Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.

Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to ex...

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Autores principales:	Deirdre E O'Hanlon, Thomas R Moench, Richard A Cone
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/cbc296ac7c154489bb9b97b95935f99d
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spelling	oai:doaj.org-article:cbc296ac7c154489bb9b97b95935f99d2021-11-18T08:48:01ZVaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.1932-620310.1371/journal.pone.0080074https://doaj.org/article/cbc296ac7c154489bb9b97b95935f99d2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24223212/?tool=EBIhttps://doaj.org/toc/1932-6203Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.Deirdre E O'HanlonThomas R MoenchRichard A ConePublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 11, p e80074 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Deirdre E O'Hanlon Thomas R Moench Richard A Cone Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
description	Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.
format	article
author	Deirdre E O'Hanlon Thomas R Moench Richard A Cone
author_facet	Deirdre E O'Hanlon Thomas R Moench Richard A Cone
author_sort	Deirdre E O'Hanlon
title	Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
title_short	Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
title_full	Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
title_fullStr	Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
title_full_unstemmed	Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.
title_sort	vaginal ph and microbicidal lactic acid when lactobacilli dominate the microbiota.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/cbc296ac7c154489bb9b97b95935f99d
work_keys_str_mv	AT deirdreeohanlon vaginalphandmicrobicidallacticacidwhenlactobacillidominatethemicrobiota AT thomasrmoench vaginalphandmicrobicidallacticacidwhenlactobacillidominatethemicrobiota AT richardacone vaginalphandmicrobicidallacticacidwhenlactobacillidominatethemicrobiota
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Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.

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