Investigating the Impact of Antidepressants on Vaginal Bacteria in vitro
The vaginal microbiome, predominantly composed of Lactobacillus species, plays a critical role in maintaining vaginal health by producing lactic acid, which inhibits pathogen growth. Disruption of this balance, as seen in bacterial vaginosis (BV), is associated with increased risks of infections and adverse reproductive outcomes. Antidepressants, widely used to treat depression and anxiety, have been reported to influence microbial communities, but their impact on vaginal bacteria is not well understood. This study investigates the antibacterial activity of five antidepressants—sertraline, fluoxetine, citalopram, mirtazapine, and duloxetine—on key vaginal bacteria, including Lactobacillus jensenii, L. crispatus, L. iners, Gardnerella vaginalis, Prevotella bivia, and Fannyhessea vaginae. Minminun inhibitory concentration (MIC) assays were used, culturing bacteria under appropriate conditions and exposing them to increasing drug concentrations in a 96-well plate. Growth was assessed using optical density and visual inspection to determine MIC values.
Antidepressants demonstrated variable antibacterial activity. Gram-negative pathogens (G. vaginalis and P. bivia) exhibited higher susceptibility to sertraline, fluoxetine, and duloxetine, while Gram-positive Lactobacillus species were more resistant. Citalopram showed minimal inhibitory effects across all species, and mirtazapine had limited activity overall.
These findings suggest that antidepressants affect vaginal bacteria, with greater inhibition observed in pathogenic species. While this selective activity could mitigate conditions like BV, it may also disrupt the balance of beneficial species, particularly in individuals with existing microbiome vulnerabilities. Further studies are needed to assess clinical implications and guide microbiome-aware prescribing for better mental and vaginal health outcomes.