(1) Background: Vaginal dysbiosis is strongly implicated in the pathophysiology of vaginitis and bacterial vaginosis (BV). Standard antimicrobial therapy may temporarily reduce pathogen burden but often disrupts beneficial Lactobacillus species, contributing to recurrence. Topical oxygen treatment may promote selective suppression of anaerobic pathogens and restore Lactobacillus-dominated communities. This preliminary study aimed to evaluate the effect of topical oxygen treatment—alone or adjunctive to systemic antimicrobial treatment—on vaginal microbiota composition. (2) Methods: Twenty-two symptomatic women affected by either BV or vulvovaginitis were enrolled and assigned to either topical oxygen or standard antimicrobial treatment plus topical oxygen. Oxygen delivery (3 L/min for 20 minutes, twice weekly for 2 weeks) was performed by using the Caress Flow device. Vaginal microbiota composition, pH and Lactobacillus presence were evaluated at baseline and 10–14 days post-treatment using the 16S Metagenomic Sequencing Library Preparation, sequencing and analysis. (3) Results: Topical oxygen alone increased the negative swabs from 4 (36.4%) to 9 (81.8%), p=0.06 and maintained stably high the total Lactobacillus spp. 92.60% [67.88–96.16%] at baseline and 91.50% [87.4–95.0%] pre-treatment. Oxygen plus antimicrobial treatment markedly reduced strict anaerobes (pre-treatment: 24.8% [15.3-36.5] to 9.0% [1.3-17.4] after treatment, p=0.05) and decreased BV-associated genera including Atopobium and Sneathia. Both oxygen-based regimens showed trends toward restoration or maintenance of Lactobacillus dominance. (4) Conclusions: Topical oxygen treatment favourably modulates the vaginal microbiota and may accelerate recovery from dysbiosis especially when used combined with standard antimicrobial treatment. These findings support larger trials to assess clinical efficacy and recurrence prevention.

Vaginal dysbiosis is strongly implicated in the pathophysiology of vaginitis and bacterial vaginosis (BV). Standard antimicrobial therapy may temporarily reduce pathogen burden but often disrupts beneficial Lactobacillus species, contributing to recurrence. Topical oxygen treatment may promote selective suppression of anaerobic pathogens and restore Lactobacillus-dominated communities. This preliminary study aimed to evaluate the effect of topical oxygen treatment—alone or adjunctive to systemic antimicrobial treatment—on vaginal microbiota composition. Twenty-two symptomatic women affected by either BV or vulvovaginitis were enrolled and assigned to either topical oxygen or standard antimicrobial treatment plus topical oxygen. Oxygen delivery (3 L/min for 20 min, twice weekly for 2 weeks) was performed by using the Caress Flow device. Vaginal microbiota composition, pH and Lactobacillus presence were evaluated at baseline and 10–14 days post-treatment using the 16S Metagenomic Sequencing Library Preparation, sequencing and analysis. Topical oxygen alone increased the negative swabs from 4 (36.4%) to 9 (81.8%), p = 0.06, and maintained stably high the total Lactobacillus spp., 92.60% [67.88–96.16%] at baseline and 91.50% [87.4–95.0%] pre-treatment. Oxygen plus antimicrobial treatment markedly reduced strict anaerobes (pre-treatment: 24.8% [15.3–36.5] to 9.0% [1.3–17.4] after treatment, p = 0.05) and decreased BV-associated genera including Atopobium and Sneathia. Both oxygen-based regimens showed trends toward restoration or maintenance of Lactobacillus dominance. Topical oxygen treatment favourably modulates the vaginal microbiota and may accelerate recovery from dysbiosis especially when used combined with standard antimicrobial treatment. These findings support larger trials to assess clinical efficacy and recurrence prevention.