The microbiome and infections of the reproductive tract in human females

This talk will focus on the human vaginal microbiome and infections of the female reproductive tract. The microbiome plays key roles in human physiology and while understudied, the female reproductive tract is no exception. In women, the vaginal microbiome can fall into one of two categories, broadly speaking. The first is dominated by Lactobacillus, usually L. crispatus or L. iners. The second is a diverse microbiome containing both a wider variation in species content, as well as an overall larger number of bacteria. The latter, diverse microbiome is often found alongside other indicators of a condition called bacterial vaginosis (BV). This condition is characterized by the presence of exfoliated epithelial cells with attached bacteria, abnormally thin mucus secretions, a sharp amine odor, vaginal pH, and overgrowth of the coccobacillus, Gardnerella vaginalis. BV seems to be part of the spectrum of normal for many women, and evidence from non-human primates seems to suggest that a diverse vaginal microbiome is the ancestral state. The condition is nevertheless associated with a wide range of reproductive health complications that endanger fertility and limit reproductive success. Diverse vaginal microbiotas with Gardnerella as the major member are a unique human feature. Evidence will be presented that Gardnerella can encourage colonization and virulence of other human pathogens and suggest that sialidase could be an important factor.