The impact of fluconazole use on the fungal and bacterial microbiomes in recurrent Vulvovaginal Candidiasis (RVVC): a pilot study of vaginal and gastrointestinal site interplay.

Purpose: Recurrent Vulvovaginal Candidiasis (RVVC) is a problematic clinical condition for which fluconazole treatment is commonly prescribed. This study investigated the interkingdom vaginal and gastrointestinal microbiomes of RVVC patients who use fluconazole intermittently or as longer-term maintenance therapy for symptom management and compared them to healthy controls.
Methods: Vaginal swabs and fecal samples were collected. A novel interkingdom analysis was performed using 16 S rRNA and ITS1 gene sequencing to compare the diversity and taxonomic composition of vaginal microbiome (VMB) and gastrointestinal microbiome (GIMB).
Results: Twenty-seven women participated: 10 intermittent users and healthy controls and 7 maintenance therapy. The study revealed that microbiomes of fluconazole users do not differ in diversity metrics from healthy controls. RVVC patients using intermittent fluconazole displayed a higher abundance of vaginal C. albicans than healthy controls. Candida species pairings were not commonly observed between sites in individuals and, as such a fecal reservoir is unlikely to be implicated in recurrent symptomatology. In many of the RVVC non-Candida fungal spp. were identified in the vaginal microbiome. Users of fluconazole displayed elevations of the CST-I (Community State Type 1) associated bacterium L. crispatus. All participants displaying vaginal Candida spp. belonged to either bacterial CST-I or CST-III (Community State Type 3- L. iners associated).
Conclusion: To our knowledge, this is the first study to compare the interkingdom VMB-GIMB of women with RVVC using oral fluconazole. As fluconazole users in this study represent a typical RVVC population, trends observed in microbial abundance require further analysis to establish fluconazole's long-term microbiome safety. Examining the microbiome at both sites adds to the current understanding of microbial associated with the condition.
Competing Interests: Declarations. Ethics approval and consent to participate: The study was performed in accordance with the Declaration of Helsinki (2000) for human studies. Ethics approval was obtained for the study from Griffith University Human Research Ethics Committee (GU Ref No: 2021/674). All participants provided written informed consent to participate. Clinical trial number: not applicable. Competing interests: The authors declare no competing interests.
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