Prospective Studies of Vaginal Yeast and Microbiome Related to Vulvovaginal Candidiasis in Canadian Females

Vulvovaginal candidiasis (VVC; colloquially referred to as a 'yeast infection') is a prevalent mucosal infection caused by Candida spp. that affects ~75% of women at least once in their life. VVC usually responds well to treatment, yet a small but significant fraction of women experience recurrent yeast infections even with weekly treatment. A further complication in understanding the causes of recurrent infections is that approximately one in five females have vaginal yeast present without any symptoms at any given point. The link between fungi, other microbes in the vagina ("microbiome"), and the human immune system remain poorly understood in the switch from having yeast present in the vagina without any symptoms and symptomatic yeast infections. Fungi also compose a normal component of the microbiome at other sites in the body (e.g., oral, skin, gastrointestinal tract, rectum) where they may serve as a source of re-infection following treatment.

In addition to the commonly prescribed 'first choice' antifungal drug fluconazole, a second-line treatment, boric acid, has shown promise in the literature and has been used locally with success at increasing the time between recurrent infections. A drawback of this therapy, however, is cost, as it is a compounded medication, and patients have to pay out of pocket. The purpose of this study is to understand how the yeast and bacterial microbial communities differ for females with recurrent infections from females with their first yeast infection and females with vaginal yeast present without any symptoms, and to track yeast diversity following treatment with either boric acid or fluconazole. The investigators hypothesize that they will identify multiple subpopulations of yeast at multiple anatomical body sites in females with VVC and recurrent VVC. They anticipate finding evidence for recurrent infection from secondary sites by linking genomic diversity of vaginal yeast strains during symptomatic infection to strains from other body sites. They hypothesize that yeast isolated from females with recurrent infections will exhibit different drug response phenotypes than yeast from females with asymptomatic vaginal yeast. They hypothesize that the vaginal microbiome of post-treatment patients treated with boric acid will differ from that of fluconazole. Combined, they hypothesize that post-treatment response will differ between the drugs, indicating that treatment specifics influence the vaginal environment.