Pathogenesis Of Bacterial Vaginosis Research Articles

Veillonellaceae family members uniquely alter the cervical metabolic microenvironment in a human three-dimensional epithelial model

Bacterial vaginosis (BV) is a gynecologic disorder characterized by a shift in cervicovaginal microbiota from Lactobacillus spp. dominance to a polymicrobial biofilm composed of diverse anaerobes. We utilized a well-characterized human three-dimensional cervical epithelial cell model in conjunction with untargeted metabolomics and immunoproteomics analyses to determine the immunometabolic contribution of three members of the Veillonellaceae family: Veillonella atypica, Veillonella montpellierensis and Megasphaera micronuciformis at this site. We found that Veillonella spp. infections induced significant elevation of polyamines. M. micronuciformis infections significantly increased soluble inflammatory mediators, induced moderate levels of cell cytotoxicity, and accumulation of cell membrane lipids relative to Veillonella spp. Notably, both V. atypica and V. montpellierensis infections resulted in consumption of lactate, a key metabolite linked to gynecologic and reproductive health. Collectively our approach and data provide unique insights into the specific contributions of Veillonellaceae members to the pathogenesis of BV and women’s health.

Features of vaginal microbiocenosis in women of reproductive age with overweight and obesity

Overweight and obesity play a negative role in gynecological and obstetric practicE.In women, the frequency of infectious pathology increases against the background of metabolic disorderS.The most common form of infectious vaginitis is bacterial urogenital candidiasis, in the etiological structure of which a significant role belongs to the fungi Candida albicans, as well as Candida non-albicans: C.glabrata, C.tropicalis, C.parapsilosis, C.krusei. Associations of Candida fungi with various representatives of opportunistic microflora, such as gram-positive and gram-negative aerobic, facultative-anaerobic and obligate-anaerobic microorganisms, are often formed. As a result, numerous bacterial pathogens multiply and the number of lactobacilli, which are usually part of the bacterial flora of the vagina, is significantly reduced. In bacterial vaginosis (BV), the concentration of anaerobic pathogens Peptostreptococcus sp, Gardnerella vaginalis, Peptostreptococcus Mobiluncus sp, Mycoplasma hominis can increase 100 timeS.Activation of Atopobium vaginae and Gardnerella vaginalis, which play a “key” role in the pathogenesis of BV, has been proven. The aim of the study was to study changes in the vaginal microbiome in women with candidiasis and bacterial vaginosis in order to improve existing treatment regimenS.We examined 120 women of reproductive age with overweight and obesity. The degree of microbial contamination was determined and the maximum possible spectrum of aerobic and facultative-anaerobic microflora was detected. In women with vulvovaginal candidiasis, overweight and obesity, a high concentration (lg5.8 CFU/ml) of Candida fungi was found, and in 95% of patients two-, three- and four-component associations of Candida fungi with various representatives of conditional pathogenic microflora. Lactobacillus deficiency was found in 58.3% of patients, and their complete absence – in 10.0%. Bacteriological examination of the vaginal contents of women with vaginosis and obesity revealed significant dysbiotic disorders of the vaginal microflora, three-, four- and even five-component associations of anaerobic and facultative anaerobic microflora with a predominance of anaerobeS.A low seeding level of lactobacilli (lg2.2 CFU/ml) was established. Thus, the gram-positive anaerobic and facultative anaerobic microflora of Firmicutes have a significant share in the spectrum of vaginal microflora in overweight and obese patients, in contrast to non-obese women of reproductive agE.In women of reproductive age with vulvovaginal candidiasis and obesity, in contrast to non-obese patients, a higher frequency of fungal-bacterial associations, a higher quantitative level of vaginal contamination by Candida albicans and non-albicans with a lack or general absence of lactoflora.

Asymptomatic Bacterial Vaginosis: To Treat or Not to Treat?

The purpose of this review is to summarize current evidence for and against the treatment of asymptomatic bacterial vaginosis (BV) in women. Asymptomatic BV is common although its pathogenesis remains incompletely understood. In favor of treating asymptomatic BV is the large body of data supporting that it is sexually transmitted. Along these lines and similar to other STIs, treatment of BV, regardless of symptom status, should be considered to reduce adverse outcomes of infection (i.e. adverse birth outcomes, infertility, post-gynecologic surgery infections, etc.) and prevent further sexual transmission of BV pathogen(s) to sexual partners. One study has found that treatment of women with asymptomatic BV led to a significant reduction in incident chlamydial infections over a 6 month follow-up period, compared to observation-only women. Additionally, some women with asymptomatic BV actually have symptomatic BV but do not recognize these symptoms as an infection. Nevertheless, limitations of the trial regarding treatment of asymptomatic BV as well as the 2020 United States Preventative Task Force recommendation against screening and treatment of asymptomatic BV in pregnant women dampen enthusiasm for recommending treatment in this setting. Treatment of asymptomatic BV remains controversial. Additional studies are needed to further investigate the pathogenesis of BV, which will directly influence advances in its diagnosis, treatment, and prevention.

Analysis of CRISPR-Cas systems in Gardnerella suggests its potential role in the mechanisms of bacterial vaginosis

Bacterial vaginosis (BV) is the principal cause of vaginal discharge among women, and it can lead to many comorbidities with a negative impact in women’s daily activities. Despite the fact that the pathophysiological process of BV remains unclear, great advances had been achieved in determining consequences of the shift in the vaginal community, and it was defined that Gardnerella spp., plays a key role in the pathogenesis of BV. Interactions of vaginal phage communities and bacterial hosts may be relevant in eubiosis/dysbiosis states, so defense mechanisms in Gardnerella spp., against phage infections could be relevant in BV development. In this study, we analyzed CRISPR-Cas systems among the 13 Gardnerella species recently classified, considering that these systems act as prokaryotic immune systems against phages, plasmids, and other mobile genetic elements. In silico analyses for CRISPR-Cas systems mining over the 81 Gardnerella spp., strains genomes analyzed led to the identification of subtypes I-E and II-C. Spacers analyses showed a hypervariable region across species, providing a high resolution level in order to distinguish clonality in strains, which was supported with phylogenomic analyses based on Virtual Genomic Fingerprinting. Moreover, most of the spacers revealed interactions between Gardnerella spp., strains and prophages over the genus. Furthermore, virulence traits of the 13 species showed insights of potential niche specificity in the vaginal microbiome. Overall, our results suggest that the CRISPR-Cas systems in the genus Gardnerella may play an important role in the mechanisms of the development and maintenance of BV, considering that the Gardnerella species occupies different niches in the vaginal community; in addition, spacer sequences can be used for genotyping studies.

Risk and protective factors associated with BV chronicity among women in Rakai, Uganda

ObjectivesTo assess risk and protective factors associated with bacterial vaginosis (BV) chronicity ascertained by Nugent score criteria.MethodsA longitudinal cohort study included 255 sexually experienced, postmenarcheal women who provided weekly self-collected...

The Vaginal Microbiota Among Adolescent Girls in Tanzania Around the Time of Sexual Debut.

The aetiology of bacterial vaginosis (BV) is not well-understood, and prevalence appears to be higher among women living in sub-Saharan Africa. A recent conceptual model implicates three main bacteria (Gardnerella vaginalis; Atopobium vaginae; and Prevotella bivia), sexual activity, sialidase activity, and biofilm formation in the pathogenesis of BV. We describe the vaginal microbiota, presence of the putative sialidase A gene of G. vaginalis, and biofilm among 386 adolescent girls aged 17 and 18 years in a cross-sectional study in Mwanza, Tanzania around the time of expected sexual debut. Vaginal swabs were collected and tested by quantitative polymerase chain reaction (qPCR) for five Lactobacillus species, G. vaginalis, A. vaginae, P. bivia, the sialidase A gene of G. vaginalis, and by fluorescence in situ hybridisation (FISH) for evidence of G. vaginalis and A. vaginae biofilm. We conducted a risk factor analysis of G. vaginalis, A. vaginae and P. bivia, and explored the associations between biofilm, the presence of the sialidase A gene, and non-optimal vaginal microbiota (Nugent 4–7). L. crispatus and L. iners were detected in 69 and 82% of girls, respectively. The prevalence of L. crispatus was higher than previously reported in earlier studies among East and Southern African women. G. vaginalis, A. vaginae, P. bivia were independently associated with reported penile-vaginal sex. Samples with all three BV-associated bacteria made up the highest proportion of samples with Nugent-BV compared to samples with each bacterium alone or together in pairs. Of the 238 girls with G. vaginalis, 63% had the sialidase A gene detected, though there was no difference by reported sexual activity (p = 0.197). Of the 191 girls with results for sialidase A gene and FISH, there was strong evidence for an increased presence of sialidase A gene among those with evidence of a biofilm (p < 0.001). There was a strong association between biofilm and non-optimal microbiota (aOR67.00; 95% CI 26.72–190.53). These results support several of the steps outlined in the conceptual model, although the role of sexual activity is less clear. We recommend longitudinal studies to better understand changes in vaginal microbiota and biofilm formation around the time of sexual debut.

Apoptosis of vaginal epithelial cells in clinical samples from women with diagnosed bacterial vaginosis

Bacterial vaginosis (BV) is one of the most common vaginal infections among women of childbearing age. Gardnerella vaginalis (G. vaginalis) is a keystone microorganism present in more than 95% of all BV cases. The first step of the infection process in BV is mediated by interaction of microorganisms with epithelial cells (ECs). However, the role of these cells in BV pathogenesis is largely unknown. The present study aimed to investigate the vaginal EC response during BV. Twenty healthy women and 34 women with BV were enrolled in this study. The number of ECs in the vaginal swab was counted and analyzed for intracellular signals and apoptosis by flow cytometry. Cell damage was evaluated by lactate dehydrogenase assay. Compared to that in healthy donors, the percentage of exfoliated vaginal ECs was increased in women with BV, and an absence of neutrophils was observed in both groups. Activation signals, such as p-IκBα and c-Fos were unmodulated in the vaginal ECs of women with BV. Moreover, EC damage and apoptosis were significantly increased in patients with BV. Apoptosis was related to caspase-3 activation and the presence of G. vaginalis. This study provides the first evidence of a direct involvement of G. vaginalis in the apoptotic process of vaginal ECs during BV. This effect was mediated by caspase-3 activation, and G. vaginalis appeared to be one of causes for inducing EC apoptosis in BV. Hence, our findings suggest a possible explanation for the increased exfoliation of ECs in the vagina during BV.

Host-vaginal microbiota interactions in the pathogenesis of bacterial vaginosis.

The cause of bacterial vaginosis, the most common cause of vaginal discharge in women, remains controversial. We recently published an updated conceptual model on bacterial vaginosis pathogenesis, focusing on the roles of Gardnerella vaginalis and Prevotella bivia as early colonizers and Atopobium vaginae and other bacterial vaginosis-associated bacteria (BVAB) as secondary colonizers in this infection. In this article, we extend the description of our model to include a discussion on the role of host-vaginal microbiota interactions in bacterial vaginosis pathogenesis. Although G. vaginalis and P. bivia are highly abundant in women with bacterial vaginosis, neither induce a robust inflammatory response from vaginal epithelial cells. These early colonizers may be evading the immune system while establishing the bacterial vaginosis biofilm. Secondary colonizers, including A. vaginae, Sneathia spp., and potentially other BVAB are more potent stimulators of the host-immune response to bacterial vaginosis and likely contribute to its signs and symptoms as well as its adverse outcomes. Elucidating the cause of bacterial vaginosis has important implications for diagnosis and treatment. Our current bacterial vaginosis pathogenesis model provides a framework for key elements that should be considered when designing and testing novel bacterial vaginosis diagnostics and therapeutics.

Characterization of Gardnerella vaginalis membrane vesicles reveals a role in inducing cytotoxicity in vaginal epithelial cells

Bacterial vaginosis (BV) is a common polymicrobial infection affecting women in the reproductive age and is associated with adverse obstetric and gynaecological outcomes. Gardnerella vaginalis is the most virulent anaerobic bacterial species predominantly associated with BV. However, a clear understanding of the mechanisms by which it contributes to the pathogenesis and persistence of BV is lacking. In this report, we demonstrate for the first time, the isolation of membrane vesicles (MVs) from G. vaginalis ATCC 14019. These MVs are approximately 120–260 nm in diameter. Proteomic characterization of the MVs by LC-MS/MS led to the identification of 417 proteins, including proteins involved in cellular metabolism as well as molecular chaperones and certain virulence factors. Immunoblot analysis of the MVs confirmed the presence of vaginolysin, the most well-characterized virulence factor of G. vaginalis. The exposure of the vaginal epithelial cells, VK2/E6E7 to the G. vaginalis MVs resulted in the internalization of the MVs. The MVs induced cytotoxicity and an increase in the levels of the pro-inflammatory cytokine, IL-8 in VK2 cells as well lysis of erythrocytes. The results of the study indicate that G. vaginalis MVs may be involved in the delivery of cytotoxic proteins and other virulence factors to the host cells and could thereby contribute towards enhancing the cellular damage associated with pathogenesis of BV.

An Updated Conceptual Model on the Pathogenesis of Bacterial Vaginosis.

Bacterial vaginosis (BV) is the most common cause of vaginal discharge. It is associated with an increased risk of preterm delivery, pelvic inflammatory disease, and an increased risk of acquisition of sexually transmitted infections including human immunodeficiency virus (HIV). The epidemiology of BV supports sexual transmission. However, its etiology remains unknown. At the center of the debate is whether BV is caused by a primary pathogen or a polymicrobial consortium of microorganisms that are sexually transmitted. We previously published a conceptual model hypothesizing that BV is initiated by sexual transmission of Gardnerella vaginalis. Critics of this model have iterated that G. vaginalis is found in virginal women and in sexually active women with a normal vaginal microbiota. In addition, colonization does not always lead to BV. However, recent advances in BV pathogenesis research have determined the existence of 13 different species within the genus Gardnerella. It may be that healthy women are colonized by nonpathogenic Gardnerella species, whereas virulent strains are involved in BV development. Based on our results from a recent prospective study, in addition to an extensive literature review, we present an updated conceptual model for the pathogenesis of BV that centers on the roles of virulent strains of G. vaginalis, as well as Prevotella bivia and Atopobium vaginae.

Gardnerella vaginalis: genotypic and phenotypic diversity, virulence factors and role in the pathogenesis of bacterial vaginosis

This review summarizes literature data on the structure, biological characteristics, and virulence factors of Gardnerella vaginalis. Genotypic and phenotypic diversity of the bacterium, as well as its role in bacterial vaginosis are highlighted.

Gardnerella vaginalis and Prevotella bivia Trigger Distinct and Overlapping Phenotypes in a Mouse Model of Bacterial Vaginosis.

Bacterial vaginosis (BV) is a common imbalance of the vaginal microbiota characterized by overgrowth of diverse Actinobacteria, Firmicutes, and Gram-negative anaerobes. Women with BV are at increased risk of secondary reproductive tract infections and adverse pregnancy outcomes. However, which specific bacteria cause clinical features of BV is unclear. We previously demonstrated that Gardnerella vaginalis could elicit many BV features in mice. In this study, we established a BV model in which we coinfected mice with G. vaginalis and another species commonly found in women with BV: Prevotella bivia. This coinfection model recapitulates several aspects of human BV, including vaginal sialidase activity (a diagnostic BV feature independently associated with adverse outcomes), epithelial exfoliation, and ascending infection. It is notable that G. vaginalis facilitated uterine infection by P. bivia. Taken together, our model provides a framework for advancing our understanding of the role of individual or combinations of BV-associated bacteria in BV pathogenesis.

Loop-mediated isothermal amplification for the rapid detection of Gardnerella vaginalis.

The aim of this study was to develop a method for the rapid detection of Gardnerella vaginalis, which is proposed to play a key role in the pathogenesis of bacterial vaginosis. Specific loop-mediated isothermal amplification (LAMP) primers were designed and used to detect target DNA within 45 min under isothermal conditions. Comparative screening indicated that the LAMP assay is superior to PCR in terms of rapidity, and is equivalent in sensitivity and specificity. This LAMP assay can be used for rapid screening and detection of G. vaginalis in vaginal samples; the limit of detection is 10 fg DNA.

Present-day trends in treatment of bacterial vaginosis

The most frequent infectious disease of the female reproductive system is bacterial vaginosis (BV). The increased interest in this nosology is explained by the clinical manifestation severity of the disease, rather than numerous data indicating the inextricable connection between BV and inflammatory diseases of female genitourinary system and the complications of pregnancy and delivery. The bacterial biofilm formation, which is found in 90% of cases, have been shown to provide bacteria with protection against antimicrobial agents, representing the specificity of the BV pathogenesis, which militates against the effectiveness of the treatment. The official guidelines recommend to use metronidazole and clindamycin as the first-line therapy for BV in Russia and abroad. However, the present-day concept of BV therapy provides for a comprehensive two-stage treatment with a wide range of combination drugs to eradicate BV-associated microorganisms. Due to the lack of a systemic effect, the preference should be given to combination drugs designed for local therapy. Tergynan is one of the most popular drugs used for topical BV therapy, which demonstrated clinical efficacy and ease of use. Analogue of Tergynan, ornidazole + neomycin + prednisolone + econazole is a topical drug with antibacterial, antifungal and anti-inflammatory components, but has more modern antibacterial (ornidazole) and antifungal (econazole) components. The Russian studies showed convincing efficacy, safety and ease of use of a drug containing ornidazole + neomycin + prednisolone + econazole in BV therapy, which makes it possible to recommend it for practical use.

Women view key sexual behaviours as the trigger for the onset and recurrence of bacterial vaginosis.

BackgroundBacterial vaginosis (BV) affects a third of women of reproductive age in the US and there is increasing evidence to suggest it may be sexually transmitted. This study aimed to extend and validate the findings of our earlier smaller qualitative study by exploring in detail women’s views and experiences of the triggering factors associated with BV onset and recurrence.MethodsWomen aged 20–49, who had experienced one or more symptomatic episode of BV within 6 months, were opportunistically recruited to complete a 38-item questionnaire on their experience of BV.Results103 women completed the questionnaire. Women were significantly more likely to report sexual than lifestyle factors triggered BV onset and recurrence (p<0.001). The top 3 factors women attributed to both BV onset and recurrence were identical–and all sexual. They included, in order: 1) unprotected sex; 2) sex with a new male partner; and 3) sex in general. The main lifestyle factors nominated included stress, diet, menstruation and the use of feminine hygiene products. While many women felt their BV had been transmitted through sexual contact (54%) and developed as a result of sexual activity (59%), few considered BV a sexually transmitted infection (STI) (10%). Despite this 57% felt partners should also be treated for BV.ConclusionThese data concur with our earlier qualitative findings that women believe BV is triggered by sexual activity. While many women felt BV was sexually transmitted and supported partner treatment, they did not consider BV an STI. This contradiction is likely due to information conveyed to women based on current guidelines. In the absence of highly effective BV treatments, this study highlights the need for guidelines to indicate there is scientific uncertainty around the pathogenesis of BV and to contain clear health messages regarding the evidence for practices shown to be associated with a reduced risk of BV (i.e. consistent condom use.

Comparative transcriptomic analysis of Gardnerella vaginalis biofilms vs. planktonic cultures using RNA-seq

Bacterial vaginosis is the most common gynecological disorder affecting women of reproductive age. Bacterial vaginosis is frequently associated with the development of a Gardnerella vaginalis biofilm. Recent data indicates that G. vaginalis biofilms are more tolerant to antibiotics and are able to incorporate other bacterial vaginosis -associated species, yielding a multi-species biofilm. However, despite its apparent role in bacterial vaginosis, little is known regarding the molecular determinants involved in biofilm formation by G. vaginalis. To gain insight into the role of G. vaginalis in the pathogenesis of bacterial vaginosis, we carried out comparative transcriptomic analysis between planktonic and biofilm phenotypes, using RNA-sequencing. Significant differences were found in the expression levels of 815 genes. A detailed analysis of the results obtained was performed based on direct and functional gene interactions. Similar to other bacterial species, expression of genes involved in antimicrobial resistance were elevated in biofilm cells. In addition, our data indicate that G. vaginalis biofilms assume a characteristic response to stress and starvation conditions. The abundance of transcripts encoding proteins involved in glucose and carbon metabolism was reduced in biofilms. Surprisingly, transcript levels of vaginolysin were reduced in biofilms relative to planktonic cultures. Overall, our data revealed that gene-regulated processes in G. vaginalis biofilms resulted in a protected form of bacterial growth, characterized by low metabolic activity. This phenotype may contribute towards the chronic and recurrent nature of bacterial vaginosis. This suggests that G. vaginalis is capable of drastically adjusting its phenotype through an extensive change of gene expression.

Antimicrobial susceptibility and vaginolysin in Gardnerella vaginalis from healthy and bacterial vaginosis diagnosed women.

Bacterial vaginosis (BV) is a syndrome related to Gardnerella vaginalis and is characterized by an imbalance in the vaginal microbiota. This work focused on the evaluation of antimicrobial susceptibility patterns and the occurrence of the vaginolysin (vly) gene in G. vaginalis isolated from BV and non-BV patients. The vaginal secretions were collected randomly and processed for G. vaginalis isolation. The isolates were presumptively identified by β-hemolysis and oxidase and catalase tests. Polymerase chain reaction (PCR) was performed to confirm bacterial identity and to detect the vly gene. Antimicrobial susceptibility patterns were determined. Of 89 patients, G. vaginalis was isolated from 42 (37 BV and 5 non-BV), and 204 isolates were selected (179 from BV and 25 non-BV). The vly gene was detected in all G. vaginalis isolated from non-BV women and in 98.3% of the bacteria from BV patients. High resistance was observed for ampicillin (54.4%), metronidazole (59.8%), tinidazole (60.3%) and secnidazole (71.6%). Further studies are needed to better address the role of G. vaginalis and the vly gene in BV pathogenesis.

Pathogenesis of Bacterial Vaginosis: Discussion of Current Hypotheses.

In April 2015, the Division of Microbiology and Infectious Diseases of the National Institute of Allergy and Infectious Diseases hosted an experts technical consultation on bacterial vaginosis (BV), where data regarding controversies over the pathogenesis of BV were discussed. The discussion on the epidemiology and pathogenesis of BV is presented here, and several hypotheses on its pathogenesis are critiqued. Rigorous hypothesis-driven studies are needed to ultimately determine the cause of BV. This information is vital for the prevention and control of this important infection and its adverse public health consequences.

The Vaginal Microbiome: Current Understanding and Future Directions.

This article summarizes the highlights of the expert technical consultation on bacterial vaginosis (BV), sponsored by the National Institute of Allergy and Infectious Disease and held in Washington, DC, on 8-9 April 2015. Many issues touched on in this article are discussed in much greater detail in the 6 preceding articles in this supplement to The Journal of Infectious Diseases There was a consensus among the meeting attendees concerning the most important research issues in the field: the pathogenesis of the syndrome, way to optimize treatment, and the relative roles of sexual transmission and endogenous infection in BV epidemiology. This article concludes with a listing of BV and genitourinary tract research priorities that were discussed and agreed on by attendees. The most important of these included better characterization of vaginal microbiome community state subtypes, application of advanced "-omic" technologies to improve understanding of BV pathogenesis, further investigation of the relationships between the male and female genitourinary tract microbiomes, and the development of new drugs for BV treatment.

Can one size fit all? Approach to bacterial vaginosis in sub-Saharan Africa.

Bacterial vaginosis (BV) is the most common vaginal disorder affecting women of reproductive age and is associated with increased risk of sexually transmitted infections such as human immunodeficiency syndrome (HIV-1). Sub-Saharan Africa has the highest BV and HIV-1 burden and yet very few studies have focused on understanding the aetiology of BV and its association with HIV in this region. It has been suggested that we need to accurately diagnose and treat BV to lower the risk of HIV infection globally. However, effective diagnosis requires knowledge of what constitutes a “healthy” cervicovaginal microbiome and current studies indicate that Lactobacillus crispatus might not be the only commensal protective against BV: healthy women from different countries and ethnicities harbour alternative commensals. Microbiotas associated with BV have also shown global variation, further complicating effective diagnosis via culture-based assays as some species are difficult to grow. Antibiotics and probiotics have been suggested to be key in controlling BV infection, but the efficacy of this treatment might rely on reconstituting endogenous commensals while targeting a specific species of BV-associated bacteria (BVAB). Alternatively, therapy could inhibit essential BV bacterial growth factors e.g. sialidases or provide anti-microbial compounds e.g. lactic acid associated with a healthy cervicovaginal microbiome. But without global investigation into the mechanism of BV pathogenesis and its association with HIV, selection of such compounds could be limited to Caucasian women from certain regions. To confirm this suggestion and guide future therapy we require standardised diagnostic assays and research methodologies. This review will focus on research papers that describe the global variation of BV aetiology and how this influences the identification of determinants of BV pathogenesis and potential probiotic and antimicrobial therapy.