Association of the eukaryotic vaginal virome with prophylactic antibiotic exposure and reproductive outcomes in a subfertile population undergoing in vitro fertilisation: a prospective exploratory study

Abstract

Objective: The objective of this study was to use high-throughput sequencing to describe the vaginal eukaryotic DNA virome in patients undergoing in vitro fertilisation (IVF) to examine associations between the vaginal virome, antibiotic exposure and IVF outcomes.

Design: Prospective exploratory study.

Setting: Single academic fertility centre.

Population: Subfertile women age 18-43 years undergoing their first IVF cycle with a fresh embryo transfer.

Methods: The primary exposure was prophylactic azithromycin or no azithromycin before IVF. A mid-vaginal swab was obtained at the time of embryo transfer for virome analysis.

Main outcome measures: The primary outcomes compared between exposure groups were characteristics of vaginal virome and clinical pregnancy rates. Secondary outcomes were virome associations with number of oocytes retrieved, number of blastocysts and implantation rate.

Results: Twenty-six women contributed a vaginal swab before embryo transfer. There were no significant differences in IVF outcomes between azithromycin groups. There was no association between viral diversity and clinical pregnancy overall. A higher diversity of herpesviruses and α-papillomaviruses was observed in samples from the azithromycin-treated group compared with the no azithromycin group (P = 0.04). In women that received azithromycin, viral diversity was higher in the group that did not achieve clinical pregnancy compared with those who did (P = 0.06).

Conclusions: We demonstrate that the vaginal eukaryotic virome in women undergoing IVF is associated with antibiotic exposure. Additionally, we demonstrate an inverse trend between viral diversity and pregnancy, with a higher number of viruses detected associated with failure to achieve clinical pregnancy in the azithromycin group.

Tweetable abstract: Higher viral diversity is associated with prophylactic antibiotic exposure in subfertile women undergoing IVF.

Keywords: Embryo transfer; in vitro fertilisation; reproductive tract microbiome; vaginal virus; virome.

Figure1:

The vaginal virome in IVF patients at the time of embryo transfer. The viruses detected in each sample are shown. Each patient is represented in a row. Each virus detected is indicated in a column. The dark bars indicate the presence of the virus in the sample. Samples are grouped according to whether clinical pregnancy was achieved and according to whether they were included in the prophylactic azithromycin or no azithromycin groups of the study. HSV, herpes simplex virus. EBV, Epstein Barr virus. HHV, human herpes virus. MCPy, Merkel cell polyomavirus. HPV, human papillomavirus.

Figure2:

Associations between viral diversity with pregnancy or azithromycin prophylaxis. In panels A (all viruses) and B (herpesviruses and alphapapillomaviruses), viral diversity (total number of different viruses detected) in each sample are plotted using box and whisker plots, and pregnancy outcome are compared. The median is indicated by a horizontal line, the quartiles indicated by boxes, and minimum and maximum by the whiskers (outliers excluded). In panels C (all viruses) and D (the number of different alphapapillomaviruses and herpesviruses detected) are plotted using box and whisker plots, and azithromycin groups are compared.

Figure3:

Associations between viral diversity and clinical characteristics with pregnancy and azithromycin prophylaxis. AMH levels (panel A), peak estradiol levels (panel B), viral diversity (the total number of viruses detected) (panel C), and number of alphapapillomaviruses and herpesviruses (panel D) are plotted using box and whisker plots, and groups are compared.