Infertile couples undergoing the use of assisted reproductive technology are a good study model to evaluate the microbiological signatures affecting reproductive health. We tested vaginal lavages, follicular fluids, embryo culture mediums, and seminal fluids from 47 couples for their microbiome composition and
HPV infection. Twenty-five infertile couples were diagnosed with unexplained
infertility, whereas 22 were diagnosed with explained
infertility. Lactobacilli were dominant in the vaginal lavages of both patient groups, and the most abundant species was L. iners (CST III), which is linked to a decreased fertility rate. Besides this, L. gasseri-which is known to be associated with oocyte DNA fragmentation and decreased sperm mobility-was identified in the seminal fluids, follicular fluids, and embryo
culture media of the unexplained
infertility group. Prevotella was increased in the seminal fluids of the explained
infertility group, along with HPV-positive seminal fluids: an
infection commonly associated with
infertility, especially
male infertility. Prevotella has been described to negatively affect sperm motility. Taken together, these results suggest that the profiling of the reproductive tract microbiome can add new perspectives to human reproduction.