The influence of sexual activity on the vaginal microbiota and Gardnerella vaginalis clade diversity in young women

PLoS One. 2017 Feb 24;12(2):e0171856. doi: 10.1371/journal.pone.0171856. eCollection 2017.


Objectives: To examine the influence of sexual activity on the composition and consistency of the vaginal microbiota over time, and distribution of Gardnerella vaginalis clades in young women.

Methods: Fifty-two participants from a university cohort were selected. Vaginal swabs were self-collected every 3-months for up to 12 months with 184 specimens analysed. The vaginal microbiota was characterised using Roche 454 V3/4 region 16S rRNA sequencing, and G.vaginalis clade typing by qPCR.

Results: A Lactobacillus crispatus dominated vaginal microbiota was associated with Caucasian ethnicity (adjusted relative risk ratio[ARRR] = 7.28, 95%CI:1.37,38.57,p = 0.020). An L.iners (ARRR = 17.51, 95%CI:2.18,140.33,p = 0.007) or G.vaginalis (ARRR = 14.03, 95%CI:1.22,160.69, p = 0.034) dominated microbiota was associated with engaging in penile-vaginal sex. Microbiota dominated by L.crispatus, L.iners or other lactobacilli exhibited greater longitudinal consistency of the bacterial communities present compared to ones dominated by heterogeneous non-lactobacilli (p<0.030); sexual activity did not influence consistency. Women who developed BV were more likely to have clade GV4 compared to those reporting no sex/practiced non-coital activities (OR = 11.82, 95%CI:1.87,74.82,p = 0.009). Specimens were more likely to contain multiple G.vaginalis clades rather than a single clade if women engaged in penile-vaginal sex (RRR = 9.55, 95%CI:1.33,68.38,p = 0.025) or were diagnosed with BV (RRR = 31.5, 95%CI:1.69,586.87,p = 0.021).

Conclusions: Sexual activity and ethnicity influenced the composition of the vaginal microbiota of these young, relatively sexually inexperienced women. Women had consistent vaginal microbiota over time if lactobacilli were the dominant spp. present. Penile-vaginal sex did not alter the consistency of microbial communities but increased G.vaginalis clade diversity in young women with and without BV, suggesting sexual transmission of commensal and potentially pathogenic clades.

MeSH terms

  • Adolescent
  • Asian People
  • Australia
  • Biodiversity
  • Coitus / physiology
  • Female
  • Gardnerella vaginalis / classification
  • Gardnerella vaginalis / genetics*
  • Gardnerella vaginalis / isolation & purification
  • Humans
  • Lactobacillus / classification
  • Lactobacillus / genetics*
  • Lactobacillus / isolation & purification
  • Longitudinal Studies
  • Male
  • Microbiota / genetics*
  • Phylogeny
  • RNA, Ribosomal, 16S / genetics*
  • Vagina / microbiology*
  • Vaginosis, Bacterial / diagnosis
  • Vaginosis, Bacterial / ethnology
  • Vaginosis, Bacterial / microbiology
  • White People
  • Young Adult


  • RNA, Ribosomal, 16S

Grant support

The research presented was funded by the National Health and Medical Research Council of Australia (APP1020457).