Dataset Information

Isolation of Vaginal Lactobacilli and Characterization of Anti-Candida Activity.

ABSTRACT: Healthy vaginal microbiota is dominated by Lactobacillus spp., which form a critical line of defence against pathogens, including Candida spp. The present study aims to identify vaginal lactobacilli exerting in vitro activity against Candida spp. and to characterize their antifungal mechanisms of action. Lactobacillus strains were isolated from vaginal swabs of healthy premenopausal women. The isolates were taxonomically identified to species level (L. crispatus B1-BC8, L. gasseri BC9-BC14 and L. vaginalis BC15-BC17) by sequencing the 16S rRNA genes. All strains produced hydrogen peroxide and lactate. Fungistatic and fungicidal activities against C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis and C. lusitaniae were evaluated by broth micro-dilution method. The broadest spectrum of activity was observed for L. crispatus BC1, BC4, BC5 and L. vaginalis BC15, demonstrating fungicidal activity against all isolates of C. albicans and C. lusitaniae. Metabolic profiles of lactobacilli supernatants were studied by 1H-NMR analysis. Metabolome was found to be correlated with both taxonomy and activity score. Exclusion, competition and displacement experiments were carried out to investigate the interference exerted by lactobacilli toward the yeast adhesion to HeLa cells. Most Lactobacillus strains significantly reduced C. albicans adhesion through all mechanisms. In particular, L. crispatus BC2, L. gasseri BC10 and L. gasseri BC11 appeared to be the most active strains in reducing pathogen adhesion, as their effects were mediated by both cells and supernatants. Inhibition of histone deacetylases was hypothesised to support the antifungal activity of vaginal lactobacilli. Our results are prerequisites for the development of new therapeutic agents based on probiotics for prophylaxis and adjuvant therapy of Candida infection.

SUBMITTER: Parolin C

PROVIDER: S-EPMC4476673 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Isolation of Vaginal Lactobacilli and Characterization of Anti-Candida Activity.

Parolin Carola C Marangoni Antonella A Laghi Luca L Foschi Claudio C Ñahui Palomino Rogers Alberto RA Calonghi Natalia N Cevenini Roberto R Vitali Beatrice B

PloS one 20150622 6

Healthy vaginal microbiota is dominated by Lactobacillus spp., which form a critical line of defence against pathogens, including Candida spp. The present study aims to identify vaginal lactobacilli exerting in vitro activity against Candida spp. and to characterize their antifungal mechanisms of action. Lactobacillus strains were isolated from vaginal swabs of healthy premenopausal women. The isolates were taxonomically identified to species level (L. crispatus B1-BC8, L. gasseri BC9-BC14 and L ...[more]

PMID: 26098675

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Project description:The human vaginal microbiome is dominated by bacteria from the genus Lactobacillus, which create an acidic environment thought to protect women against sexually transmitted pathogens and opportunistic infections. Strikingly, lactobacilli dominance appears to be unique to humans; while the relative abundance of lactobacilli in the human vagina is typically >70%, in other mammals lactobacilli rarely comprise more than 1% of vaginal microbiota. Several hypotheses have been proposed to explain humans' unique vaginal microbiota, including humans' distinct reproductive physiology, high risk of STDs, and high risk of microbial complications linked to pregnancy and birth. Here, we test these hypotheses using comparative data on vaginal pH and the relative abundance of lactobacilli in 26 mammalian species and 50 studies (N = 21 mammals for pH and 14 mammals for lactobacilli relative abundance). We found that non-human mammals, like humans, exhibit the lowest vaginal pH during the period of highest estrogen. However, the vaginal pH of non-human mammals is never as low as is typical for humans (median vaginal pH in humans = 4.5; range of pH across all 21 non-human mammals = 5.4-7.8). Contrary to disease and obstetric risk hypotheses, we found no significant relationship between vaginal pH or lactobacilli relative abundance and multiple metrics of STD or birth injury risk (P-values ranged from 0.13 to 0.99). Given the lack of evidence for these hypotheses, we discuss two alternative explanations: the common function hypothesis and a novel hypothesis related to the diet of agricultural humans. Specifically, with regard to diet we propose that high levels of starch in human diets have led to increased levels of glycogen in the vaginal tract, which, in turn, promotes the proliferation of lactobacilli. If true, human diet may have paved the way for a novel, protective microbiome in human vaginal tracts. Overall, our results highlight the need for continuing research on non-human vaginal microbial communities and the importance of investigating both the physiological mechanisms and the broad evolutionary processes underlying human lactobacilli dominance.

Project description:BACKGROUND: Bacterial vaginosis (BV), which is highly prevalent in the African population, is one of the most common vaginal syndromes affecting women in their reproductive age placing them at increased risk for sexually transmitted diseases including infection by human immunodeficiency virus-1. The vaginal microbiota of a healthy woman is often dominated by the species belonging to the genus Lactobacillus namely L. crispatus, L. gasseri, L. jensenii and L. iners, which have been extensively studied in European populations, albeit less so in South African women. In this study, we have therefore identified the vaginal Lactobacillus species in a group of 40 African women from Soweto, a township on the outskirts of Johannesburg, South Africa. METHODS: Identification was done by cultivating the lactobacilli on Rogosa agar, de Man-Rogosa-Sharpe (MRS) and Blood agar plates with 5% horse blood followed by sequencing of the 16S ribosomal DNA. BV was diagnosed on the basis of Nugent scores. Since some of the previous studies have shown that the lack of vaginal hydrogen peroxide (H2O2) producing lactobacilli is associated with bacterial vaginosis, the Lactobacillus isolates were also characterised for their production of H2O2. RESULTS: Cultivable Lactobacillus species were identified in 19 out of 21 women without BV, in three out of five women with intermediate microbiota and in eight out of 14 women with BV. We observed that L. crispatus, L. iners, L. jensenii, L. gasseri and L. vaginalis were the predominant species. The presence of L. crispatus was associated with normal vaginal microbiota (P = 0.024). High level of H2O2 producing lactobacilli were more often isolated from women with normal microbiota than from the women with BV, although not to a statistically significant degree (P = 0.064). CONCLUSION: The vaginal Lactobacillus species isolated from the cohort of South African women are similar to those identified in European populations. In accordance with the other published studies, L. crispatus is related to a normal vaginal microbiota. Hydrogen peroxide production was not significantly associated to the BV status which could be attributed to the limited number of samples or to other antimicrobial factors that might be involved.

Dataset Information

Isolation of Vaginal Lactobacilli and Characterization of Anti-Candida Activity.

Publications

Isolation of Vaginal Lactobacilli and Characterization of Anti-Candida Activity.

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