fig. 1 Model of Candida Albicans
The fungus is found as a commensal in the digestive tract of many, if not most, individuals. It can cause diseases ranging from commonly encountered superficial infections (primarily affecting oral and vaginal sites) to rare, life-threatening, hematogenously disseminated, invasive diseases, depending on the nature and extent of a host’s underlying condition.
The study of epidemiology of Candida Albicans suggests that most individuals carry a single strain type of C. albicans, as well as a few cases that contain more than one strain type. Evidence shows that many individuals infect a mixture of strain types including a range of minor variants differ from those who harbor only one strain type of C. albicans in genetic heterozygosity. Further research indicates that replacement of strain type of C. albicans has happened in host, even though this phenomenon isn’t so much common than carriage of a single type with minor variants.
The family tree provides clear evolutionary associations of relationships of strain types of C. albicans to us based on geographical evidence, but those relationships have become blurred because of a high global rate of human travel, and thus facilitates transmission of strain types between countries. The most populous Candida Albicans strain clade accounts for approximately 33% of all isolates and is found universally, suggesting this strain cluster may be better adapted for human commensalism than other types.
The famous and important features of the C. albicans genome is the event of numeric and structural chromosomal rearrangements which play as means to generate genetic diversity, called chromosome length polymorphisms, chromosome deletions, reciprocal translocations and trisomy of individual chromosomes. These karyotypic changes lead to alterations in the phenotype of Candida Albicans. Currently, the most advanced methods for typing individual isolates of C. albicans are those based on DNA sequence determination, including typing of tandem microsatellite repeat sequences, single-nucleotide polymorphism arrays and multilocus sequence typing.