Introduction Of female visitors to the STI clinic in Amsterdam, 31% report use of vaginal cleansing products (including douches). Vaginal douching may negatively affect vaginal microbiota compositions (VM). We report the effect of intra-vaginal douching on the VM in a prospective study.
Methods Through advertisements, we recruited 25 healthy women, aged 18–36 years, from 2015–2016. Participants were followed over 3 menstrual cycles and were instructed to use an intra-vaginal lactic-acid-containing douche 3 times a week during the 2nd cycle. Participants self-collected a median of 68 [IQR: 64–68] vaginal swabs. Baseline characteristics were collected through questionnaires. All participants kept a daily diary in which they reported douching, menstruation, sexual activity, etc. VM were assessed by 16S rRNA (V3-V4 region) sequencing. Associations between douching and VM were assessed by multivariable logistic regression, using generalised estimating equations to account for multiple observations within the same individual.
Results As of December 2016, a median of 42 [IQR:40–44] vaginal swabs from 10/25 women were analysed. These 10 women had a median age of 25 years [IQR: 21.8–29.3], 9 women were Dutch-Caucasian, 9 used hormonal contraceptives and all were highly educated. At baseline, 8 women had lactobacilli-dominated VM (Lactobacillus crispatus (n=6), L. iners (n=1) or L. iners/L. jensenii (n=1)) and 2 women had polybacterial Gardnerella vaginalis-containing VM (GV-VM). The latter 2 women continued to have GV-VM throughout the study period. The VMs of 2 women, dominated either by L. crispatus or L. iners at baseline, shifted to GV-VM during the 2nd cycle, which persisted in the 3rd cycle. Having GV-VM was more likely in the 2nd and 3rd cycle, compared to the 1 st cycle, after adjusting for sex and menses (odds ratio (OR)=1.7 (95% CI: 0.9–3.1) and OR=2.1 (95% CI: 0.7–6.1), respectively), though not statistically significanctly so.
Conclusion Our interim analyses suggest that regular intra-vaginal douching may promote a shift from lactobacilli-dominated VM to GV-VM.