Oral Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

Group B Streptococcus and the vaginal microbiome: dysbiosis, co-infection, and pathogenesis of Group B Streptococcus in pregnancy (#110)

Amanda Lewis 1
  1. University of WA, Crawley, WA, Australia

Group B Streptococcus (GBS) is a common member of the vaginal microbiome that can become pathogenic during pregnancy, causing invasive infections of the uterus, placenta, and fetus. GBS is more likely to colonize women who have an abnormal vaginal microbiota characterized by low numbers of healthy lactobacilli and overgrowth of other diverse anaerobic bacteria, most often Gardnerella vaginalis. African American women are more likely to be affected by an abnormal vaginal microbiota and are also at much higher risk of having a fetus/infant affected by invasive GBS disease. We developed a mouse co-infection model to investigate the hypothesis that G. vaginalis may play a role in GBS pathogenesis during pregnancy. Briefly, 107 GBS was inoculated vaginally in the presence or absence of 107 co-infecting G. vaginalis at e14.5 in mice carrying allogeneic pregnancies. Co-infected dams were more likely to be vaginally colonized with GBS and were also more prone to developing ascending infections of uterine and placental tissue. Interestingly, co-infected animals exhibited significantly smaller placentas and evidence of placental dysfunction, a phenotype that was independent of whether animals developed ascending infection. Together, the data show that G. vaginalis encourages vaginal colonization by GBS during pregnancy and suggests that G. vaginalis may lower the threshold for GBS pathogenesis. These data suggest that further investigation into the potential influence of the vaginal microbiota on GBS disease in women is warranted.