Vaginal Microbiome Is Associated With Vulvodynia, Vulvar Pain Syndrome: A Case-Control Study

Vaginal and rectal microbiome contribute to genital inflammation in chronic pelvic pain

BACKGROUND

Chronic pelvic pain (CPP) is a multifactorial syndrome that can substantially affect a patient's quality of life. Endometriosis is one cause of CPP, and alterations of the immune and microbiome profiles have been observed in patients with endometriosis. The objective of this pilot study was to investigate differences in the vaginal and gastrointestinal microbiomes and cervicovaginal immune microenvironment in patients with CPP and endometriosis diagnosis compared to those with CPP without endometriosis and no CPP.

METHODS

Vaginal swabs, rectal swabs, and cervicovaginal lavages (CVL) were collected among individuals undergoing gynecologic laparoscopy. Participants were grouped based on patients seeking care for chronic pain and/or pathology results: CPP and endometriosis (CPP-Endo) (n = 35), CPP without endometriosis (n = 23), or patients without CPP or endometriosis (controls) (n = 15). Sensitivity analyses were performed on CPP with endometriosis location, stage, and co-occurring gynecologic conditions (abnormal uterine bleeding, fibroids). 16S rRNA sequencing was performed to profile the microbiome, and a panel of soluble immune mediators was quantified using a multiplex assay. Statistical analysis was conducted with SAS, R, MicrobiomeAnalyst, MetaboAnalyst, and QIIME 2.

RESULTS

Significant differences were observed between participants with CPP alone, CPP-Endo, and surgical controls for body mass index, ethnicity, diagnosis of ovarian cysts, and diagnosis of fibroids. In rectal microbiome analysis, both CPP alone and CPP-Endo exhibited lower alpha diversity than controls, and both CPP groups revealed enrichment of irritable bowel syndrome-associated bacteria. CPP-Endo exhibited an increased abundance of vaginal Streptococcus anginosus and rectal Ruminococcus. Patients with CPP and endometrioma (s) demonstrated increased vaginal Streptococcus, Lactobacillus, and Prevotella compared to other endometriosis sites. Further, abnormal uterine bleeding was associated with an increased abundance of bacterial vaginosis-associated bacteria. Immunoproteomic profiles were distinctly clustered by CPP alone and CPP-Endo compared to controls. CPP-Endo was enriched in TNF⍺, MDC, and IL-1⍺.

CONCLUSIONS

Vaginal and rectal microbiomes were observed to differ between patients with CPP alone and CPP with endometriosis, which may be useful in personalized treatment for individuals with CPP and endometriosis from those with other causes of CPP. Further investigation is warranted in patients with additional co-occurring conditions, such as AUB/fibroids, which add additional complexity to these conditions and reveal the enrichment of distinct pathogenic bacteria in both mucosal sites. This study provides foundational microbiome-immunoproteomic knowledge related to chronic pelvic pain, endometriosis, and co-occurring gynecologic conditions that can help improve the treatment of patients seeking care for pain.

Diet influences community dynamics following vaginal group B streptococcus colonization

The vaginal microbiota plays a pivotal role in reproductive, sexual, and perinatal health and disease. Unlike the well-established connections between diet, metabolism, and the intestinal microbiota, parallel mechanisms influencing the vaginal microbiota and pathogen colonization remain overlooked. In this study, we combine a mouse model of Streptococcus agalactiae strain COH1 [group B Streptococcus (GBS)] vaginal colonization with a mouse model of pubertal-onset obesity to assess diet as a determinant of vaginal microbiota composition and its role in colonization resistance. We leveraged culture-dependent assessment of GBS clearance and culture-independent, sequencing-based reconstruction of the vaginal microbiota in relation to diet, obesity, glucose tolerance, and microbial dynamics across time scales. Our findings demonstrate that excessive body weight gain and glucose intolerance are not associated with vaginal GBS density or timing of clearance. Diets high in fat and low in soluble fiber are associated with vaginal GBS persistence, and changes in vaginal microbiota structure and composition due to diet contribute to GBS clearance patterns in nonpregnant mice. These findings underscore a critical need for studies on diet as a key determinant of vaginal microbiota composition and its relevance to reproductive and perinatal outcomes.IMPORTANCEThis work sheds light on diet as a key determinant influencing the composition of vaginal microbiota and its involvement in group B Streptococcus (GBS) colonization in a mouse model. This study shows that mice fed diets with different nutritional composition display differences in GBS density and timing of clearance in the female reproductive tract. These findings are particularly significant given clear links between GBS and adverse reproductive and neonatal outcomes, advancing our understanding by identifying critical connections between dietary components, factors originating from the intestinal tract, vaginal microbiota, and reproductive outcomes.

Is Vulvodynia Associated With an Altered Vaginal Microbiota?: A Systematic Review

INTRODUCTION

Vulvodynia is defined as vulvar pain of at least 3 months' duration, without clear identifiable cause, which may have potential associated factors. It can have a significant impact on women's quality of life due to a combination of physical pain, emotional distress, and limited treatment options. Despite affecting a considerable number of women worldwide, the causes and underlying mechanisms of vulvodynia remain poorly understood. Given the recognized association of the vaginal microbiota with various gynecologic disorders, there has been growing interest in exploring the potential role of the vaginal microbiota in the etiology of vulvodynia. This systematic review aims to evaluate the current literature on the association between the vaginal microbiota and vulvodynia.

MATERIAL AND METHODS

A systematic search of multiple databases, including PubMed, Scopus, Web of Science, Cochrane Library, and Ovid MEDLINE, was conducted to identify relevant peer-reviewed studies up to May 12, 2023. The following search terms were used across these databases: "vulvodynia," "vestibulodynia," "vulvar vestibulitis," "microbiome," "microbiota," and "flora."

RESULTS

A total of 8 case-control studies were included, the quality of which was assessed using the Newcastle-Ottawa Scale. Data extraction and synthesis were performed using a standardized protocol. In most studies, no major differences were found between the vaginal bacterial composition of women with vulvodynia and that of controls. No specific bacterial taxa were consistently associated with vulvodynia. The relationship between vaginal microbiota diversity and vulvodynia remains to be fully understood.

CONCLUSIONS

The role of vaginal microbiota in vulvodynia, if any, remains unclear. Because of the cross-sectional nature of the included studies, it is not possible to make any causal inferences. Further research, using larger and more diverse study populations and advanced sequencing techniques, is necessary to gain a better understanding of the potential relationship between the vaginal microbiota and vulvodynia.

Changes in the Vaginal Microbiota of Women With Secondary Localized Provoked Vulvodynia

OBJECTIVE

The etiology of localized provoked vulvodynia (LPV) remains unknown, but observations suggest the involvement of the vaginal microbiota. We examined the vaginal microbiota of women with LPV and healthy controls, upon after a low-oxalate diet (LOD).

MATERIALS AND METHODS

A total of 9 women diagnosed with secondary LPV and 21 healthy controls were recruited from the Galilee Medical Center in Israel and subjected to prospective evaluations of their vaginal microbiota. Total DNA was extracted from vaginal discharge samples provided before and after following LOD for 3 weeks and was then subjected to 16S sequencing. Data obtained were then used to evaluate α and β diversity, identify differentially abundant bacterial taxa in LPV, and determine their impact on the metabolism.

RESULTS

These evaluations revealed decreased diversity in the vaginal microbiota of women with LPV and identified the Ochrobactrum genus and Pseudomonadaceae family as indicators for LPV. In addition, we identified 23 differentially expressed bacterial metabolic pathways between the LPV and control samples and revealed that LOD could induce changes in the β diversity of LPV vaginal microbiomes, which was further supported by some degree of pain reduction in patients.

CONCLUSIONS

Localized provoked vulvodynia and LOD were associated with shifts in the vaginal microbiota. However, the impact of these changes on the development of LPV requires additional studies with a larger cohort.

Menstrual Cycle Characteristics and Vulvodynia

Objective: The menstrual cycle may influence vulvodynia through hormonal pathways or vulvar irritation due to menstruation or menstrual hygiene. We assessed menstrual cycle characteristics in those with and without clinically confirmed vulvodynia. Materials and Methods: Participants were recruited from the administrative database of a health care network serving ∼27% of Minneapolis-Saint Paul residents. For 220 clinically confirmed cases and 224 controls, menstrual cycle characteristics were retrospectively assessed at three time points: before age 18, the year before onset of vulvar pain, and 3 months before study participation. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between menstrual characteristics at all three time points and vulvodynia. Models adjusted for prespecified confounders were evaluated against crude effect estimates. Results: Women with heavier menstrual flows had higher odds of vulvodynia compared with women with lighter menstrual flows during their adolescent years (OR 1.62, 95% CI 0.91-2.86), the year before onset of vulvar pain (OR = 2.11, 95% CI 1.10-4.02), and during the 3 months before study participation (OR = 1.67, 95% CI 0.91-3.06). Women with more severe cramps also had higher odds of vulvodynia compared with women with no or mild cramps during their adolescent years (OR = 2.45, 95% CI 1.45-4.15), the year before onset of vulvar pain (OR = 3.30, 95% CI 1.67-6.51), and during the 3 months before study participation (OR = 4.96, 95% CI 1.99-12.36). Women with specific premenstrual symptoms also reported higher odds of vulvodynia. Among those with vulvodynia, half reported a change in vulvar pain across the menstrual cycle, with 60% of these reporting greater pain just before and during menstruation. Furthermore, we observe a trend of decreased tampon use and increased use of sanitary pads as women with vulvodynia moved closer to their date of diagnosis. Conclusions: Menstrual cycle characteristics were associated with vulvodynia, and associations were consistent across different phases of the reproductive life cycle.

The Human Vulvar Microbiome: A Systematic Review

The link between cancer and the microbiome is a fast-moving field in research. There is little knowledge on the microbiome in ((pre)malignant) conditions of the vulvar skin. This systematic review aims to provide an overview of the literature regarding the microbiome composition of the healthy vulvar skin and in (pre)malignant vulvar disease. This study was performed according to the PRISMA guidelines. A comprehensive, electronic search strategy was used to identify original research articles (updated September 2021). The inclusion criteria were articles using culture-independent methods for microbiome profiling of the vulvar region. Ten articles were included. The bacterial composition of the vulva consists of several genera including Lactobacillus, Corynebacterium, Staphylococcus and Prevotella, suggesting that the vulvar microbiome composition shows similarities with the corresponding vaginal milieu. However, the vulvar microbiome generally displayed higher diversity with commensals of cutaneous and fecal origin. This is the first systematic review that investigates the relationship between microbiome and vulvar (pre)malignant disease. There are limited data and the level of evidence is low with limitations in study size, population diversity and methodology. Nevertheless, the vulvar microbiome represents a promising field for exploring potential links for disease etiology and targets for therapy.