Bacterial vaginosis and season, a proxy for vitamin D status

Bacterial vaginosis: a review of approaches to treatment and prevention

Bacterial vaginosis (BV) is a common cause of vaginitis worldwide and is associated with serious reproductive health outcomes, including increased risk of preterm birth, sexually transmitted infections, and pelvic inflammatory disease. The current and only FDA-approved treatment regimens for BV are antibiotics, such as metronidazole and clindamycin. Antibiotics provide a short-term cure for bacterial vaginosis; however, fail to provide a consistent long-term cure for many women. Fifty to eighty percent of women experience a BV recurrence within a year of completing antibiotic treatment. This may be because after antibiotic treatment, beneficial strains of Lactobacillus, such as L. crispatus, do not recolonize the vagina. In the absence of an effective long-term cure, patients, providers, and researchers are exploring different approaches to treatment and prevention, resulting in a rapid evolution of perspectives on BV pathogenesis and approaches to management. Current areas of investigation for BV management include probiotics, vaginal microbiome transplantation, pH modulation, and biofilm disruption. Behavioral modifications that may help include smoking cessation, condom use and hormonal contraception. Additional strategies considered by many people include dietary modification, non-medical vaginally applied products, choice of lubricant, and treatments from medical practices outside of allopathic medicine. This review aims to provide a comprehensive and up to date outline of the landscape of ongoing and potential treatment and prevention strategies for BV.

Association between bacterial vaginosis and 25-Hydroxy vitamin D: a case-control study

INTRODUCTION

Bacterial vaginosis (BV) is the most common vaginal dysbiosis among women of reproductive age. Micronutrient deficiencies, including vitamin D deficiency, can increase the risk of BV. The findings of previous studies regarding the relationship between vitamin D deficiency and BV were conflicting. Therefore, this study aimed to evaluate the association between BV and serum level of 25-hydroxy vitamin D.

MATERIALS AND METHODS

This case-control study was conducted in Gonabad County in 2021. One hundred and twenty-five confirmed BV cases and 125 controls who were matched based on age and intercourse frequency (maximum difference of two days per week) enrolled in the study. Data collection was performed using a demographic and reproductive data questionnaire and a checklist for recording Whiff test results, serum 25-hydroxy vitamin D level, litmus paper observation, and microscopic findings (clue cells). Serum level of vitamin D was evaluated based on enzyme-linked immunoassay method (Monobind kit) from 0.5 ml venous blood drawn from each participant. The conditional logistic regression model was used to analyze data.

RESULTS

The BV cases had significantly lower 25-hydroxy vitamin D serum levels than controls. The odds of BV increased with vitamin D deficiency (Adjusted odds ratio (AOR): 4.34, 95% confidence interval (CI): 1.39-13.4, p = 0.011, FDR q-value = 0.051), vitamin D insufficiency (AOR: 3.65, 95% CI: 1.23-10.85; p = 0.020; FDR q-value = 0.053), cigarette/hookah smoking (AOR: 3.65, 95% CI: 1.23, 10.85; p = 0.020; FDR q-value = 0.053) and lower age at first intercourse (AOR: 1.16, 95% CI: 1.05, 1.28; p = 0.004; FDR q-value = 0.048). The odds of BV was 0.80 and 0.78 times lower in participants who had coitus interruptus (AOR: 0.20, 95% CI: 0.06, 0.63; p = 0.006; FDR q-value = 0.048) and condom use (AOR: 0.28, 95% CI: 0.10, 0.79; p = 0.016; FDR q-value = 0.051), respectively, compared to participants who did not use contraceptives.

CONCLUSION

These findings suggested that lower serum vitamin D levels were associated with an increased risk of developing BV. However, further studies are needed to confirm the results of the present study.

Vitamin D deficiency increases the risk of bacterial vaginosis during pregnancy: Evidence from a meta-analysis based on observational studies

Background

Bacterial vaginosis (BV) is the most common microbiological syndrome in women of childbearing age, causing numerous adverse health issues in pregnant women. Several observational studies have discussed the association between vitamin D deficiency and the risk of BV during pregnancy, but the results were inconclusive. Therefore, this meta-analysis aimed to explore the association between vitamin D deficiency and BV risk in pregnant women.

Materials and methods

We searched four databases, including PubMed, Embase, Cochrane Library, and Web of Science, from their inception to July 2022. Pooled odds ratios (OR) with corresponding 95% confidence intervals (CI) were estimated using random effects models. Additionally, we conducted subgroup analyses to identify the potential sources of between-study heterogeneity. Sensitivity analysis was performed using the method of exclusion, one study at a time. Publication bias was examined using Egger’s test and funnel plot.

Results

A total of 14 studies from 13 articles including 4,793 participants were eligible for this meta-analysis. The outcome showed that vitamin D deficiency may increase the risk of BV during pregnancy by 54% (OR, 1.54; 95% CI, 1.25–1.91; P < 0.001). In subgroup analyses, positive associations were also found in studies that were: conducted in black women (OR, 1.56; 95% CI, 0.98–2.48; P = 0.060), focused on the first trimester of pregnancy (OR, 2.22; 95% CI, 1.35–3.64; P = 0.002), of high quality (OR, 3.05; 95% CI, 1.26–7.41; P = 0.014), and adjusted for confounders (OR, 1.28; 95% CI, 1.06–1.55; P = 0.012). Sensitivity analysis reported that BV risk during pregnancy resulting from vitamin D deficiency increased by 157% (OR, 2.57; 95% CI, 1.50–4.42; P = 0.001) when removing the first two high-weight studies. Publication bias was observed using Egger’s test (t = 3.43, P = 0.005) and a visual funnel plot.

Conclusion

This meta-analysis showed that vitamin D deficiency is positively associated with the risk of BV during pregnancy. Further high-quality prospective cohort studies are needed to determine whether vitamin D intake reduces the prevalence of BV in pregnant women.

Is prenatal diet associated with the composition of the vaginal microbiome?

BACKGROUND

The vaginal microbiome has been associated with adverse pregnancy outcomes, but information on the impact of diet on microbiome composition is largely unexamined.

OBJECTIVE

To estimate the association between prenatal diet and vaginal microbiota composition overall and by race.

METHODS

We leveraged a racially diverse prenatal cohort of North Carolina women enrolled between 1995 and 2001 to conduct this analysis using cross-sectional data. Women completed food frequency questionnaires about diet in the previous 3 months and foods were categorised into subgroups: fruits, vegetables, nuts/seeds, whole grains, low-fat dairy, sweetened beverages and red meat. We additionally assessed dietary vitamin D, fibre and yogurt consumption. Stored vaginal swabs collected in mid-pregnancy were sequenced using 16S taxonomic profiling. Women were categorised into three groups based on predominance of species: Lactobacillus iners, Lactobacillus miscellaneous and Bacterial Vaginosis (BV)-associated bacteria. Adjusted Poisson models with robust variance estimators were run to assess the risk of being in a specific vagitype compared to the referent. Race-stratified models (Black/White) were also run.

RESULTS

In this study of 634 women, higher consumption of dairy was associated with increased likelihood of membership in the L. crispatus group compared to the L. iners group in a dose-dependent manner (risk ratio quartile 4 vs. 1: 2.01, 95% confidence interval 1.36, 2.95). Increased intake of fruit, vitamin D, fibre and yogurt was also associated with increased likelihood of membership in L. crispatus compared to L. iners, but only among black women. Statistical heterogeneity was only detected for fibre intake. There were no detected associations between any other food groups or risk of membership in the BV group.

CONCLUSIONS

Higher consumption of low-fat dairy was associated with increased likelihood of membership in a beneficial vagitype, potentially driven by probiotics.

Current and emerging pharmacotherapy for recurrent bacterial vaginosis

INTRODUCTION

Given the frequency of recurrent bacterial vaginosis (RBV), enhancing treatment and preventing recurrence have become the central target of pharmacotherapy today. Antimicrobial failure is occurring at a time when knowledge of pathogenesis of bacterial vaginosis (BV) and RBV is incomplete, limiting rational treatment modification.

AREAS COVERED

The current manuscript reviews pathogenesis of RBV and the performance of available antimicrobials as well as attempts employed to enhance activity and pharmacologic strategies to reduce BV recurrence and refractory vaginal disease. The authors also provide their expert perspectives on the subject area, including their outlook for the future.

EXPERT OPINION

In the face of an empty pipeline of new antibiotics, strategies have emerged to enhance existing antibiotic efficacy, which include modifying drug dose, treatment duration, long-term prophylactic regimens, and use of biofilm disrupting agents. It is likely that future effective therapy will include several simultaneous and consecutive treatment components, including combinations of antibiotics, antibiofilm agents, and probiotics. Measures to prevent sexual transmission and reinfection are also essential.

Reviewing the Composition of Vaginal Microbiota: Inclusion of Nutrition and Probiotic Factors in the Maintenance of Eubiosis

The vaginal microbiota has importance in preserving vaginal health and defending the host against disease. The advent of new molecular techniques and computer science has allowed researchers to discover microbial composition in depth and associate the structure of vaginal microbial communities. There is a consensus that vaginal flora is grouped into a restricted number of communities, although the structure of the community is constantly changing. Certain Community-State Types (CSTs) are more associated with poor reproductive outcomes and sexually transmitted diseases (STDs) meanwhile, CSTs dominated by Lactobacillus species—particularly Lactobacillus crispatus—are more related to vaginal health. In this work, we have reviewed how modifiable and non-modifiable factors may affect normal vaginal microbiota homeostasis—including sexual behavior, race or ethnicity, and hygiene. Special interest has been given to how the use of probiotics, diet intake, and use of hormone replacement therapies (HRTs) can potentially impact vaginal microbiota composition.

Associations between dietary micronutrient intake and molecular-Bacterial Vaginosis

OBJECTIVES

Bacterial vaginosis (BV), a clinical condition characterized by decreased vaginal Lactobacillus spp., is difficult to treat. We examined associations between micronutrient intake and a low-Lactobacillus vaginal microbiota as assessed by molecular methods (termed "molecular-BV").

METHODS

This cross-sectional analysis utilized data collected at the baseline visit of the Hormonal Contraception Longitudinal Study, a cohort of reproductive-aged women followed over 2 years while initiating or ceasing hormonal contraception (HC). The Block Brief 2000 Food Frequency Questionnaire was administered and micronutrient intakes were ranked. Vaginal microbiota composition was assessed using 16S rRNA gene amplicon sequencing and clustered into community state types (CSTs) based on the types and relative abundance of bacteria detected. Associations between the lowest estimated quartile intake of nutrients and having a low-Lactobacillus CST (molecular-BV) were evaluated by logistic regression. Separate models were built for each nutrient controlling for age, body mass index, behavioral factors, HC use and total energy intake. We also conducted a literature review of existing data on associations between micronutrient intakes and BV.

RESULTS

Samples from 104 women were included in this analysis. Their mean age was 25.8 years (SD 4.3), 29.8% were African American, 48.1% were using HC, and 25% had molecular-BV. In adjusted multivariable analyses, the lowest quartile of betaine intake was associated with an increased odds of molecular-BV (aOR 9.2, p value < 0.01, [CI 2.4-35.0]).

CONCLUSIONS

This is the first study to assess the association between estimated micronutrient intake and molecular-BV. Lower energy-adjusted intake of betaine was associated with an increased risk of molecular-BV. Betaine might have direct effects on the vaginal microenvironment or may be mediated through the gut microbiota. Additional research is needed to determine reproducibility of this finding and whether improved intake of select micronutrients such as betaine decreases the risk of BV and its sequelae.

Serum 25-Hydroxyvitamin D and Risk of Self-Reported Bacterial Vaginosis in a Prospective Cohort Study of Young African American Women

BACKGROUND

Bacterial vaginosis (BV), the leading cause of vaginal discharge, is associated with multiple adverse health outcomes; however, its etiology is unknown. BV treatment is not very effective, thus prevention approaches are needed. Studies investigating the impact of vitamin D on the risk of BV have had mixed findings, including two studies reporting increased risk of recurrent BV for women with higher vitamin D.

MATERIALS AND METHODS

Participants were nonpregnant women in a prospective fibroid study of African Americans (ages 23-34 years) from the Detroit area. The exposure was seasonally adjusted annual mean serum 25-hydroxyvitamin D [25(OH)D] at enrollment. The outcome was self-reported doctor-diagnosed BV over ∼20 months between baseline and follow-up. Multivariable-adjusted binomial regression models estimated the risk of BV for a doubling of 25(OH)D and sufficient (≥20 ng/mL) versus deficient (<20 ng/mL) 25(OH)D.

RESULTS

In total, 1459 women were included. Median 25(OH)D was 15.2 ng/mL and 73% were deficient. Sixteen percent of participants reported BV diagnoses over follow-up, 78% of whom had recurrent BV. In multivariable-adjusted analyses, a doubling of 25(OH)D was associated with an increased, rather than the hypothesized decreased, risk of self-reported BV (risk ratio [RR] 1.22, 95% confidence interval 1.02-1.48). Sufficient women also had a significantly higher, rather than lower, risk of self-reported BV (RR 1.31). Results were robust to sensitivity analyses, and post hoc analyses showed no evidence of reverse causation.

CONCLUSIONS

Overall, our findings do not support vitamin D deficiency as a risk factor for BV in these young, nonpregnant African American women.

Vaginal Microbiome and Its Relationship to Behavior, Sexual Health, and Sexually Transmitted Diseases

The vaginal microbiota has great significance in maintaining vaginal health and protecting the host from disease. Recent advances in molecular techniques and informatics allow researchers to explore microbial composition in detail and to compare the structure of vaginal microbial communities with behavior and health outcomes, particularly acquisition and transmission of sexually transmitted diseases (STDs) and poor birth outcomes. Vaginal flora have been found to cluster into a limited number of communities, although community structure is dynamic. Certain community types are more associated with poor reproductive outcomes and STDs; communities dominated by Lactobacillus species, particularly Lactobacillus crispatus, are most associated with vaginal health. Modifiable and nonmodifiable factors are strongly associated with community composition, including behavior, race or ethnicity, and hygiene. In this review, we describe the state of the science on the vaginal microbiome and its relationship to behavior, sexual health, and STDs, including determinants of the microbiome that go beyond an individual level.

Role of Vitamin D in urogenital health of geriatric participants

INTRODUCTION

Role of Vitamin D is very well known for the functioning of many body organs. However, its role in the postmenopausal women in relation to various genitourinary disorders has been recognized recently. The main objective of this study was to evaluate role of Vitamin D in vaginal health, prolapse, bladder and bowel function, and bacterial vaginosis (BV).

MATERIALS AND METHODS

This was a randomized controlled study in which 200 geriatric female patients of 65-78 years of age divided into two groups comprising study and control group with 100 participants in each. Detailed obstetrical, gynecological, and clinical history was elicited. Detailed examination regarding the prolapse, urinary and bowel functions, and bacterial infections was done followed by follow-up of 3 and 6 months each. Chi-square and independent t-test used for data analysis.

RESULTS

Mean modified vaginal health index (MVHI) among patients with pelvic floor diseases was statistically significant with P = 0.0472. There was a visible increasing trend in Vitamin D deficiency with increase in time since menopause (P = 0.1193). Patients with pelvic floor disease had mean Vitamin D statistically significant with P = 0.0462. With increase in Vitamin D levels, MVHI was found to be better. The association of mean Vitamin D levels among patients with urinary incontinence as compared to controls was significant with P = 0.0460. Association of mean Vitamin D levels in patients with fecal incontinence and BV as compared to controls was not statistically significant with P = 0.6304 and 0.79, respectively. Low Vitamin D levels were associated with high mean parathyroid hormone (PTH) levels statistically significant with P = 0.034. MVHI was found to increase significantly with Vitamin D supplementation at 3 and 6 months' follow-up. There was increase in Vitamin D and calcium levels and fall in serum PTH levels at 3 and 6 months.

CONCLUSIONS

Vitamin D levels were associated with a decreased risk of pelvic floor disorders, improved MVHI in women in geriatric age group.

Serum vitamin D status and bacterial vaginosis prevalence and incidence in Zimbabwean women

BACKGROUND

Bacterial vaginosis, a highly prevalent vaginal condition, is correlated with many adverse reproductive outcomes. In some studies, low vitamin D status (measured as serum 25-hydroxyvitamin D, 25[OH]D) has been associated with increased prevalence of bacterial vaginosis.

OBJECTIVES

We examined the cross-sectional association between vitamin D status and prevalence of bacterial vaginosis, separately for pregnant and nonpregnant women. Using prospectively collected data, we also characterized the effect of time-varying vitamin D status on incident bacterial vaginosis.

STUDY DESIGN

We quantified 25(OH)D in stored sera collected quarterly from 571 Zimbabwean women participating in the Hormonal Contraception and Risk of HIV Acquisition Study. The analysis was restricted to women not using hormonal contraception. We characterized associations between vitamin D insufficiency (defined as 25[OH]D ≤ 30 ng/mL vs > 30 ng/mL) and prevalence of bacterial vaginosis among nonpregnant women at the enrollment visit and among pregnant women at the first follow-up visit that pregnancy was detected. Among women who were negative for bacterial vaginosis at enrollment (n = 380), we also assessed the effect of time-varying vitamin D status on incident bacterial vaginosis. We used the Liaison 25(OH)D total assay to measure 25(OH)D. Bacterial vaginosis was diagnosed via Nugent score.

RESULTS

At enrollment, the prevalence of bacterial vaginosis was 31% and overall median 25(OH)D was 29.80 ng/mL (interquartile range, 24.70-34.30 ng/mL): 29.75 ng/mL (interquartile range, 25.15-33.95 ng/mL) among women with bacterial vaginosis, and 29.90 ng/mL (interquartile range, 24.70-34.50 ng/mL) among women without bacterial vaginosis. Among pregnant women, the prevalence of bacterial vaginosis was 27% and overall median 25(OH)D was 29.90 ng/mL (interquartile range, 24.10-34.00 ng/mL): 30.80 ng/mL (interquartile range, 26.10-36.90 ng/mL) among women with bacterial vaginosis, and 29.10 ng/mL (interquartile range, 23.80-33.45 ng/mL) among women without bacterial vaginosis. Vitamin D levels ≤ 30 ng/mL were not associated with a prevalence of bacterial vaginosis in nonpregnant women (adjusted prevalence ratio, 1.04; 95% confidence interval, 0.81-1.34) or pregnant women (adjusted prevalence ratio, 0.88, 95% confidence interval, 0.51-1.54). Vitamin D levels ≤ 30 ng/mL were similarly not associated with incident bacterial vaginosis (adjusted hazard ratio, 0.98, 95% confidence interval, 0.73-1.31). Our findings were robust to alternative specifications of vitamin D status including using a cut point for vitamin D deficiency of < 20 ng/mL vs ≥ 20 ng/mL and modeling 25(OH)D as a continuous variable.

CONCLUSION

Among reproductive-age Zimbabwean women, insufficient vitamin D was not associated with increased bacterial vaginosis prevalence or incidence. Given established associations between bacterial vaginosis and poor reproductive outcomes, identification of factors leading to high bacterial vaginosis prevalence is urgently needed.

Antimicrobial resistance genes and modelling of treatment failure in bacterial vaginosis: clinical study of 289 symptomatic women

Clinical management of bacterial vaginosis (BV) is difficult owing to inaccurate diagnostic tests, limited drug choices, and a high rate of recurrence. To our knowledge, there has not been a previous study of antimicrobial resistance (AMR) genes in community practice using next-generation sequencing (NGS). A case-control study (1 : 1 age-matched with and without BV) was undertaken in a series of 326 nongravid women of reproductive age with symptoms of BV to determine the prevalence of AMR genes. NGS was used to describe the complete vaginal microbiota and identify bacterial genes associated with resistance to: macrolides and/or lincosamides - ermA, ermB, ermC, erM, ermTR and mefA; tetracyclines, β-lactams, streptomycin, gentamicin and/or tobramycin - acrA, acrB, mecA, tet, tetA, tolC and aac2; 5-nitroimadazoles - nim and nimB; and triazoles - cdr1 and mdr1. An evidence base was created to inform treatment decisions applicable to individual patients. AMR genes were identified in all drug classes: macrolides, 35.2 %; lincosamides, 35.6 %; tetracyclines, 21.8 %; aminoglycosides (streptomycin, gentamicin and tobramycin), 5.2 % each; 5-nitroimidazoles, 0.3 %; and triazoles, 18.7 %. There was more than a fourfold-higher frequency of AMR genes in pathogens from BV than from non-BV patients for macrolides (58.2 versus 12.3 %, respectively), lincosamides (58.9 versus 12.3 %) and tetracyclines (35.6 versus 8.0 %) (Fisher's exact test; all p < 0.001). For each patient with BV, the spectrum of resistance genes was matched to the pathogens present. AMR genes were present in the majority of vaginal microbiomes of patients with symptoms of BV.

A blinded, randomized controlled trial of high-dose vitamin D supplementation to reduce recurrence of bacterial vaginosis

OBJECTIVE

Low serum vitamin D levels have been associated with increased prevalence of the reproductive tract condition bacterial vaginosis (BV). The objective of this trial was to evaluate the effect of high-dose vitamin D supplementation on BV recurrence.

STUDY DESIGN

This randomized, placebo-controlled, double-blinded trial enrolled 118 women with symptomatic BV from an urban sexually transmitted disease clinic (clinicaltrials.gov registration NCT01450462). All participants received 500 mg of oral metronidazole twice daily for 7 days. Intervention participants (n = 59) also received 9 doses of 50,000 IU of cholecalciferol (vitamin D3) over 24 weeks; control women (n = 59) received matching placebo. Recurrent BV was assessed via Nugent scoring after 4, 12, and 24 weeks. We assessed the effect of the intervention using an intention-to-treat approach, fitting Cox proportional hazards models to evaluate recurrent BV over the follow-up period.

RESULTS

Most participants (74%) were black, with a median age of 26 years. Median presupplementation serum 25-hydroxyvitamin D [25(OH)D] was similar across randomization arms: 16.6 ng/mL in the vitamin D arm and 15.8 ng/mL in the control arm. At trial completion, median 25(OH)D among women receiving vitamin D was 30.5 ng/mL, vs 17.8 ng/mL in control women; 16% of women receiving vitamin D and 57% receiving placebo remained vitamin D deficient (<20 ng/mL). BV prevalence among women randomized to vitamin D was very similar to those randomized to placebo at the 4- and 12-week visits, but by the 24-week visit, BV prevalence was 65% among women in the vitamin D arm and 48% among control women. BV recurrence was not reduced by vitamin D supplementation (intention-to-treat hazard ratio, 1.11; 95% confidence interval, 0.68-1.81). Among women experiencing recurrent BV, median time to recurrence was 13.7 weeks in the vitamin D arm and 14.3 weeks in the control arm.

CONCLUSION

Women receiving vitamin D experienced significant increases in serum 25(OH)D, but this increase was not associated with decreased BV recurrence in this high-risk sexually transmitted disease clinic population.