Impact of stress, diet and antibiotic usage on vaginal microbiota and antibiotic resistance

In reproductive-aged women, the vaginal microbiome is typically dominated by various species of lactobacilli. These beneficial bacteria play a key role in maintaining vaginal health and eubiosis by preventing the colonization and proliferation of harmful microorganisms through several mechanisms. The depletion of lactobacilli in parallel with the increase of different species of anaerobic bacteria results in a dysbiotic condition called bacterial vaginosis (BV). Longitudinal studies have shown that the composition of the vaginal microbiome is influenced by various local and systemic factors, such as hormonal levels, psychosocial stress, smoking, sexual habits, the use of topical products or antibiotics, and the presence of urogenital infections. In this context, it has been shown that dietary habits can also affect the bacterial composition of the vaginal environment. Nevertheless, exhaustive data about the impact of dietary macronutrient intake on the composition of the vaginal environment are still lacking and many aspects remain to be fully elucidated. Similarly, the presence of several antibiotic resistance genes (ARGs) within the vaginal environment is an emerging problem, associated to incorrect antibiotic usage and awareness. Therefore, we assessed the role of macronutrient intake on the composition of the vaginal ecosystem in terms of bacterial profiles (by means of amplicon-based 16S rRNA gene profiling) and vaginal metabolite concentration in a cohort of 113 non-pregnant young women, regardless of the effect of potential confounders able to perturb per se the vaginal environment. The distribution of ARGs was similarly evaluated in relation to individual behaviours.