The Vaginal Microbiome in U.S. Black Women: A Systematic Review

VagiBIOM Lactobacillus suppository improves vaginal health index in perimenopausal women with bacterial vaginosis: a randomized control trial

Bacterial vaginosis (BV) can cause vaginal dysbiosis that may influence general vaginal health and pregnancy complications. Balancing vaginal microbiome using Lactobacillus spp. may be a new way to prevent and treat mild BV. We conducted a randomized, double-blind, placebo-controlled pilot study aimed at evaluating the effect of the product VagiBIOM, a multi-Lactobacillus vaginal suppository, on peri- and premenopausal women with BV in restoring vaginal pH and overall vaginal health by resetting the vaginal microbiome composition. Sixty-six peri- and premenopausal women with BV symptoms were randomized with a 2:1 ratio to be treated with VagiBIOM or placebo suppositories. Vaginal pH, VAS itching score, total Nugent score, and vaginal health index (VHI) were measured. Vaginal microbiome changes before and after the treatment were analyzed by 16S rRNA sequencing and bioinformatics analysis. After 4 weeks of intervention with VagiBIOM or a placebo, the mean score for vaginal pH, VAS itching, and total Nugent score was significantly decreased from the baseline. Compared to the baseline scores, the VHI scores improved significantly following 28-day intervention (p < 0.001). Our results revealed two Lactobacillus species, L. hamsteri, and L. helveticus, as indicator species occurring differentially in the VagiBIOM-treated group. Furthermore, the regression and species network analyses revealed significant bacterial associations after VagiBIOM treatment. Lactobacillus hamsteri was positively associated with the Nugent score and negatively associated with vaginal pH. L. iners and L. salivarius were positively and inversely associated with VHI. As is typical, Bacteroides fragilis was positively associated with vaginal pH and negatively associated with the Nugent score. Interestingly, the Lactobacillus spp. diversity improved after VagiBIOM treatment. The VagiBIOM suppository treatment for peri- and premenopausal women with BV significantly relieved vaginal itching by decreasing vaginal pH and Nugent scores and improving the overall VHI after 4 weeks' intervention. This effect was primarily the result of VagiBIOM improving vaginal Lactobacillus diversity.Trial Registration ClinicalTrials.gov registration: NCT05060029, first registration 09/28/2021: Title: A Pilot Study to Evaluate the Efficacy and Safety of Lactobacillus Species Suppositories on Vaginal Health and pH.

Maternal vaginal microbiome composition does not affect development of the infant gut microbiome in early life

Birth mode has been implicated as a major factor influencing neonatal gut microbiome development, and it has been assumed that lack of exposure to the maternal vaginal microbiome is responsible for gut dysbiosis among caesarean-delivered infants. Consequently, practices to correct dysbiotic gut microbiomes, such as vaginal seeding, have arisen while the effect of the maternal vaginal microbiome on that of the infant gut remains unknown. We conducted a longitudinal, prospective cohort study of 621 Canadian pregnant women and their newborn infants and collected pre-delivery maternal vaginal swabs and infant stool samples at 10-days and 3-months of life. Using cpn60-based amplicon sequencing, we defined vaginal and stool microbiome profiles and evaluated the effect of maternal vaginal microbiome composition and various clinical variables on the development of the infant stool microbiome. Infant stool microbiomes showed significant differences in composition by delivery mode at 10-days postpartum; however, this effect could not be explained by maternal vaginal microbiome composition and was vastly reduced by 3 months. Vaginal microbiome clusters were distributed across infant stool clusters in proportion to their frequency in the overall maternal population, indicating independence of the two communities. Intrapartum antibiotic administration was identified as a confounder of infant stool microbiome differences and was associated with lower abundances of Escherichia coli, Bacteroides vulgatus, Bifidobacterium longum and Parabacteroides distasonis. Our findings demonstrate that maternal vaginal microbiome composition at delivery does not affect infant stool microbiome composition and development, suggesting that practices to amend infant stool microbiome composition focus factors other than maternal vaginal microbes.

Novel Vaccine Strategies and Factors to Consider in Addressing Health Disparities of HPV Infection and Cervical Cancer Development among Native American Women

Cervical cancer is the 4th most common type of cancer in women world-wide. Many factors play a role in cervical cancer development/progression that include genetics, social behaviors, social determinants of health, and even the microbiome. The prevalence of HPV infections and cervical cancer is high and often understudied among Native American communities. While effective HPV vaccines exist, less than 60% of 13- to 17-year-olds in the general population are up to date on their HPV vaccination as of 2020. Vaccination rates are higher among Native American adolescents, approximately 85% for females and 60% for males in the same age group. Unfortunately, the burden of cervical cancer remains high in many Native American populations. In this paper, we will discuss HPV infection, vaccination and the cervicovaginal microbiome with a Native American perspective. We will also provide insight into new strategies for developing novel methods and therapeutics to prevent HPV infections and limit HPV persistence and progression to cervical cancer in all populations.

Microbiota succession throughout life from the cradle to the grave

Associations between age and the human microbiota are robust and reproducible. The microbial composition at several body sites can predict human chronological age relatively accurately. Although it is largely unknown why specific microorganisms are more abundant at certain ages, human microbiota research has elucidated a series of microbial community transformations that occur between birth and death. In this Review, we explore microbial succession in the healthy human microbiota from the cradle to the grave. We discuss the stages from primary succession at birth, to disruptions by disease or antibiotic use, to microbial expansion at death. We address how these successions differ by body site and by domain (bacteria, fungi or viruses). We also review experimental tools that microbiota researchers use to conduct this work. Finally, we discuss future directions for studying the microbiota's relationship with age, including designing consistent, well-powered, longitudinal studies, performing robust statistical analyses and improving characterization of non-bacterial microorganisms.

Association of key species of vaginal bacteria of recurrent bacterial vaginosis patients before and after oral metronidazole therapy with short- and long-term clinical outcomes

Bacterial vaginosis (BV) is associated with a state of vaginal dysbiosis typically involving depletion of otherwise dominant populations of Lactobacillus. The causes of this microbial succession are not known; there may be multiple causes. Standard treatment includes oral metronidazole, which typically restores Lactobacillus species to dominance. However, recurrence rates are high; recurrent BV patients recur 3–4 times annually and are often refractory to treatment. Our previous qPCR-based study of recurrent BV patients pointed to putatively more virulent species of Gardnerella that were associated with refractory responses to oral metronidazole, and less robust recovery of Lactobacillus species associated with recurrence after an initial period of remission. However, these associations did not account for outcomes in all patients, suggesting that other bacterial species were involved. In this follow-up study, we sequenced the V4 domain of 16S rRNA sequences of 41of these same patients pre- and posttreatment. Overall compositions among pretreatment clinical outcome groups were not different, although alpha diversity significantly decreased: refractory > recurrent > remission. Combinations of key species were associated with and prognostic for outcome. Higher pretreatment abundance of Megasphaera lornae together with lower abundance of Gardnerella Gsp07 and Finegoldia magna predicted long term remission after oral metronidazole. Furthermore, a subset of refractory patients that did not have high levels of Gardnerella Gsp07, instead had elevated levels of alternative species including Atopobium vaginae, Mageeibacillus indolicus (BVAB3), and Prevotella timonensis. Patients who recurred after transient remission had elevated abundance of species including Atopobium vaginae, Gardnerella, and Aerococcus christensenii, compared to long-term remission patients. Core bacterial species among refractory patients did not change in abundance after metronidazole, suggesting resistance or tolerance, in contrast to the loss in abundance of the same species among recurrent or remission patients. These findings have potential prognostic and therapeutic implications.

Evaluation and Management of Vaginitis

Vaginitis is a common concern for women across the lifespan. Vaginal symptoms may impact quality of life, and clinicians are challenged in the evaluation and management of bacterial vaginosis, Candida vaginitis, trichomoniasis, desquamative inflammatory vaginitis, and genitourinary syndrome of menopause.

Differences in gut microbiome by insulin sensitivity status in Black and White women of the National Growth and Health Study (NGHS): A pilot study

The prevalence of overweight and obesity is greatest amongst Black women in the U.S., contributing to disproportionately higher type 2 diabetes prevalence compared to White women. Insulin resistance, independent of body mass index, tends to be greater in Black compared to White women, yet the mechanisms to explain these differences are not completely understood. The gut microbiome is implicated in the pathophysiology of obesity, insulin resistance and cardiometabolic disease. Only two studies have examined race differences in Black and White women, however none characterizing the gut microbiome based on insulin sensitivity by race and sex. Our objective was to determine if gut microbiome profiles differ between Black and White women and if so, determine if these race differences persisted when accounting for insulin sensitivity status. In a pilot cross-sectional analysis, we measured the relative abundance of bacteria in fecal samples collected from a subset of 168 Black (n = 94) and White (n = 74) women of the National Growth and Health Study (NGHS). We conducted analyses by self-identified race and by race plus insulin sensitivity status (e.g. insulin sensitive versus insulin resistant as determined by HOMA-IR). A greater proportion of Black women were classified as IR (50%) compared to White women (30%). Alpha diversity did not differ by race nor by race and insulin sensitivity status. Beta diversity at the family level was significantly different by race (p = 0.033) and by the combination of race plus insulin sensitivity (p = 0.038). Black women, regardless of insulin sensitivity, had a greater relative abundance of the phylum Actinobacteria (p = 0.003), compared to White women. There was an interaction between race and insulin sensitivity for Verrucomicrobia (p = 0.008), where among those with insulin resistance, Black women had four fold higher abundance than White women. At the family level, we observed significant interactions between race and insulin sensitivity for Lachnospiraceae (p = 0.007) and Clostridiales Family XIII (p = 0.01). Our findings suggest that the gut microbiome, particularly lower beta diversity and greater Actinobacteria, one of the most abundant species, may play an important role in driving cardiometabolic health disparities of Black women, indicating an influence of social and environmental factors on the gut microbiome.

The vaginal microbiome in women of reproductive age with healthy weight versus overweight/obesity

OBJECTIVE

The aim of this study was to evaluate the differences between the vaginal microbiome of reproductive-aged women with overweight and obesity (Ow/Ob) compared with healthy weight (HW).

METHODS

In this case-control study, a cohort of 367 nonpregnant women (18 to 40 years) with Ow/Ob (BMI ≥25 kg/m² ) was case-matched with 367 women with HW (BMI 18.0 to 24.9 kg/m² ). The study was a secondary analysis of 16S rRNA vaginal microbiome surveys through the Vaginal Human Microbiome Study (VaHMP). Groups were matched on age, race/ethnicity, income, and nulliparity status.

RESULTS

Mean age and BMI of Ow/Ob and HW groups were 26.8 versus 26.7 years and 37.0 versus 22.1 kg/m² , respectively. The overall vaginal microbiome composition differed between groups (PERMANOVA, p = 0.035). Women with Ow/Ob had higher alpha diversity compared with women with HW (Wilcoxon test, Shannon index p = 0.025; inverse Simpson index p = 0.026). Lactobacillus dominance (≥30% proportional abundance) was observed in a greater proportion of women with HW (48.7%) compared with Ow/Ob (40.1%; p = 0.026).

CONCLUSIONS

The vaginal microbiome differs in reproductive-aged women with Ow/Ob compared with women with HW, with increased alpha diversity and decreased predominance of Lactobacillus. Observed differences in the vaginal microbiome may partially explain differences in preterm birth and bacterial vaginosis risk between these populations.

Contribution of Lactobacillus iners to Vaginal Health and Diseases: A Systematic Review

Lactobacillus iners, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As L. iners does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically on blood agar, it has been initially overlooked by traditional culture methods. It was not until the wide application of molecular biology techniques that the function of L. iners in the vaginal microbiome was carefully explored. L. iners has the smallest genome among known Lactobacilli and it has many probiotic characteristics, but is partly different from other major vaginal Lactobacillus species, such as L. crispatus, in contributing to the maintenance of a healthy vaginal microbiome. It is not only commonly present in the healthy vagina but quite often recovered in high numbers in bacterial vaginosis (BV). Increasing evidence suggests that L. iners is a transitional species that colonizes after the vaginal environment is disturbed and offers overall less protection against vaginal dysbiosis and, subsequently, leads to BV, sexually transmitted infections, and adverse pregnancy outcomes. Accordingly, under certain conditions, L. iners is a genuine vaginal symbiont, but it also seems to be an opportunistic pathogen. Further studies are necessary to identify the exact role of this intriguing species in vaginal health and diseases.

Changes in the Vaginal Microbiome and Associated Toxicities Following Radiation Therapy for Gynecologic Cancers

Postmenopausal women often suffer from vaginal symptoms associated with atrophic vaginitis. Additionally, gynecologic cancer survivors may live for decades with additional, clinically significant, persistent vaginal toxicities caused by cancer therapies, including pain, dyspareunia, and sexual dysfunction. The vaginal microbiome (VM) has been previously linked with vaginal symptoms related to menopause (i.e. dryness). Our previous work showed that gynecologic cancer patients exhibit distinct VM profiles from healthy women, with low abundance of lactobacilli and prevalence of multiple opportunistic pathogenic bacteria. Here we explore the association between the dynamics and structure of the vaginal microbiome with the manifestation and persistence of vaginal symptoms, during one year after completion of cancer therapies, while controlling for clinical and sociodemographic factors. We compared cross-sectionally the vaginal microbiome in 134 women, 64 gynecologic patients treated with radiotherapy and 68 healthy controls, and we longitudinally followed a subset of 52 women quarterly (4 times in a year: pre-radiation therapy, 2, 6 and 12 months post-therapy). Differences among the VM profiles of cancer and healthy women were more pronounced with the progression of time. Cancer patients had higher diversity VMs and a variety of vaginal community types (CTs) that are not dominated by Lactobacilli, with extensive VM variation between individuals. Additionally, cancer patients exhibit highly unstable VMs (based on Bray-Curtis distances) compared to healthy controls. Vaginal symptoms prevalent in cancer patients included vaginal pain (40%), hemorrhage (35%), vaginismus (28%) and inflammation (20%), while symptoms such as dryness (45%), lack of lubrication (33%) and dyspareunia (32%) were equally or more prominent in healthy women at baseline. However, 24% of cancer patients experienced persistent symptoms at all time points, as opposed to 12% of healthy women. Symptom persistence was strongly inversely correlated with VM stability; for example, patients with persistent dryness or abnormally high pH have the most unstable microbiomes. Associations were identified between vaginal symptoms and individual bacterial taxa, including: Prevotella with vaginal dryness, Delftia with pain following vaginal intercourse, and Gemillaceaea with low levels of lubrication during intercourse. Taken together our results indicate that gynecologic cancer therapy is associated with reduced vaginal microbiome stability and vaginal symptom persistence.

Vaginal microbiome Lactobacillus crispatus is heritable among European American women

The diversity and dominant bacterial taxa in the vagina are reported to be influenced by multiple intrinsic and extrinsic factors, including but not limited to pregnancy, contraceptive use, pathogenic states, socioeconomic status, and ancestry. However, the extent to which host genetic factors influence variation in the vaginal microbiota is unclear. We used a biometrical genetic approach to determine whether host genetic factors contribute to inter-individual differences in taxa from a sample of 332 twins who self-identified as being of African (44 pairs) or European ancestry (122 pairs). Lactobacillus crispatus, a major determinant of vaginal health, was identified as heritable among European American women (narrow-sense heritability = 34.7%, P-value = 0.018). Heritability of L. crispatus is consistent with the reduced prevalence of adverse reproductive disorders, including bacterial vaginosis and preterm birth, among women of European ancestry.

Wright et al. apply biometric genetic approach to identify the extent to which host genetic factors influence species-level variation in the vaginal microbiota. Their study suggests that Lactobacillus crispatus, a major determinant of vaginal health, is heritable among European American women, consistent with the reduced prevalence of adverse reproductive disorders in them.

Adapting to Challenging Circumstances: Pessary Care in a Racially Diverse Urban Population Within a U.S. Epicenter of the COVID-19 Pandemic

Objectives

The aim of the study was to describe time intervals between pessary maintenance visits in racially diverse women receiving care in a U.S. epicenter of the COVID-19 pandemic. We secondarily aimed to determine whether time interval between pessary changes is associated with adverse outcomes and to identify factors associated with adverse pessary outcomes.

Methods

We performed a retrospective study of women undergoing pessary care after the COVID-19 pandemic began. Time between the most recent visit before the pandemic and first visit after the pandemic began was recorded. Pessary care data were collected from the latter visit, including vaginal bleeding, vaginal discharge, and erosion. Patient-reported symptoms and demographics were also recorded. The relationship between time interval between pessary visits and adverse outcomes as well as between adverse outcomes and demographic data was assessed.

Results

We identified 104 women undergoing pessary care, of which 35.6% were Hispanic and 32.7% were Black and 26.2% ± 10.5% lived in poverty. The median time to in-person visit was 4.5 months (interquartile range, 3.7–5.3 months). Seven women (8.7%) had vaginal bleeding, 15 (14.6%) had vaginal discharge, and 7 (6.8%) had erosions. There was no significant association between time interval between pessary visits and adverse outcomes or between adverse outcomes and patient characteristics (all P > 0.05).

Conclusions

Longer duration of time between pessary maintenance visits is not associated with increased adverse outcomes in this group of racially diverse women. Extended intervals between pessary visits can be considered to minimize risk and maintain patient safety during challenging circumstances, such as the COVID-19 pandemic.

Recent sexual violence exposure is associated with immune biomarkers of HIV susceptibility in women

PROBLEM

HIV/AIDS and sexual violence act synergistically and compromise women's health. Yet, immuno-biological mechanisms linking sexual violence and increased HIV susceptibility are poorly understood.

METHODS

We conducted a cross-sectional pilot study of HIV-uninfected women, comparing 13 women exposed to forced vaginal penetration within the past 12 weeks (Exposed) with 25 Non-Exposed women. ELISA assays were conducted for 49 biomarkers associated with HIV pathogenesis in plasma and cervicovaginal lavage (CVL). Differences between Exposed and Non-Exposed were analyzed by linear and logistic regression, using propensity score weighting to control for age, race, socioeconomic status, menstrual cycle, and contraceptive use.

RESULTS

In CVL, Exposed women had significantly reduced chemokines MIP-3α (p < .01), MCP-1 (p < .01), and anti-HIV/wound-healing thrombospondin-1 (p = .03). They also had significantly increased inflammatory cytokine IL-1α (p < 0.01) and were more likely to have detectable wound-healing PDGF (p = .02). In plasma, Exposed women had reduced chemokines MIP-3α (p < .01) and IL-8 (p < .01), anti-inflammatory cytokine TGF-β (p = .02), anti-HIV/antimicrobial HBD-2 (p = .02), and wound-healing MMP-1 (p = 0.02). They also had increased thrombospondin-1 (p < .01) and Cathepsin B (p = .01). After applying the stringent method of false discovery rate adjustment, differences for IL-1α (p = .05) and MCP-1 (p = .03) in CVL and MIP-3α (p = .03) in plasma remained significant.

CONCLUSIONS

We report systemic and mucosal immune dysregulation in women exposed to sexual violence. As these biomarkers have been associated with HIV pathogenesis, dysregulation may increase HIV susceptibility.

Vaginal microbial profiling in a preterm birth high-risk cohort using shallow shotgun metagenomics

Preterm birth (PTB) is a significant health problem globally, with an estimate of 15 million cases annually. Approximately 10% of neonates born early will die prematurely, while a subset will develop severe life-long morbidities. Unfortunately, preterm birth’s syndromic nature has evaded prevention strategies, and it continues to impose a high burden on healthcare systems and families. The role of vaginal bacteria in triggering biomolecular causes of PTB has been recognised for years. However, translating this knowledge to practical diagnostic and therapeutic strategies has remained elusive. New techniques in high-throughput sequencing have improved our understanding of the nature and role of the vaginal microbiome during pregnancy. Several multi-ethnic and multi-geographical studies into the vaginal microbiome have identified five distinct bacterial profiles termed community state types (CSTs), one of which is positively associated with dysbiosis and increased risk of PTB. In a small pilot study of first-trimester vaginal microbial DNA obtained from pregnant women at high-risk of PTB, we compared the CST profiles generated using standard 16S amplicon sequencing with shallow shotgun metagenomics (SSM). Both methods identified the presence of the five CSTs as has been reported previously, although the metagenomic data showed greater taxonomic resolution and more accurate CST assignation. These findings suggest that SSM is a cost-effective and potentially superior alternative to 16S sequencing for vaginal microbiome analysis.

Adaptive response to iterative passages of five Lactobacillus species in simulated vaginal fluid

Background

Microbiome and metagenomic studies have given rise to a new understanding of microbial colonization of various human tissues and their ability to impact our health. One human microbiome growing in notoriety, the vaginal microbiome, stands out given its importance for women’s health, and is peculiar in terms of its relative bacterial composition, including its simplicity and typical domination by a small number of Lactobacillus species. The loss of Lactobacillus dominance is associated with disorders such as bacterial vaginosis, and efforts are now underway to understand the ability of Lactobacillus species to colonize the vaginal tract and adapt to this dynamic and acidic environment. Here, we investigate how various Lactobacillus species often isolated from the vaginal and intestinal cavities genomically and transcriptionally respond to iterative growth in simulated vaginal fluid.

Results

We determined the genomes and transcriptomes of L. acidophilus, L. crispatus, L. fermentum, L. gasseri, and L. jensenii and compared profiles after 50, 100, 500, and 1000 generations of iterative passages in synthetic vaginal fluid. In general, we identified relatively few genetic changes consisting of single nucleotide polymorphisms, with higher counts occurring more frequently in non-vaginal isolated species. Transcriptional profiles were more impacted over time and tended to be more extensive for species that typically do not dominate the vaginal tract, reflecting a more extensive need to adapt to a less familiar environment.

Conclusions

This study provides insights into how vaginal and non-vaginal Lactobacillus species respond and adapt to a simulated vaginal environment. Overall, trends indicate high genomic stability for all species involved, with more variability in the transcriptome especially for non-dominant species of the vaginal tract.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-020-02027-8.