The human vaginal microbial community.

Monopolization of the vaginal econiche by a limited number of Lactobacillus species, resulting in low pH of 3.5-4.5, has been shown to protect women against vaginal dysbiosis, sexually transmitted infections and adverse pregnancy outcomes. Still, controversy exists as to which characteristics of lactobacilli are most important with regard to colonization resistance and to providing protection. This review addresses the antimicrobial and anti-inflammatory roles of lactic acid (and low pH) and hydrogen peroxide (and oxidative stress) as means of lactobacilli to dominate the vaginal econiche.