Vaginal pH measured in vivo: lactobacilli determine pH and lactic acid concentration
PublisherBioMed Central Ltd.
MetadataShow full item record
AbstractBackground: Lactic acid (protonated lactate) has broad antimicrobial activity. Vaginal lactobacilli produce lactic acid, and are known to confer protection against reproductive tract infections when they are predominant in the vaginal microbiota. Using novel ex vivo methods, we showed that cervicovaginal fluid (CVF) from women with a predominantly lactobacilli-morphotype microbiota contains significantly more lactic acid than previously thought, sufficient to inactivate reproductive tract pathogens. Here, we measured vaginal pH in vivo in 20 women with a predominantly lactobacilli-morphotype (low Nugent score) microbiota. We also investigated the in vitro production of protons (as hydrogen ions) and lactate by vaginal lactobacilli. Results: The average vaginal pH in these women was 3.80 ± 0.20, and the average lactate concentration was 0.79% ± 0.22% w/v, with pH and lactate concentration tightly correlated for each sample. In vitro, lactobacilli cultured from these CVF samples reached an average pH of 3.92 ± 0.22, but the average lactate concentration was only 0.14% ± 0.06% w/v, approximately five-fold less than in the corresponding CVF samples. When the pH of the cultures was raised, lactate and hydrogen ion production resumed, indicating that production of lactate and hydrogen ions by vaginal lactobacilli is limited primarily by their sensitivity to hydrogen ion concentration (low pH) not lactate concentration. Conclusions: Some vaginal lactobacilli cultures have a lower limiting pH than others, and limiting pHs in vitro showed good correlation with pHs measured in vivo. The limiting pH of the lactobacilli predominant in a woman's vaginal microbiota seems critical in determining the concentration of antimicrobial lactic acid protecting her. © 2019 The Author(s).
Identifier to cite or link to this itemhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85059934425&doi=10.1186%2fs12866-019-1388-8&partnerID=40&md5=bcfe6ecd36522ef22b71fd1863db3729; http://hdl.handle.net/10713/8551
- Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
- Authors: O'Hanlon DE, Moench TR, Cone RA
- Issue date: 2013
- Vaginal microbiome.
- Authors: Buchta V
- Issue date: Winter 2018
- Anti-HIV-1 Activity of Lactic Acid in Human Cervicovaginal Fluid.
- Authors: Tyssen D, Wang YY, Hayward JA, Agius PA, DeLong K, Aldunate M, Ravel J, Moench TR, Cone RA, Tachedjian G
- Issue date: 2018 Jul 5
- Distinct Immune Responses Elicited From Cervicovaginal Epithelial Cells by Lactic Acid and Short Chain Fatty Acids Associated With Optimal and Non-optimal Vaginal Microbiota.
- Authors: Delgado-Diaz DJ, Tyssen D, Hayward JA, Gugasyan R, Hearps AC, Tachedjian G
- Issue date: 2019
- Metabolic properties of lactobacilli in women experiencing recurring episodes of bacterial vaginosis with vaginal pH >or= 5.
- Authors: Garg KB, Ganguli I, Kriplani A, Lohiya NK, Thulkar J, Talwar GP
- Issue date: 2010 Jan