Ecological dynamics of the vaginal microbiome in relation to health and disease

Characteristics of the vaginal microbiome in women with and without clinically confirmed vulvodynia

BACKGROUND

Vulvodynia (idiopathic vulvar pain) affects up to 8% of women by age 40 years, has a poorly understood etiology, and has variable treatment efficacy. Several risk factors are associated with vulvodynia from a history of yeast infections to depression and allergies. Recent work suggests an altered immune inflammatory mechanism plays a role in vulvodynia pathophysiology. Because the vaginal microbiome plays an important role in local immune-inflammatory responses, we evaluated the vaginal microbiome among women with vulvodynia compared with controls as 1 component of the immune system.

OBJECTIVE

The objective of the study was to characterize the vaginal microbiome in women with clinically confirmed vulvodynia and age-matched controls and assess its overall association with vulvodynia and how it may serve to modify other factors that are associated with vulvodynia as well.

STUDY DESIGN

We conducted a case-control study of 234 Minneapolis/Saint Paul-area women with clinically confirmed vulvodynia and 234 age-matched controls clinically confirmed with no history of vulvar pain. All participants provided vulvovaginal swab samples for culture-based and non-culture (sequencing)-based microbiological assessments, background and medical history questionnaires on demographic characteristics, sexual and reproductive history, and history of psychosocial factors. Vaginal microbiome diversity was assessed using the Shannon alpha diversity Index. Data were analyzed using logistic regression.

RESULTS

Culture and molecular-based analyses of the vaginal microbiome showed few differences between cases and controls. However, among women with alpha diversity below the median (low), there was a strong association between increasing numbers of yeast infections and vulvodynia onset, relative to comparable time periods among controls (age-adjusted odds ratio, 8.1, 95% confidence interval, 2.9-22.7 in those with 5 or more yeast infections). Also among women with low-diversity microbiomes, we observed a strong association between moderate to severe childhood abuse, antecedent anxiety, depression, and high levels of rumination and vulvodynia with odds ratios from 1.83 to 2.81. These associations were not observed in women with high-diversity microbiomes.

CONCLUSION

Although there were no overall differences in microbiome profiles between cases and controls, vaginal microbiome diversity influenced associations between environmental and psychosocial risk factors and vulvodynia. However, it is unclear whether vaginal diversity modifies the association between the risk factors and vulvodynia or is altered as a consequence of the associations.

The effect of pathophysiological changes in the vaginal milieu on the signs and symptoms of genitourinary syndrome of menopause (GSM)

IMPORTANCE AND OBJECTIVE

The aim of this study was to provide an overview of the most recent literature on genitourinary syndrome of menopause (GSM), to explore the key elements of GSM diagnosis, and the potential impact of pathophysiological changes in the vaginal milieu on vulvovaginal symptoms.

METHODS

The MEDLINE database was searched, and only articles written in English were considered. Additional references were identified by hand searching the bibliographies of the included articles.

DISCUSSIONS AND CONCLUSION

The vaginal milieu plays important roles in producing bothersome symptoms in the host. In women with GSM, low hormone states can result in pathophysiological changes in the vaginal milieu, including the vaginal microbiome and the mucosal immunity. Hormone-associated disruption of the balance of the indigenous microbiota and the dysregulation of these immune responses are the pathophysiological basis of GSM symptoms. However, whether the microbiome and mucosal immunity are markers of vulvovaginal disorder or agents actively promoting a healthy vagina are still not fully understood. It is an important area of focus.

Maternal and infant factors that shape neonatal gut colonization by bacteria

INTRODUCTION

Early life is a critical developmental window coinciding with the establishment of a community of neonatal gut microbes which are vitally important for immune development. The composition of this microbial community is affected by multiple factors.

AREAS COVERED

The effect of pre-pregnancy and pregnancy maternal health, maternal nutrition, pregnancy disorders such as gestational diabetes, maternal antibiotic usage, delivery mode, infant feeding, and infant antibiotic usage on gut microbial composition are outlined along with the potential impact of associated microbiota differences on infant health.

EXPERT OPINION

Recent developments in understanding what shapes our microbiota indicates that the greatest impact on infant gut microbiota composition during the first year of life is seen with the mode of delivery, infant diet, and infant antibiotic usage. Current data is insufficient to fully establish the role of apparently less important factors such as maternal health on microbiota development although their impact is likely smaller. Technological advances will allow for improved understanding of underlying mechanisms by which specific microbes impact on infant health, which in time will enable full appreciation of the role of the gut microbiota in early life development.

Characterization of aerobic vaginitis in late pregnancy in a Chinese population: A STROBE-compliant study

This study aimed to analyze the clinical characteristics, responsible pathogens, and antibiotic sensitivity of aerobic vaginitis (AV) infection in women in late pregnancy in western China.We enrolled 246 pregnancy with AV (≥35 weeks gestation) and 204 reproductive non-pregnancy with AV from West China between January 2019 and December 2019. Then, bacterial culture, identification and antibiotic sensitivity testing were performed. Subsequently, we retrospectively analyzed the vaginal microbiota of 250 healthy pregnant women with no AV and compared the maternal features and pregnancy outcomes.Regarding bacterial diversity, Streptococcus and Lactobacillus were highly abundant in women with AV in late pregnancy, whereas Staphylococcus spp. and other bacteria were significantly more abundant in reproductive non-pregnant women with AV. In addition, 82.5% (343/416) of the single isolate comprised Escherichia coli, group B Streptococcus, Enterococcus faecalis, and Staphylococcus aureus. Among the top 4 isolates, 13.4% (46/343) were multidrug-resistant, but all isolates were highly susceptible to nitrofurantoin. Escherichia coli was 100% susceptible to amikacin, meropenem, ertapenem, and imipenem (100%, 157/157), and gram-positive cocci were 100% (186/186) susceptible to vancomycin and linezolid. Finally, we found that pregnant women with AV had high rates of histories of vaginitis, premature rupture of membranes and neonatal infection.Our study reveals new insights into AV infection during pregnancy and highlights the different vaginal bacterial microbiome compositions between pregnant and reproductive non pregnant women with AV, these results may translate to treatments that are more cost-effective than current standard treatments.

Comparison of vaginal microbiota in gynecologic cancer patients pre- and post-radiation therapy and healthy women

BACKGROUND

While the importance of commensal microbes in vaginal health is well appreciated, little is known about the effects of gynecological cancer (GynCa) and radiation therapy (RT) on the vaginal microbiome (VM) of postmenopausal women.

METHODS

We studied women with GynCa, pre- (N = 65) and post-RT (N = 25) and a group of healthy controls (N = 67) by sequencing the V4 region of the 16S rRNA gene from vaginal swabs and compared the diversity and composition of VMs between the three groups accounting for potential confounding factors in multivariate analysis of variance.

RESULTS

Comparisons of cancer vs healthy groups revealed that Lactobacillus and Bifidobacterium have significantly higher relative abundance in the healthy group, while the cancer group was enriched in 16 phylogroups associated with bacterial vaginosis (BV) and inflammation, including Sneathia, Prevotella, Peptoniphilus, Fusobacterium, Anaerococcus, Dialister, Moryella, and Peptostreptococcus. In our sample, RT affected the α-diversity and correlated with higher abundance of typically rare VM species, including several members of the Lacnospiraceae family, a taxon previously linked to vaginal dysbiosis. In addition to cancer and treatment modalities, age and vaginal pH were identified as significant parameters that structure the VM.

CONCLUSIONS

This is among the first reports identifying VM changes among postmenopausal women with cancer. RT alone seems to affect several phylogroups (12 bacterial genera), while gynecological cancer and its treatment modalities are associated with even greater significant shifts in the vaginal microbiota including the enrichment of opportunistic bacterial pathogens, which warrants further attention.

Oligosaccharides and Complex Carbohydrates: A New Paradigm for Cranberry Bioactivity

Cranberry is a well-known functional food, but the compounds directly responsible for many of its reported health benefits remain unidentified. Complex carbohydrates, specifically xyloglucan and pectic oligosaccharides, are the newest recognized class of biologically active compounds identified in cranberry materials. Cranberry oligosaccharides have shown similar biological properties as other dietary oligosaccharides, including effects on bacterial adhesion, biofilm formation, and microbial growth. Immunomodulatory and anti-inflammatory activity has also been observed. Oligosaccharides may therefore be significant contributors to many of the health benefits associated with cranberry products. Soluble oligosaccharides are present at relatively high concentrations (~20% w/w or greater) in many cranberry materials, and yet their possible contributions to biological activity have remained unrecognized. This is partly due to the inherent difficulty of detecting these compounds without intentionally seeking them. Inconsistencies in product descriptions and terminology have led to additional confusion regarding cranberry product composition and the possible presence of oligosaccharides. This review will present our current understanding of cranberry oligosaccharides and will discuss their occurrence, structures, ADME, biological properties, and possible prebiotic effects for both gut and urinary tract microbiota. Our hope is that future investigators will consider these compounds as possible significant contributors to the observed biological effects of cranberry.

Rectal Microbiome Composition Correlates with Humoral Immunity to HIV-1 in Vaccinated Rhesus Macaques

There is considerable effort directed toward evaluating HIV-1 vaccine platforms to select the most promising candidates for enhancing mucosal HIV-1 antibody. The most successful thus far, the RV144 trial provided partial protection due to waning HIV-1 antibody titers. In order to develop an effective HIV vaccine, it may therefore be important to understand how biological factors, such as the microbiome, modulate host immune responses. Furthermore, as intestinal microbiota antigens may generate antibodies cross-reactive to the HIV-1 envelope glycoprotein, understanding the relationship between gut microbiota composition and HIV-1 envelope antibody responses after vaccination is important. Here, we demonstrate for the first time in rhesus macaques that the rectal microbiome composition can influence HIV-1 vaccine immunogenicity, and we report temporal changes in the mucosal microbiome profile following HIV-1 vaccination. Our results could inform findings from the HIV Vaccine Trials Network (HVTN) vaccine studies and contribute to an understanding of how the microbiome influences HIV-1 antibody responses.

The microbiome is an integral and dynamic component of the host and is emerging as a critical determinant of immune responses; however, its influence on vaccine immunogenicity is largely not well understood. Here, we examined the pivotal relationship between the mucosal microbiome and vaccine-induced immune responses by assessing longitudinal changes in vaginal and rectal microbiome profiles after intradermal immunization with a human immunodeficiency virus type 1 (HIV-1) DNA vaccine in adult rhesus macaques that received two prior DNA primes. We report that both vaginal and rectal microbiomes were dominated by Firmicutes but were composed of distinct genera, denoting microbiome specialization across mucosal tissues. Following immunization, the vaginal microbiome was resilient, except for a transient decrease in Streptococcus. In contrast, the rectal microbiome was far more responsive to vaccination, exhibiting an increase in the ratio of Firmicutes to Bacteroidetes. Within Bacteroidetes, multiple genera were significantly decreased, including Prevotella, Alloprevotella, Bacteroides, Acetobacteroides, Falsiporphyromonas, and Anaerocella. Decreased abundance of Prevotella correlated with induction of gut-homing α₄β₇⁺ effector CD4 T cells. Prevotella abundance also negatively correlated with rectal HIV-1 specific IgG levels. While rectal Lactobacillus was unaltered following DNA vaccination, baseline Lactobacillus abundance showed strong associations with higher rectal HIV-1 gp140 IgA induced following a protein boost. Similarly, the abundance of Clostridium in cluster IV was associated with higher rectal HIV-1 gp140 IgG responses. Collectively, these data reveal that the temporal stability of bacterial communities following DNA immunization is site dependent and highlight the importance of host-microbiome interactions in shaping HIV-1 vaccine responses. Our findings have significant implications for microbial manipulation as a strategy to enhance HIV vaccine-induced mucosal immunity.

IMPORTANCE There is considerable effort directed toward evaluating HIV-1 vaccine platforms to select the most promising candidates for enhancing mucosal HIV-1 antibody. The most successful thus far, the RV144 trial provided partial protection due to waning HIV-1 antibody titers. In order to develop an effective HIV vaccine, it may therefore be important to understand how biological factors, such as the microbiome, modulate host immune responses. Furthermore, as intestinal microbiota antigens may generate antibodies cross-reactive to the HIV-1 envelope glycoprotein, understanding the relationship between gut microbiota composition and HIV-1 envelope antibody responses after vaccination is important. Here, we demonstrate for the first time in rhesus macaques that the rectal microbiome composition can influence HIV-1 vaccine immunogenicity, and we report temporal changes in the mucosal microbiome profile following HIV-1 vaccination. Our results could inform findings from the HIV Vaccine Trials Network (HVTN) vaccine studies and contribute to an understanding of how the microbiome influences HIV-1 antibody responses.

Exploring profile and potential influencers of vaginal microbiome among asymptomatic pregnant Chinese women

Background

This study was designed to explore the profile and potential influencers of the vaginal microbiome (VMB) among asymptomatic pregnant Chinese women and its possible association with pregnancy outcomes.

Methods

A prospective study was conducted among pregnant Chinese women receiving regular prenatal care at a hospital in Shanghai, China from March 2017 to March 2018. Vaginal swabs were obtained from 113 asymptomatic pregnant women in mid-pregnancy and sequenced by the V3-V4 region of 16S rRNA on an Ion S5™ XL platform. Demographic characteristics and major pregnancy outcomes were collected through questionnaires and electronic medical records.

Results

The predominant vaginal community state types (CSTs) were CST I (45.1%) and CST III (31.9%). Participants were divided into a lactobacilli-dominant group (LD, CST I/II/III/I-III/V, n = 100, 88.5%) and a less lactobacilli-dominant group (LLD, CST IV-A/B, n = 13, 11.5%). Women in the LLD group showed an increased alpha diversity [median (interquartile range, IQR): 2.41 (1.67, 2.49) vs. 0.30 (0.17, 0.59), P < 0.001], which was related to a lower pre-pregnancy body mass index (BMI) (P = 0.012), and a greater instance of passive smoking (P = 0.033). The relative abundance of Lactobacillus was correlated positively with the pre-pregnancy BMI (r = 0.177, P = 0.041), but negatively with passive smoking (r =  - 0.204, P = 0.030).

Conclusion

The vaginal flora of asymptomatic pregnant Chinese women was mostly dominated by Lactobacillus crispatus and L. iners. A lower BMI and greater instance of passive smoking may contribute to a less lactobacilli-dominant VMB. However, a larger sample size is needed.

Characteristics of the vaginal microbiome in cross-border female sex workers in China: a case-control study

Background

Female sex workers (FSWs) are key groups in the transmission of sexual transmitted infections (STI), and vaginal microbiome variations play an important role in transmission. We aimed to explore the characteristics of vaginal microbiome among FSWs.

Materials and Methods

A total of 24 cross-border FSWs were randomly selected from a cross-sectional survey for female sex workers in southwest China. Thirty-seven female non-sex workers (FNSWs) were randomly selected from the gynecology clinic and health examination center. Vaginal swabs were collected, bacterial DNA extracted and 16S rRNA genes were sequenced. Differences in the vaginal microbiome between both groups were compared using bioinformatics analysis.

Results

One DNA sample was excluded due to unqualified concentration, therefore 60 samples were sequenced. FSWs had significantly different vaginal microbiota β diversity, but undifferentiated α diversity when compared with non-sex workers. The average relative abundance of Sneathia, Shigella, Neisseria, Chlamydia, Prevotella, Enterococcus and Ureaplasma among FSWs was higher than FNSWs, and relative abundance of Atopobium in FSWs was lower than FNSWs. The Lactobacillus genus was the major genus in both groups. At the species level, Lactobacllus crispatus, Lactobacllus gasseri and Lactobacllus jensenii, in female sex workers, were lower when compared to FNSWs.

Conclusion

There were distinct differences in vaginal bacteria variety between FSWs and FNSWs. Some disease-related genus were also more abundant in FSWs. Based on these observations, further research is required to identify microbiome communities related to high STI risks and other diseases in these cohorts.

The Bladder is Not Sterile: an Update on the Urinary Microbiome

Purpose of Review

The article discusses (1) techniques used to study bacterial urinary microbiota; (2) existence of non-bacterial urinary microbiota; (3) associations between changes in urinary microbiota and various benign lower urinary tract disorders.

Recent Findings

Urine harbors a diverse microbial community that resides within it. A multitude of studies have identified differences in these communities associated with urologic conditions, suggesting that microbial communities may maintain normal bladder homeostasis. Technological advances in analytic approaches have improved our understanding of the urinary microbiome. The choice of urine sampling method (voided, catheterized, or aspirated) will significantly influence microbiome findings. Sex and age highly influence urinary microbiota; in addition to rigorous inclusion criteria, microbial studies must be sufficiently powered to overcome the substantial interindividual variability of urinary microbiota. Regardless of these complicating factors, studies have identified microbial patterns correlating with both urologic diagnoses and treatment responses.

Summary

Without a clear understanding of the variability of and exogenous influences on the urinary microbiota in the absence of disease, it has been challenging to reveal the microbial patterns responsible for disease pathophysiology. Host mechanisms in response to the urinary microbiome are also poorly understood. Additional research can address whether the manipulation of urinary microbiota will benefit lower urinary tract health.

Vulvovaginitis Caused by Candida Species Following Antibiotic Exposure

PURPOSE OF REVIEW

Goal was to review epidemiology, pathophysiology, and prevention of post-antibiotic Candida vulvovaginitis (VVC).

RECENT FINDINGS

Antibacterial therapy, whether systemic or locally applied to the vagina, represents the single most frequent and predictable cause or triggering mechanism of symptomatic vulvovaginal candidiasis (VVC). Such initiating mechanisms may precipitate sporadic or recurrent episodes of VVC. In spite of this widely recognized association, the exact mechanism whereby antibiotics of all classes cause acute exacerbation of symptomatic vaginal disease remains largely unstudied and therefore largely unknown. Pathophysiology is hypothesized to be reduction or alteration of vaginal microbiome restraints of yeast colonization, proliferation, and expression of virulence characteristics. The predictable link between antibiotic use and post-antibiotic VVC affords practitioners an opportunity for timely intervention using selective, convenient antimycotics usually drugs but possibly probiotic measures. Indications and limitation of these steps are discussed.

Repeated Vaginal Exposures to the Common Cosmetic and Household Preservative Methylisothiazolinone Induce Persistent, Mast Cell-Dependent Genital Pain in ND4 Mice

A history of allergies doubles the risk of vulvodynia—a chronic pain condition of unknown etiology often accompanied by increases in numbers of vulvar mast cells. We previously established the biological plausibility of this relationship in mouse models where repeated exposures to the allergens oxazolone or dinitrofluorobenzene on the labiar skin or inside the vaginal canal of ND4 Swiss Webster outbred mice led to persistent tactile sensitivity and local increases in mast cells. In these models, depletion of mast cells alleviated pain. While exposure to cleaning chemicals has been connected to elevated vulvodynia risk, no single agent has been linked to adverse outcomes. We sensitized female mice to methylisothiazolinone (MI)—a biocide preservative ubiquitous in cosmetics and cleaners—dissolved in saline on their flanks, and subsequently challenged them with MI or saline for ten consecutive days in the vaginal canal. MI-challenged mice developed persistent tactile sensitivity, increased vaginal mast cells and eosinophils, and had higher serum Immunoglobulin E. Therapeutic and preventive intra-vaginal administration of Δ⁹-tetrahydrocannabinol reduced mast cell accumulation and tactile sensitivity. MI is known to cause skin and airway irritation in humans, and here we provide the first pre-clinical evidence that repeated MI exposures can also provoke allergy-driven genital pain.

Does the endometrial cavity have a molecular microbial signature?

Recent molecular studies concluded that the endometrium has a resident microbiota dominated by Lactobacillus spp. and is therefore similar to that of the vagina. These findings were largely derived from endometrial samples obtained through a transcervical catheter and thus prone to contamination. Herein, we investigated the molecular microbial profiles of mid-endometrial samples obtained through hysterectomy and compared them with those of the cervix, vagina, rectum, oral cavity, and controls for background DNA contamination. Microbial profiles were examined through 16S rRNA gene qPCR and sequencing. Universal bacterial qPCR of total 16S rDNA revealed a bacterial load exceeding that of background DNA controls in the endometrium of 60% (15/25) of the study subjects. Bacterial profiles of the endometrium differed from those of the oral cavity, rectum, vagina, and background DNA controls, but not of the cervix. The bacterial profiles of the endometrium and cervix were dominated by Acinetobacter, Pseudomonas, Cloacibacterium, and Comamonadaceae. Both 16S rRNA gene sequencing and Lactobacillus species-specific (L. iners & L crispatus) qPCR showed that Lactobacillus was rare in the endometrium. In conclusion, if there is a microbiota in the middle endometrium, it is not dominated by Lactobacillus as was previously concluded, yet further investigation using culture and microscopy is necessary.

Modulation effect of vaginal mucosal microflora and susceptibility to Neisseria gonorrhoeae infections: a systematic review and meta-analysis

OBJECTIVE

The vaginal microbiota may modulate susceptibility to Neisseria gonorrhea (NG) infections. The objective of this meta-analysis was to evaluate the association between these NG infections and the vaginal microbiota.

METHOD

A systematic review and meta-analysis was conducted to investigate the correlation of vaginal microbiota and NG risk. Primary sources of the reviewed studies were from inception through December 2018. Vaginal mucosa microflora were dichotomized into high-Lactobacillus vaginal microbiota and low-Lactobacillus vaginal microbiota (LL-VMB), using either Nugent score, Amsel's criteria, presence of clue cells or 16S rRNA gene sequencing.

RESULTS

A total of 8 studies qualified for inclusion in this meta-analysis. LL-VMB could be regarded as worse prognostic factor, and the pooled OR was 1.33 (95% CI 1.02, 1.73; P = 0.04, I² = 44%). LL-VMB was associated with a significantly higher susceptibility of NG. Trend for the sensitive analysis was consistence with the primary outcome. Significant publication bias was not detected by the funnel plot.

CONCLUSION

In conclusion, the systematic review and meta-analysis has demonstrated that LL-VMB was significantly associated with a high NG susceptibility.

Fungal-Bacterial Interactions in Health and Disease

Fungi and bacteria encounter each other in various niches of the human body. There, they interact directly with one another or indirectly via the host response. In both cases, interactions can affect host health and disease. In the present review, we summarized current knowledge on fungal-bacterial interactions during their commensal and pathogenic lifestyle. We focus on distinct mucosal niches: the oral cavity, lung, gut, and vagina. In addition, we describe interactions during bloodstream and wound infections and the possible consequences for the human host.