Therefore the normal vaginal secretions are a heterogeneous suspension of vaginal epithelial cells and lactobacilli in fluid that emanates from the cervix and vaginal walls ( Fig.
3 Loss of the normal Lactobacillus-dominated vaginal microbiota increases the likelihood of exogenous infection after exposure to sexually transmitted pathogens, 4 as well as the risk for endogenous infection in association with pregnancy and gynecologic surgery. In addition to producing lactic acid, lactobacilli may also produce hydrogen peroxide, which is bactericidal alone and highly bactericidal in combination with physiologic amounts of myeloperoxidase and chloride. Indeed, the predominant cells in the vaginal secretions of most normal women are lactobacilli and vaginal epithelial cells ( Fig. The vagina is not sterile, and many species of bacteria can be isolated from vaginal specimens from healthy women, including Prevotella, Megasphaera, Gardnerella, and Atopobium spp., but lactobacilli usually dominate the vaginal microbiota. In addition, blacks and Hispanics had higher mean vaginal pH levels than whites and Asians. jensenii and those with higher proportions of strictly anaerobic bacteria had higher mean pH levels than the other groups. In the studies of Ravel and associates 2 the vaginal communities of women whose microbiota was dominated by L. Lactobacilli metabolize glucose to lactic acid, which results in a normal vaginal pH of about 4.0. Data reported by Ravel and associates 2 demonstrated that the vaginal bacterial communities of asymptomatic North American women clustered into five groups: four were dominated by Lactobacillus crispatus, Lactobacillus jensenii, Lactobacillus iners, or Lactobacillus gasseri, whereas the fifth had lower proportions of lactobacilli and higher proportions of strictly anaerobic organisms. As the cells autolyze, glycogen depolymerizes to glucose, which serves as an energy source for bacteria known as lactobacilli. Vaginal cells contain glycogen and are continually shed into the lumen of the vagina. The normal vaginal secretions are a physiologically important biomass. Bennett MD, in Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 2020 Vaginal Secretions
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