Introduction The human microbiota plays important roles in immune system development and resistance to infection. However, factors that influence vaginal bacterial community composition and dynamics are not well understood. There have been conflicting reports of altered vaginal microbiota and infection susceptibility with contraception use. The objective of this study was to determine if contraception use altered the vaginal microbiota.
Methods Vaginal swab samples were obtained from over 400 women during their first year of using hormonal contraception (levonorgestrel intrauterine system (LNG-IUS), depot medroxyprogesterone acetate (DMPA), combined oral contraceptive, contraceptive patch and etonogestrel implant) or a non-hormonal copper intrauterine device. Samples were obtained at baseline, 6 months and 12 months as part of the Contraceptive CHOICE study. The V4 region of the bacterial 16S rRNA-encoding gene was amplified from the vaginal swab DNA and sequenced with an Illumina MiSeq. The 16S rRNA gene sequences were processed and analysed using the software package mothur. After clustering the sequences into operational taxonomic units (OTUs) based on sequence similarity we calculated several ecological metrics including θYC distances (a metric that takes relative abundances of both shared and non-shared OTUs into account) between communities.
Results The vaginal microbiota in this study clustered into 3 major vaginal bacterial community types: one dominated by Lactobacillus iners, one dominated by Lactobacillus crispatus and one more diverse community type. Initial analysis indicates differences between the microbiota at baseline and after LNG-IUS use.
Additionally, specific OTUs were enriched with the use of certain contraceptive methods. For example, higher levels of 2 Prevotella OTUs were associated with DMPA use.
Conclusion Alterations of the vaginal microbiota are associated with the use of certain contraceptives. Further studies and analysis will be needed to verify these findings and determine the implications for infection susceptibility.
Disclosure of interest statement We did not receive any commercial contributions for this study.