Metagenome Profiling of Anterior Uterine Samples to Improve in-vitro Fertilization Success Ratio

Abstract

Background: The radical increase in the number of couples experiencing infertility, which is the inability to conceive in a natural manner, has increased the interest among the researchers worldwide to identify the root cause for this problem. Relevant studies are needed to ascertain the cause behind unexplained infertility, and certain interventions are needed in the process of assisted reproductive technology to improve the implantation success. The presence of certain pathogenic flora in the cervix and vaginal region are often attributed to the failure of In-vitro fertilization (IVF), which is a method of assisted reproduction. This study explored the cervix and vaginal microbiota of 52 such infertile females who underwent assisted reproduction (IVF), to analyse the microbiota, identify pathogenic flora and evaluate the diversity of the flora.Methods: 52 microbial swab samples of infertile females were sequenced using 16s rRNA approach. 16s rRNA data analysis was performed to get the taxonomic abundance and pathogenicity of the resultant microbiota. The microbial communities were statistically assessed for probable similarities and differences between positive, negative and not applicable outcomes of IVF.Results: A total of 31 genera were identified across the study samples, and a thorough investigation of associated pathogenicity of these taxa was performed. Certain pathogenic genera specific to positive as well as negative implantation were observed. Additionally, the alpha diversity was observed to be higher in the cervical region compared to the vaginal region. Rarefaction analysis was performed. The analysis of beta diversity was performed and the phylogenetic distance was visualized through distance boxplots. Conclusion: The presence of pathogenic bacteria, especially those associated with conditions like Bacterial Vaginosis and Chronic Endometritis, are often linked to infertility conditions and were predominant in the cervical and vaginal samples. Dysbiosis in the cervical and vaginal region is often attributed to decrease in Lactobacillus spp. and increase in other species, leading to difference in functionalities and growth of pathogens. In this study, the presence of pathogenic organisms in both regions was remarkable. Additionally, large bacterial diversity in cervical regions was observed, which might be a possible reason for implantation failure. Further studies on the mechanism of action of these bacteria is needed; the possible sources of contamination, such as the tip of the catheter during embryo transfer, the DNA extraction kits prior to sequencing, etc. need to be identified as this might introduce pathogens during the procedure. By using more sterility in the procedure as well as profiling the metagenome of the infertile female, novel insights can be gained as well as a more directed procedure can be performed to increase the chances of success in implantation.