Effects of an over-the-counter lactic-acid containing intra-vaginal douching product on the vaginal microbiota
Van der Veer C1, Bruisten SM1,2, van Houdt R3 Matser A1, van de Wijgert J4, de Vries HJC1,2,5, van der Helm JJ1
1Public Health Service, GGD, Department Infectious diseases, Amsterdam, the Netherlands;
2Amsterdam Infection & Immunity Institute, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands; 3VU University Medical Center, Department of Medical Microbiology and Infection prevention, Amsterdam, the Netherlands; 4University of Liverpool, Institute of Infection and Global Health, Liverpool, United Kingdom; 5Academic Medical Centers, Department of Dermatology, Amsterdam, the Netherlands
Background: Lactic-acid containing intra-vaginal douches are marketed as vaginal hygiene products that support optimal vaginal pH balance. We report the effect of Etos® intra-vaginal douche on the vaginal microbiota (VM).
Methods: Through advertisements 25 healthy women were recruited, aged 18-36 years, in 2015-2017. Participants were followed over 3 menstrual cycles and instructed to douche thrice weekly during cycle 2. Participants completed questionnaires at baseline, kept daily diaries to report douching, menses and sex, self-collected vaginal swabs almost daily and measured vaginal pH mid-cycle. We assessed the VM by 16SrRNA gene sequencing and tested for Candida albicans by PCR at four time-points.
Results: Participants had a median age of 24 years [IQR: 22-29], were mostly Dutch-Caucasian (88%), and 60% used combined oral contraceptives. VM was assessed for a median of 44 vaginal swabs [IQR: 41-50] per participant. At baseline, 21 participants had Lactobacillus-dominated VM (Lactobacillus crispatus (n=14), L. iners (n=6), or diverse Lactobacillus species (n=1)) and 4 participants had VM consisting of diverse anaerobes (dysbiosis). In multinomial logistic regression models, having dysbiosis was more likely in the second and third cycle, compared to the first cycle, after adjusting for menses (OR=1.4 (95% CI: 0.9-2.1) and OR=1.7 (95% CI: 0.9-3.1), respectively), though not significantly so (p=0.376). Douching did not affect vaginal pH (p=0.943). Menses increased the odds for having dysbiosis 1.7 fold (95% CI: 1.0-2.8), while douching during menses increased the odds 2.6 fold (95% CI: 1.0-6.5), compared to not menstruating (p=0.099). Participants were more likely to test positive for C. albicans after cycle two, compared to cycle one (OR = 3.0 (95% CI: 1.2 - 7.2); p=0.017).
Conclusion: Etos® lactic-acid intra-vaginal douche did not significantly affect the VM composition or vaginal pH, but increased odds for vaginal dysbiosis was observed, especially when douching during menses. Furthermore, douching may promote C. albicans infections.