Vaginal biogenic amines: biomarkers of bacterial vaginosis or precursors to vaginal dysbiosis?

Bacterial vaginosis (BV) is the most common vaginal disorder among reproductive age women. One clinical indicator of BV is a "fishy" odor. This odor has been associated with increases in several biogenic amines (BAs) that may serve as important biomarkers. Within the vagina, BA production has been linked to various vaginal taxa, yet their genetic capability to synthesize BAs is unknown. Using a bioinformatics approach, we show that relatively few vaginal taxa are predicted to be capable of producing BAs. Many of these taxa (Dialister, Prevotella, Parvimonas, Megasphaera, Peptostreptococcus, and Veillonella spp.) are more abundant in the vaginal microbial community state type (CST) IV, which is depleted in lactobacilli. Several of the major Lactobacillus species (L. crispatus, L. jensenii, and L. gasseri) were identified as possessing gene sequences for proteins predicted to be capable of putrescine production. Finally, we show in a small cross sectional study of 37 women that the BAs putrescine, cadaverine and tyramine are significantly higher in CST IV over CSTs I and III. These data support the hypothesis that BA production is conducted by few vaginal taxa and may be important to the outgrowth of BV-associated (vaginal dysbiosis) vaginal bacteria

Recent Advances in Understanding the Microbiology of the Female Reproductive Tract and the Causes of Premature Birth

Data derived from molecular microbiological investigations of the human vagina have led to the discovery of resident bacterial communities that exhibit marked differences in terms of species composition. All undergo dynamic changes that are likely due to intrinsic host and behavioral factors. Similar types of bacteria have been found in both amniotic fluid and the vagina, suggesting a potential route of colonization. Given that not all of the species involved in intrauterine infections are readily cultivated, it is important that culture-independent methods of analysis must be used to understand the etiology of these infections. Further research is needed to establish whether an ascending pathway from the vagina to the amniotic cavity enables the development of intrauterine infections

Association between cigarette smoking and the vaginal microbiota: a pilot study

Smoking has been identified in observational studies as a risk factor for bacterial vaginosis (BV), a condition defined in part by decimation of Lactobacillus spp. The anti-estrogenic effect of smoking and trace amounts of benzo[a]pyrene diol epoxide (BPDE) may predispose women to BV. BPDE increases bacteriophage induction in Lactobacillus spp. and is found in the vaginal secretions of smokers. We compared the vaginal microbiota between smokers and non-smokers and followed microbiota changes in a smoking cessation pilot study. In 2010–2011, 20 smokers and 20 non-smokers were recruited to a cross-sectional study (Phase A) and 9 smokers were enrolled and followed for a 12-week smoking cessation program (Phase B). Phase B included weekly behavioral counseling and nicotine patches to encourage smoking cessation. In both phases, participants self-collected mid-vaginal swabs (daily, Phase B) and completed behavioral surveys. Vaginal bacterial composition was characterized by pyrosequencing of barcoded 16S rRNA genes (V1-V3 regions). Vaginal smears were assigned Nugent Gram stain scores. Smoking status was evaluated (weekly, Phase B) using the semi-quantitative NicAlert® saliva cotinine test and carbon monoxide (CO) exhalation. In phase A, there was a significant trend for increasing saliva cotinine and CO exhalation with elevated Nugent scores (P value <0.005). Vaginal microbiota clustered into three community state types (CSTs); two dominated by Lactobacillus (L. iners, L. crispatus), and one lacking significant numbers of Lactobacillus spp. and characterized by anaerobes (termed CST-IV). Women who were observed in the low-Lactobacillus CST-IV state were 25-fold more likely to be smokers than those dominated by L. crispatus (aOR: 25.61, 95 % CI: 1.03-636.61). Four women completed Phase B. One of three who entered smoking cessation with high Nugent scores demonstrated a switch from CST-IV to a L.iners-dominated profile with a concomitant drop in Nugent scores which coincided with completion of nicotine patches. The other two women fluctuated between CST-IV and L. iners-dominated CSTs. The fourth woman had low Nugent scores with L. crispatus-dominated CSTs throughout. Smokers had a lower proportion of vaginal Lactobacillus spp. compared to non-smokers. Smoking cessation should be investigated as an adjunct to reducing recurrent BV. Larger studies are needed to confirm these findings.https://doi.org/10.1186/1471-2334-14-47

Vaginal cytokine profile and microbiota before and after lubricant use compared with condomless vaginal sex: a preliminary observational study

Limited data suggest that personal lubricants may damage the vaginal mucosal epithelium, alter the vaginal microbiota, and increase inflammation. We compared vaginal cytokine profiles and microbiota before and after vaginal lubricant use and condomless vaginal sex. Reproductive-age women were recruited to a 10-week observational cohort study and were asked to self-collect vaginal samples and behavioral diaries daily. This nested case–control analysis utilized samples collected before and after self-reported condomless sexual activity with lubricants (22 case participants) and without lubricants (22 control participants). Controls were matched to cases on race/ethnicity. Microbiota composition was characterized by sequencing amplicons of the 16S rRNA gene V3–V4 regions. Cytokine concentrations were quantified using a magnetic bead 41-plex panel assay and read using a Bio-Plex 200 array reader. Wilcoxon signed-rank tests were used to assess baseline differences in vaginal cytokines between cases and controls as well as differences pre- and post-exposure. Linear mixed effects models were used to examine differences in relative post-to-pre change in each individual cytokine between matched cases and controls. Similar analyses were conducted for the microbiota data. Mean age was 29.8 years (SD 6.8), and 63.6% were African American. There were few statistically significant changes in cytokines or microbiota before and after exposure in cases or controls. In mixed-effects modeling, the mean relative post-to-pre change of cytokines was higher in cases vs. controls for macrophage derived chemokine (MDC) (p = 0.03). The microbiota data revealed no significant changes when measured by similarity scores, diversity indexes and descriptive community state types (CST) transition analyses. However, post sexual activity, the mean relative abundance of L. crispatus decreased for those who used lubricants (particularly those who were L. iners-dominated prior to exposure). Although there were overall few differences in the vaginal microbiota and cytokine profiles of lubricant users and controls before and after condomless vaginal sex, there was a trend toward decreases in relative abundance of L. crispatus following use of lubricant. Future larger studies that take into account osmolarity and composition of lubricants may provide additional insights.https://doi.org/10.1186/s12879-021-06512-

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

Comparison of Storage Conditions for Human Vaginal Microbiome Studies

BACKGROUND: The effect of storage conditions on the microbiome and metabolite composition of human biological samples has not been thoroughly investigated as a potential source of bias. We evaluated the effect of two common storage conditions used in clinical trials on the bacterial and metabolite composition of the vaginal microbiota using pyrosequencing of barcoded 16S rRNA gene sequencing and (1)H-NMR analyses. METHODOLOGY/PRINCIPAL FINDINGS: Eight women were enrolled and four mid-vaginal swabs were collected by a physician from each woman. The samples were either processed immediately, stored at -80°C for 4 weeks or at -20°C for 1 week followed by transfer to -80°C for another 4 weeks prior to analysis. Statistical methods, including Kolmogorovo-Smirnov and Wilcoxon tests, were performed to evaluate the differences in vaginal bacterial community composition and metabolites between samples stored under different conditions. The results showed that there were no significant differences between samples processed immediately after collection or stored for varying durations. (1)H-NMR analysis of the small molecule metabolites in vaginal secretions indicated that high levels of lactic acid were associated with Lactobacillus-dominated communities. Relative abundance of lactic acid did not appear to correlate with relative abundance of individual Lactobacillus sp. in this limited sample, although lower levels of lactic acid were observed when L. gasseri was dominant, indicating differences in metabolic output of seemingly similar communities. CONCLUSIONS/SIGNIFICANCE: These findings benefit large-scale, field-based microbiome and metabolomic studies of the vaginal microbiota

Prospective studies of vaginal douching and bacterial vaginosis

Limited data are available describing the effects of vaginal douching on vaginal flora, and the key determinants for why women douche are not well understood and have not been studied prospectively. This dissertation research will evaluate the risk for bacterial vaginosis (BV) in a douching cessation trial and explore the longitudinal patterns of vaginal douching in an observational prospective study. Study #1: Methods. Thirty-nine reproductive-age women who reported use of vaginal douche products were enrolled into a 20-week study consisting of a 4-week douching observation phase followed by a 12-week douching cessation phase. Participants then chose to either resume douching or continue cessation (4 weeks). Self-collected vaginal samples were obtained twice-weekly in the first 16 weeks and one sample was collected in week 20. BV was diagnosed by Nugent's Gram stain score ≥ 7. Conditional logistic regression was used to evaluate the individual-level effect of douching cessation on the risk of BV. Results. The adjusted odds ratio (aOR) for BV in douching cessation compared to the douching observation phase was 0.76 (95% CI: 0.33-1.76). Among women who reported that their primary reason for douching was to clean after menstruation, BV was significantly reduced during douching cessation (aOR: 0.23; 95% CI: 0.12-0.44). Study #2: Methods. Non-pregnant women (n=3620) were assessed quarterly for one year at 12 public clinics in Alabama. Conditional logistic regression was applied in a case-crossover analysis to determine the individual-level factors that vary between a woman's douching and non-douching intervals. Findings were compared to a population-level analysis utilizing generalized estimating equations. Results. The case-crossover analysis indicated a woman was more likely to douche when reporting “fishy” vaginal odor (OR:2.74; 95% CI:1.55-4.84), vaginal irritation (OR:1.52; 95% CI:1.10-2.11), summer month (OR:1.37, 95% CI:1.13-1.67) or increase in number of sex partners (≥3, OR:2.42, 95% CI:1.11-5.26). BV/trichomoniasis treatment (OR:0.72, 95% CI:0.59-0.89) and absent menses (OR:0.37, 95% CI:0.28-0.50) were negatively associated with douching. These odds ratios were farther from the null than comparable population-level estimates. Conclusion. Vaginal douching after menstruation may contribute to disruption of vaginal flora. Predictors of feminine hygiene practice can be utilized in developing douching cessation and prevention interventions

Differential sexual network connectivity offers a parsimonious explanation for population-level variations in the prevalence of bacterial vaginosis: a data-driven, model-supported hypothesis

CITATION: Kenyon, C. R., Delva, W. & Brotman, R. M. 2019. Differential sexual network connectivity offers a parsimonious explanation for population-level variations in the prevalence of bacterial vaginosis : a datadriven, model-supported hypothesis. BMC Women's Health, 19:8, doi:10.1186/s12905-018-0703-0.The original publication is available at https://bmcwomenshealth.biomedcentral.comBackground: The prevalence of bacterial vaginosis (BV) and vaginal microbiota types varies dramatically between different populations around the world. Understanding what underpins these differences is important, as highdiversity microbiotas associated with BV are implicated in adverse pregnancy outcomes and enhanced susceptibility to and transmission of sexually transmitted infections. Main text: We hypothesize that these variations in the vaginal microbiota can, in part, be explained by variations in the connectivity of sexual networks. We argue: 1) Couple-level data suggest that BV-associated bacteria can be sexually transmitted and hence high sexual network connectivity would be expected to promote the spread of BVassociated bacteria. Epidemiological studies have found positive associations between indicators of network connectivity and the prevalence of BV; 2) The relationship between BV prevalence and STI incidence/prevalence can be parsimoniously explained by differential network connectivity; 3) Studies from other mammals are generally supportive of the association between network connectivity and high-diversity vaginal microbiota. Conclusion: To test this hypothesis, we propose a combination of empirical and simulation-based study designs.https://bmcwomenshealth.biomedcentral.com/articles/10.1186/s12905-018-0703-0Publisher's versio