Investigating the microbial composition of Recurrent Vulvovaginal Candidiasis samples and biofilm formation of Candida clinical isolates

Abstract

Recurrent vulvovaginal candidiasis (RVVC) is a chronic and debilitating condition that is estimated to affect 138 million women annually. In spite of this high prevalence and its associated economic burden, pathogenesis of disease is poorly understood. The biofilm-forming yeast Candida albicans is reported as the causative pathogen in up to 90% of VVC cases and around 50% in RVVC disease. Despite the identification of Candidabiofilms on the vaginal mucosa, their associated therapeutic challenge in RVVC is still disputed. A panel of 100 HVS and cervico-vaginal lavage (CVL) samples were obtained for this trial. Patient questionnaires collected data on patient’s vaginal thrush history, treatments and any contraception currently used. Microbiological screening of clinical samples was performed, and microbiome analysis was utilized to determine predominant microbes present in each cohort. Non-C. albicans species (NCAS) such as intrinsically azole-resistant C. glabrata were found to account for 27% of RVVC cases, notably higher than historically reported. Additionally, microbiome analysis showed a reduction in Lactobacillus species associated with a healthy microbiome in RVVC compared to health. This study supports a previous clinical trial by our group using 300 HVS to investigate the epidemiology of RVVC showing an increasing prevalence of NCAS responsible for disease. Additionally, this work strengthens the hypothesis that formation of Candida biofilms on the vaginal mucosa could negatively impact clinical treatment. Further research to identify triggers for RVVC, and the pathogenesis of the predominant microbes involved, could considerably improve prevention and treatment options for women with recurrent, azole-resistant infections.