Lactobacillus crispatus-dominated vaginal microbiome and Acinetobacter-dominated seminal microbiome support beneficial ART outcome.

Introduction: Despite the considerable progress made in assisted reproductive technologies (ART), the implantation rate of transferred embryos remains low and in many cases, the reasons for failure remain unclear. We aimed to determine the potential impact of female and male partners' reproductive tract microbiome composition on ART outcome.

Material And Methods: The ART couples (n = 97) and healthy couples (n = 12) were recruited into the study. The smaller healthy group underwent a careful selection according to their reproductive and general health criteria. Both vaginal and semen samples were subjected to 16S rDNA sequencing to reveal the bacterial diversity and identify distinct microbial community types. Ethics statement The study was approved by the Ethics Review Committee on Human Research of Tartu University, Tartu, Estonia (protocol no. 193/T-16) on 31 May 2010. Participation in the research was voluntary. Written informed consent was obtained from all study participants.

Results: The men with Acinetobacter-associated community who had children in the past, had the highest ART success rate (P < 0.05). The women with bacterial vaginosis vaginal microbiome community and with L. iners-predominant and L. gasseri-predominant microbiome had a lower ART success rate than women with the L. crispatus-predominant or the mixed lactic-acid-bacteria-predominant type (P < 0.05). The 15 couples where both partners had beneficial microbiome types had a superior ART success rate of 53%, when compared with the rest of the couples (25%; P = 0.023).

Conclusions: Microbiome disturbances in the genital tract of both partners tend to be associated with couple's infertility as well as lower ART success levels and may thus need attention before the ART procedure. The incorporation of genitourinary microbial screening as a part of the diagnostic evaluation process may become routine for ART patients if our results are confirmed by other studies.