The vaginal mycobiome: A contemporary perspective on fungi in women's health and diseases

Abstract

Most of what is known about fungi in the human vagina has come from culture-based studies and phenotypic characterization of single organisms. Though valuable, these approaches have masked the complexity of fungal communities within the vagina. The vaginal mycobiome has become an emerging field of study as genomics tools are increasingly employed and we begin to appreciate the role these fungal communities play in human health and disease. Though vastly outnumbered by its bacterial counterparts, fungi are important constituents of the vaginal ecosystem in many healthy women. Candida albicans, an opportunistic fungal pathogen, colonizes 20% of women without causing any overt symptoms, yet it is one of the leading causes of infectious vaginitis. Understanding its mechanisms of commensalism and patho-genesis are both essential to developing more effective therapies. Describing the interactions between Candida, bacteria (such as Lactobacillus spp.) and other fungi in the vagina is funda-mental to our characterization of the vaginal mycobiome.

Keywords: Candida albicans; fungal community; fungi; infectious diseases; microbial ecology; microbiome; microbiota; mycobiota; vagina; vulvovaginal candidiasis.

Figure 1.

Interactions between Candida and microbiota at the mucosal interface have profound effects on the vaginal ecosystem. Metabolites and small molecules made by the microbiota affect the metabolism and morphology of Candida species. Changes in microbiota relative abundance also impact the abundance of Candida and its ability to access the mucosal surface, where invasion occurs. In healthy states, when microbiota-derived lactic acid is produced, Candida can alter host cytokine production and promote anti-inflammatory signaling. The contribution of bacterial-fungal interactions to the ecology of the vaginal microbiota remains to be described.