Abstract
Here, we present a longitudinal shotgun sequencing metagenomics study of 16 healthy, Danish women in the reproductive age. The aim of the study was to investigate whether lactobacilli, orally consumed, had any impact on the vaginal microbiome and its functional potential. The 16 women aged 19-45 years were recruited from Copenhagen, Denmark. One baseline vaginal sample (Day 0) and two study samples (Days 25-30 and Days 55-60, respectively), were sampled. The vaginal samples were analyzed by shotgun metagenomics. We detected 26 species in the vaginal microbiota of the 16 women, of which six belonged to the Lactobacillus genus. We observed three vaginal microbiome clusters mainly dominated by Gardnerella vaginalis, Lactobacillus iners, or Lactobacillus crispatus. The oral probiotic had no detectable effect on either the composition or the functional potential of the vaginal microbiota. Most of the study subjects (11 out of 16 women) exhibited only minor changes in the vaginal microbiome during the treatment with probiotics. Any compositional changes could not be associated to the probiotic treatment. Future studies may benefit from an increased number of participants, and administration of the probiotics during conditions with bacterial imbalance (e.g., during/after antibiotic treatment) or the use of different Lactobacillus spp. known to colonize the vagina.