Uncovering the Yeast Diversity in the Female Genital Tract: An Exploration of Spatial Distribution and Antifungal Resistance

A molecular view on the interference established between vaginal Lactobacilli and pathogenic Candida species: Challenges and opportunities for the development of new therapies

Vaginal infectious diseases caused by viruses and bacteria have been linked to the occurrence of dysbiosis, that is, a reduction in the abundance of the normally dominating vaginal Lactobacillus species. Mucosal infections in the vagina and/or vulva caused by Candida species, usually known as vulvovaginal candidiasis (or VVC), are among the leading causes of diseases in the vaginal tract. The existence of a clear link between the occurrence of dysbiosis and the development of VVC is still unclear, although multiple observations point in that direction. Based on the idea that vaginal health is linked to a microbiota dominated by lactobacilli, several probiotics have been used in management of VVC, either alone or in combination with antifungals, having obtained different degrees of success. In most cases, the undertaken trials resorted to lactobacilli species other than those indigenous to the vaginal tract, although in vitro these vaginal species were shown to reduce growth, viability and virulence of Candida. In this paper we overview the role of lactobacilli and Candida in the vaginal micro- and myco-biomes, while discussing the results obtained in what concerns the establishment of interference mechanisms in vivo and the environmental factors that could determine that. We also overview the molecular mechanisms by which lactobacilli species have been shown to inhibit pathophysiology of Candida, including the description of the genes and pathways determining their ability to thrive in the presence of each other. In a time where concerns are increasing with the emergence of antifungal resistance and the slow pace of discovery of new antifungals, a thorough understanding of the molecular mechanisms underneath the anti-Candida effect prompted by vaginal lactobacilli is of utmost importance to assure a knowledge-based design of what can be a new generation of pharmaceuticals, eventually focusing therapeutic targets other than the usual ones.

Study of Ecological Relationship of Yeast Species with Candida albicans in the Context of Vulvovaginal Infections

The role of the fungal community, the mycobiota, in the health of the vagina is currently an important area of research. The emergence of new sequencing technologies and advances in bioinformatics made possible the discovery of novel fungi inhabiting this niche. Candida spp. constitutes the most important group of opportunistic pathogenic fungi, being the most prevalent fungal species in vulvovaginal infections. However, fungi such as Rhodotorula spp., Naganishia spp. and Malassezia spp. have emerged as potential pathogens in this niche, and therefore it is clinically relevant to understand their ecological interaction with Candida spp. The main aim of this study was to evaluate the impact of yeasts on Candida albicans' pathogenicity, focusing on in-vitro growth, and biofilm formation at different times of co-culture and germ tube formation. The assays were performed with isolated species or with co-cultures of C. albicans (ATCC10231) with one other yeast species: Rhodotorula mucilaginosa (DSM13621), Malassezia furfur (DSM6170) or Naganishia albida (DSM70215). The results showed that M. furfur creates a symbiotic relationship with C. albicans, enhancing the growth rate of the co-culture (149.69%), and of germ tube formation of C. albicans (119.8%) and inducing a higher amount of biofilm biomass of the co-culture, both when mixed (154.1%) and preformed (166.8%). As for the yeasts R. mucilaginosa and N. albida, the relationship is antagonistic (with a significant decrease in all assays), thus possibly repressing the mixture's pathogenicity. These results shed light on the complex interactions between yeasts in the vaginal mycobiome.

VULVOVAGINAL CANDIDIASIS AFTER GYNECOLOGICAL SURGERIES AND ADVERSE PREGNANCY OUTCOME IN UKRAINE: A MULTICENTRE STUDY

OBJECTIVE

The aim: To investigate the epidemiology and microbiology of vulvovaginal candidiasis (VVC) after gynecological surgeries, and adverse pregnancy outcomes in Ukraine.

PATIENTS AND METHODS

Materials and methods: Multicenter prospective cohort study was conducted from January 2020 to December 2022 and recruited pregnant and non-pregnant women aged 15-65 years who had sought medical help for vaginal dysbiosis the seven medical clinic from five regions of Ukraine.

RESULTS

Results: Between 2020 and 2022, 2,341 women were followed in gynecological practices, and 1,056 (41.5%) women were diagnosed with VVC during the same period. Of the total VVC cases, 31.9% were in non-pregnant and 68.1% in pregnant women. The use of antibiotics (OR=3.48), use hormonal contracep¬tives (OR=2.75) and pregnancy (OR=1.13) were associated with an increase in the risk of VVC diagnosis. Diabetes mellitus (OR=0.44) were additional risk factors. The most common pathogen of VVC was C. albicans, Nakaseomyces glabratus (C. glabrata), followed by Pichia kudriavzevii (C. krusei), C. parapsilosis, C. tropicalis, C. kefyr, C. guillieromondii, C. lusitaniae, and C. rugosa. We found no significant difference in adverse pregnancy outcomes between Candida-positive and Candida-negative women.

CONCLUSION

Conclusions: Vulvovaginal candidiasis after gynecological surgeries in Ukraine is a common medical problem in women that is associated with significant morbidity, and hence frequent medical visits. High prevalence rate of vulvovaginal candidiasis in the present study warrants, the importance of conducting continuous epidemiological surveys to measure changes in species distribution from C. albicans to non-albicans Candida species in Ukraine.