Recurrent vulvovaginal candidiasis: a dynamic interkingdom biofilm disease of Candida and Lactobacillus

This study aimed to assess a panel of clinical samples from healthy women and those with RVVC to investigate the influence of Candida, the vaginal microbiome, and how their interaction influenced disease pathology. 16S rRNA sequencing characterised disease by a reduction in specific health-associated Lactobacillus species such as L. crispatus, coupled with an increase in L. iners. In vitro analysis showed Candida albicans clinical isolates are capable of heterogeneous biofilm formation and show the presence of hyphae and C. albicans aggregates in vaginal lavage. Additionally, the ability of Lactobacillus to inhibit C. albicans biofilm formation and biofilm-related gene expression was demonstrated. Using RNA sequencing technology, we were able to exploit a possible mechanism by which L. crispatus may aim to re-establish a healthy vaginal environment through amino-acid acquisition from C. albicans. This study suggests RVVC is not entirely due to an arbitrary switch in C. albicans from commensal to pathogen and understanding interactions between the yeast and vaginal Lactobacillus species may be more crucial to elucidating the cause of RVVC and developing appropriate therapies.