Microbiota in vaginal health and pathogenesis of recurrent vulvovaginal infections: a critical review Original paper

What was reviewed?

This review analyzed existing knowledge of vaginal microbiota (VMB) in relation to vaginal health and recurrent vulvovaginal infections (RVVI), focusing specifically on bacterial vaginosis (BV), vulvovaginal candidiasis (VVC), and trichomoniasis (TV). The authors critically assessed current insights derived from advanced molecular techniques, highlighting how both bacterial and fungal communities influence vaginal health, and discussed the interactions among these communities and their role in the pathogenesis of recurrent infections.

Who was reviewed?

This critical review evaluated literature from diverse sources, including peer-reviewed studies identified through databases such as PubMed and Google Scholar. Included were studies employing both culture-dependent and culture-independent methods to characterize vaginal microbial communities in healthy women and those suffering from recurrent vaginal infections, including bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis.

What were the most important findings?

The review highlights the complexity and variability of vaginal microbiota, challenging the traditional view that Lactobacillus dominance universally signifies vaginal health. While Lactobacilli typically protect vaginal health by producing lactic acid, maintaining acidic conditions that prevent infections, certain species such as L. iners can instead contribute to instability and disease susceptibility. In bacterial vaginosis, reduced Lactobacilli and increased anaerobes, especially Gardnerella vaginalis, play a critical role. G. vaginalis contributes significantly to disease through biofilm formation and secretion of virulence factors, including vaginolysin and sialidases.

For vulvovaginal candidiasis and trichomoniasis, microbial interactions are key determinants of disease progression. Candida albicans, usually harmless in its yeast form, can shift to a pathogenic hyphal state under elevated pH or disrupted microbiota, highlighting crucial interactions between bacteria and fungi in maintaining health. In trichomoniasis, Trichomonas vaginalis actively damages vaginal epithelial cells and suppresses beneficial Lactobacilli through mechanisms including protease secretion and biofilm formation, exacerbated by symbiotic interactions with mycoplasmas and dsRNA viruses that further enhance virulence.

What are the greatest implications of this review?

This review stresses the importance of understanding individual variability and complex interactions within the vaginal microbiota when managing recurrent vulvovaginal infections. It emphasizes that traditional beliefs, such as universal Lactobacillus dominance indicating vaginal health, are oversimplifications. This knowledge demands that clinicians adopt more nuanced diagnostics and personalized approaches to treatment. Furthermore, the authors highlight critical gaps in our understanding of the fungal and parasitic components of the vaginal microbiota, suggesting a need for further research utilizing comparative genomics and longitudinal microbiome profiling to guide improved clinical management strategies for RVVI.