Contraception: Influence on Vaginal Microbiota and Identification of Vaginal Lactobacilli Using MALDI-TOF MS and 16S rDNA Sequencing

The association between lifestyle factors and the composition of the vaginal microbiota: a review

PURPOSE

The vaginal microbiota offers valuable insights into women's sexual health and the risk of developing sexually transmitted infections (STIs) and bacterial vaginosis. Despite the public health implications of changes in the vaginal environment, existing data on this topic remain sparse.

METHODS

Following the PRISMA statement guidelines, we consulted five bibliographic databases, focusing on five main daily habits and behaviors. We included only studies published up to October 2023, investigating the influence of personal hygiene, sexual behaviors, hormonal contraception, smoking, alcohol consumption, and psychosocial stress on the vaginal microbiota using next-generation sequencing.

RESULTS

Based on our inclusion criteria, we incorporated 37 studies into this review. Hormonal contraception and personal hygiene were found to promote eubiosis of the vaginal microbiota. In contrast, sexual behaviors, smoking, alcohol consumption, and psychosocial stress were associated with an increased susceptibility to bacterial vaginosis, STIs, and severe pelvic inflammatory diseases due to a modified vaginal microbiota. Black ethnicity emerged as a confounding factor, with this population showing unstable vaginal microbiota. Oral contraception and a stable male sexual partner were found to favor Lactobacillus colonization, acting as a protective factor. Conversely, non-hormonal contraception and unprotected or non-penile/vaginal sexual activity increased the incidence of vaginal inflammation and bacterial vaginosis by disturbing the vaginal microbiota and reducing Lactobacillus abundance.

CONCLUSION

Daily habits and lifestyle can influence the composition of the vaginal microbiota, thereby affecting vaginal health. Disturbances in the vaginal microbiota could be associated factors for STIs and vaginosis. Therefore, prioritizing more appropriate management of the vaginal microbiota is crucial.

Inhibiting pathogenicity of vaginal Candida albicans by lactic acid bacteria and MS analysis of their extracellular compounds

Maintaining healthy vaginal microflora post-puberty is critical. In this study we explore the potential of vaginal lactic acid bacteria (LAB) and their extracellular metabolites against the pathogenicity of Candida albicans. The probiotic culture free supernatant (PCFS) from Lactobacillus crispatus, L. gasseri, and L. vaginalis exhibit an inhibitory effect on budding, hyphae, and biofilm formation of C. albicans. LGPCFS manifested the best potential among the LAB PCFS, inhibiting budding for 24 h and restricting hyphae formation post-stimulation. LGPCFS also pre-eminently inhibited biofilm formation. Furthermore, L. gasseri itself grew under RPMI 1640 stimulation suppressing the biofilm formation of C. albicans. The PCFS from the LAB downregulated the hyphal genes of C. albicans, inhibiting the yeast transformation to fungi. Hyphal cell wall proteins HWP1, ALS3, ECE1, and HYR1 and transcription factors BCR1 and CPH1 were downregulated by the metabolites from LAB. Finally, the extracellular metabolome of the LAB was studied by LC-MS/MS analysis. L.gasseri produced the highest antifungal compounds and antibiotics, supporting its best activity against C. albicans. Vaginal LAB and their extracellular metabolites perpetuate C. albicans at an avirulent state. The metabolites produced by these LAB in vitro have been identified, and can be further exploited as a preventive measure against vaginal candidiasis.

Uterine fibroids and longitudinal profiles of the vaginal microbiota in a cohort presenting for transvaginal ultrasound

Bacterial vaginosis, characterized in part by low levels of vaginal Lactobacillus species, has been associated with pro-inflammatory cytokines which could fuel uterine fibroid development. However, prior work on the associations between uterine fibroids and vaginal bacteria is sparse. Most studies have focused on assessment of individual taxa in a single sample. To address research gaps, we sought to compare short, longitudinal profiles of the vaginal microbiota in uterine fibroid cases versus controls with assessment for hormonal contraceptives (HCs), a possible confounder associated with both protection from fibroid development and increases in Lactobacillus-dominated vaginal microbiota. This is a secondary analysis of 83 reproductive-age cisgender women who presented for transvaginal ultrasound (TVUS) and self-collected mid-vaginal swabs daily for 1-2 weeks before TVUS (Range: 5-16 days, n = 697 samples). Sonography reports detailed uterine fibroid characteristics (N = 21 cases). Vaginal microbiota was assessed by 16S rRNA gene amplicon sequencing and longitudinal microbiota profiles were categorized by hierarchical clustering. We compared longitudinal profiles of the vaginal microbiota among fibroid cases and controls with exact logistic regression. Common indications for TVUS included pelvic mass (34%) and pelvic pain (39%). Fibroid cases tended to be older and report Black race. Cases less often reported HCs versus controls (32% vs. 58%). A larger proportion of cases had low-Lactobacillus longitudinal profiles (48%) than controls (34%). In unadjusted analysis, L. iners-dominated and low-Lactobacillus profiles had higher odds of fibroid case status compared to other Lactobacillus-dominated profiles, however these results were not statistically significant. No association between vaginal microbiota and fibroids was observed after adjusting for race, HC and menstruation. Results were consistent when number of fibroids were considered. There was not a statistically significant association between longitudinal profiles of vaginal microbiota and uterine fibroids after adjustment for common confounders; however, the study was limited by small sample size.

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model

Vaginal microbial composition is associated with differential risk of urogenital infection. Although Lactobacillus spp. are thought to confer protection against infection, the lack of in vivo models resembling the human vaginal microbiota remains a prominent barrier to mechanistic discovery. Using 16S rRNA amplicon sequencing of C57BL/6J female mice, we found that vaginal microbial composition varies within and between colonies across three vivaria. Noting vaginal microbial plasticity in conventional mice, we assessed the vaginal microbiome of humanized microbiota mice (HMbmice). Like the community structure in conventional mice, HMbmice vaginal microbiota clustered into community state types but, uniquely, HMbmice communities were frequently dominated by Lactobacillus or Enterobacteriaceae. Compared to conventional mice, HMbmice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia. Although Escherichia and Lactobacillus both correlated with the absence of uterine GBS, vaginal pre-inoculation with exogenous HMbmouse-derived E. coli, but not Ligilactobacillus murinus, reduced vaginal GBS burden. Overall, HMbmice serve as a useful model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens.

Contraceptive effects on the cervicovaginal microbiome: Recent evidence including randomized trials

BACKGROUND

Until recently, most data regarding the effects of non-barrier contraceptives on the mucosal microbiome have derived from observational studies, which are potentially biased due to behavioral confounders that may mask their true biological effects.

METHOD OF STUDY

This narrative review summarises recent evidence of the effect of contraceptives on the cervicovaginal microbiome, emphasising data obtained through randomized trials.

RESULTS

Good quality data describe that initiation of long-acting progestin-only contraceptives, including levonorgestrel (LNG)-implant and the injectables depot-medroxyprogesterone acetate (DMPA-IM) and norethisterone enanthate (NET-EN) do not alter the mucosal microbial environment. Likewise, no strong evidence exists that the use of oral contraceptive pills (OCPs) is associated with alterations of the vaginal microbiome or increased risk of bacterial sexually transmitted infections (STIs). Limited data on the effect of intravaginal rings (IVRs) on the mucosal environment exist and show conflicting effects on the vaginal microbiota. Copper intrauterine device (Cu-IUD) initiation has been associated with bacterial vaginosis (BV) acquisition, including in a randomized trial. LNG-IUDs may have similar affects but need to be evaluated further.

CONCLUSION

Different synthetic hormones have divergent effects on the microbiome and therefore novel hormonal methods need to be rigorously evaluated. Furthermore, the addition of antiretrovirals into multipurpose technologies may alter the effects of the hormonal component. There is thus a critical need to improve our understanding of the biological effects of contraceptive hormones and delivery methods with different pharmacokinetic and chemical properties on the mucosal microbiome in rigorous trials, to inform the development of novel contraceptives and improve individual family planning guidance.

The urinary, vaginal and gut microbiota in women with genital lichen sclerosus - A case-control study

BACKGROUND

Lichen sclerosus (LS) is a chronic, autoimmune skin disease predominantly located in the anogenital region in women. In recent years, the role of the human microbiota in the pathogenesis of autoimmune diseases, including LS, has received interest.

OBJECTIVES

The study aimed to evaluate and compare the composition of the urinary, vaginal and gut microbiota in women with LS versus non-affected controls.

STUDY DESIGN

Women diagnosed with LS (n = 16) and matched controls (n = 14) were enrolled in the study. From each participant, midstream urine, upper and lower vaginal swabs, as well as faecal samples, were collected. The microbiota composition was assessed using 16S ribosomal RNA (rRNA) gene sequencing of the V4 hypervariable region.

RESULTS

We observed no LS-specific clustering in either of the four anatomic niches, using either hierarchical cluster analysis or weighted beta diversity metrics. However, for unweighted UniFrac, significant differences in the urinary and lower vaginal microbiota were observed when comparing women with LS to controls. These findings indicate that while the two groups have microbiota dominated by the same bacteria, variations do occur amongst less abundant bacteria. The LEfSe analysis revealed a higher relative abundance of the genus Streptococcus in the urinary and lower vaginal microbiota in women with LS compared to controls. Additionally, a higher relative abundance of phylum Euryarchaeota was observed in the gut microbiota in women with LS compared to controls.

CONCLUSION

In this study, we demonstrated several differences amongst less abundant bacteria in the urinary, lower vaginal and faecal microbiota when comparing women with LS to controls. However, further research is required to assess whether these microbiota differences are causative or merely a result of the underlying LS disease.

Endometriosis and dysbiosis: State of art

Endometriosis is a complex and heterogeneous disease affecting approximately 10% of reproductive age women. The hypothesis that alterations in the microbiota are involved in the pathogenesis of endometriosis has been postulated. Possible explanations for the implications of dysbiosis in endometriosis include the Bacterial Contamination hypothesis and immune activation, cytokine-impaired gut function, altered estrogen metabolism and signaling. Thus, dysbiosis, disrupt normal immune function, leading to the elevation of proinflammatory cytokines, compromised immunosurveillance and altered immune cell profiles, all of which may contribute to the pathogenesis of endometriosis. The aim of this review is to summarize the available literature data about the relationship between microbiota and endometriosis.

Intravaginal Combination Therapy of Acetic and Lactic Acid in premenopausal women with recurrent vulvovaginal candidiasis: A randomized, double-blind placebo-controlled feasibility trial

BACKGROUND

Recurrent vulvovaginal candidiasis management primarily entails azole therapy used as required or as an extended daily or weekly maintenance therapy for 6 months or more. Unfortunately, relapse within 3-6 months of ceasing maintenance therapy is experienced for more than half the patients, for whom indefinite treatment is required.

OBJECTIVES

To explore the feasibility of trial design examining a prophylaxis treatment to prevent recurrent vulvovaginal candidiasis symptomatic episodes and reduce adverse effects.

STUDY DESIGN

A double-blinded randomized controlled feasibility trial was conducted in Australia. Women with recurrent vulvovaginal candidiasis were enrolled.

METHODS

An intravaginal prophylaxis application of lactic acid and acetic acid (Intravaginal Combination Therapy of Acetic and Lactic Acid) was compared with placebo. Primary outcomes comprised recruitment and retention, compliance to study medications and study assessments. Secondary outcomes included the reduction of symptomatic recurrence over the trial period and the acceptability, satisfaction, safety and tolerability of the intervention. The feasibility of quality-of-life measures was also explored.

RESULTS

Fifteen participants were enrolled and randomized (active = 9, placebo = 6). Consent rate was 23.4%. Eight participants were lost to follow-up (active = 5, placebo = 3). Forty-seven per cent of participants (n = 7) were 100% compliant with the intervention, six of which completed the trial with good assessment compliance. The blinding process was effective. The study demonstrated a reduction in relapse in both active and placebo groups with only four participants across both groups reporting symptomatic episodes while enrolled. The intervention demonstrated good tolerability. Quality-of-life data showed minimal variance with a high quality-of-life measure.

CONCLUSION

This trial assesses the feasibility of conducting a large-scale study exploring the efficacy of the Intravaginal Combination Therapy of Acetic and Lactic Acid intravaginal intervention and hints on the importance of psychological support through appropriate disease-specific communication and clinical attention. Consideration of the reported recruitment challenges, the inclusion of suitable quality-of-life measures and digital data collection is warranted for adaptation to a fully powered trial.

Perspective on the relationship between reproductive tract microbiota eubiosis and dysbiosis and reproductive function

The role played by microbiota is attracting growing attention within the scientific and medical community, in both human and animal fields, in the last years. Most of the studies have been focused on the intestinal microbiome, whilst little attention has been paid to other systems, like the reproductive tract of both females and males. However, there is a growing body of information showing the interplay between reproductive tract dysbiosis, due to the action of pathogens and/or unhealthy lifestyle, and reproductive disease and disorders in many mammalian species. The present review aims to summarise current knowledge on the biodiversity of the microbiota of the reproductive tract, and the possible relationships between eubiosis or dysbiosis and reproductive health and function in both females and males.

Vaginal States: Detection of Conversion Processes in Women Using Contraception and Characterization of Vaginal Lactobacillus Species

BACKGROUND

The vaginal microenvironment, regulated by an immune system, can be protected or altered by many factors, including contraceptive methods.

OBJECTIVE

The objective of this study is to evaluate the impact of contraceptive methods on the basic vaginal states (BVSs) and to identify culturable vaginal Lactobacillus species.

METHODS

This is a prospective, consecutive, longitudinal, and descriptive study. The vaginal contents of 208 women were sampled prior to initiating contraception and six months later. The BVSs were established using the balance of vaginal content (BAVACO) methodology that evaluates microbiota and vaginal inflammatory reaction (VIR). Lactobacillus species were characterized by biochemical tests and mass spectrometry. The following contraceptive methods were evaluated: combined oral contraceptive pill (COCP), condom (CON) and rhythm method (RHYT). McNemar's test was used.

RESULTS

Of the 208 women, 171 attended both examinations. In the COCP group (n=127), 83 vaginal contents maintained a normal microbiota, 1 sample became dysbiotic, and 37/43 dysbiotic microbiota samples reverted to normal (p<0.0001). A conversion to BVS with VIR was detected in the CON group (n=31) (p=0.001). The RHYT group (n=13) maintained its initial BVSs. The predominant Lactobacillus species found were L. crispatus and L. gasseri, with a trend toward a positive association between L. crispatus and COCP (OR=2.82; p=0.058).

CONCLUSION

Hormone administration corrected the dysbiosis and preserved a normal BVS. The CON increased the VIR. The protection of the microbiota observed in the rhythm method probably responds to a systemic hormonal influence. The trend toward a positive association between COCP and L. crispatus, with its protective properties, evidenced an effective hormonal relationship.

An Insight into Vaginal Microbiome Techniques

There is a unique microbial community in the female lower genital tract known as the vaginal microbiota, which varies in composition and density and provides significant benefits during pregnancy, reproductive cyclicity, healthy newborn delivery, protection from preterm birth, infections such as UTIs, bacterial vaginosis, and so on, and improves the efficacy of treatments for vaginal cancers. Methods: It is necessary to know how the vaginal microbiome is composed in order to make an accurate diagnosis of the diseases listed above. A microbiome’s members are difficult to classify, and the way microbial communities function and influence host–pathogen interactions are difficult to understand. More and more metagenomic studies are able to unravel such complexities due to advances in high-throughput sequencing and bioinformatics. When it comes to vaginal microbiota research, we’ll be looking at the use of modern techniques and strategies that can be used to investigate variations in vaginal microbiota in order to detect diseases earlier, better treat vaginal disorders, and boost women’s health. Discussion: The discussed techniques and strategies may improve the treatment of vaginal disorders and may be beneficial for women’s overall health.

Cervical Squamous Intraepithelial Lesions Are Associated with Differences in the Vaginal Microbiota of Mexican Women

Cervical cancer is an important health concern worldwide and is one of the leading causes of death in Mexican women. Previous studies have shown changes in the female genital tract microbe community related to human papillomavirus (HPV) infection and cervical cancer; yet, this link remains unexplored in many human populations. This study evaluated the vaginal bacterial community among Mexican women with precancerous squamous intraepithelial lesions (SIL). We sequenced the V3 region of the 16S rRNA gene in cervical samples from 228 Mexican women, including 121 participants with SIL, most of which were HPV positive, and 107 healthy women without HPV infection or SIL. The presence of SIL was associated with changes in composition (beta diversity) and with a higher species richness (Chao1). A comparison of HPV-positive women with and without SIL showed that microbiota changes occurred even in the absence of SIL. Multivariate association with linear models (MaAsLin) analysis yielded independent associations between HPV infection and an increase in the relative abundance of Brachybacterium conglomeratum and Brevibacterium aureum as well as a decrease in two Lactobacillus iners operational taxonomic units (OTUs). We also identified a positive independent association between HPV-16, the most common HPV subtype linked to SIL, and Brachybacterium conglomeratum. Our work indicates that HPV infection leading to SIL is primarily associated with shifts in vaginal microbiota composition, some of which may be specific to this human population.

IMPORTANCE Human papillomavirus (HPV) plays a critical role in cervical carcinogenesis but is not sufficient for cervical cancer development, indicating the involvement of other factors. The vaginal microbiota is an important factor in controlling infections caused by HPV, and, depending on its composition, it can modulate the microenvironment in vaginal mucosa against viral infections. Ethnic and sociodemographic factors influence differences in vaginal microbiome composition, which underlies the dysbiotic patterns linked to HPV infection and cervical cancer across different populations of women. Here, we provide evidence for associations between vaginal microbiota patterns and HPV infection linked to ethnic and sociodemographic factors. To our knowledge, this is the first report of the species Brevibacterium aureum and Brachybacterium conglomeratum linked to HPV infection or squamous intraepithelial lesions (SIL).

The role of gut and genital microbiota and the estrobolome in endometriosis, infertility and chronic pelvic pain

BACKGROUND

Endometriosis is a chronic, burdensome condition that is historically understudied. Consequently, there is a lack of understanding of the etiology of the disease and its associated symptoms, including infertility and chronic pelvic pain (CPP). Endometriosis development is influenced by estrogen metabolism and inflammation, which are modulated by several factors including the microbiome and the estrobolome (the collection of genes encoding estrogen-metabolizing enzymes in the gut microbiome). Therefore, there is increasing interest in understanding the role of microbiota in endometriosis etiology.

OBJECTIVE AND RATIONALE

To date, there is no cure for endometriosis and treatment options often are ineffective. This manuscript will review the potential relationship between the microbiome and endometriosis, infertility and CPP and highlight the available data on the microbiome in relation to endometriosis and its related symptoms. The overarching goal of this manuscript is to inform future microbiome research that will lead to a deeper understanding of the etiology of the disease and possible diagnostic modalities and treatments. The potential impact of the microbiome on estrogen regulation modulated by the estrobolome, as well as inflammation and other endometriosis-promoting mechanisms within the genital tract, will be reviewed. The methodological limitations of microbiome-related studies will be critically assessed to provide improved guidelines for future microbiome and clinical studies.

SEARCH METHODS

PubMed databases were searched using the following keywords: endometriosis AND microbiome, infertility AND microbiome, pelvic pain AND microbiome, IVF (in-vitro fertilization) AND microbiome, endometriosis AND infertility. Clinical and preclinical animal trials that were eligible for review, and related to microbiome and endometriosis, infertility or CPP were included. All available manuscripts were published in 2002-2021.

OUTCOMES

In total, 28 clinical and 6 animal studies were included in the review. In both human and animal studies, bacteria were enriched in endometriosis groups, although there was no clear consensus on specific microbiota compositions that were associated with endometriosis, and no studies included infertility or CPP with endometriosis. However, bacterial vaginosis-associated bacteria and Lactobacillus depletion in the cervicovaginal microbiome were associated with endometriosis and infertility in the majority (23/28) of studies. Interpretation of endometrial studies is limited owing to a variety of methodological factors, discussed in this review. In addition, metadata outlining antibiotic usage, age, race/ethnicity, menopausal status and timing of sample collection in relation to diagnosis of endometriosis was not consistently reported. Animal studies (6/6) support a bidirectional relationship between the gut microbiota and endometriosis onset and progression.

WIDER IMPLICATIONS

There is evidence that a dysbiotic gut or genital microbiota is associated with multiple gynecologic conditions, with mounting data supporting an association between the microbiome and endometriosis and infertility. These microbiomes likely play a role in the gut-brain axis, which further supports a putative association with the spectrum of symptoms associated with endometriosis, including infertility and CPP. Collectively, this review highlights the demand for more rigorous and transparent methodology and controls, consistency across the field, and inclusion of key demographic and clinical characteristics of disease and comparison participants. Rigorous study designs will allow for a better understanding of the potential role of the microbiome in endometriosis etiology and the relationship to other disorders of the female reproductive tract.

Vaginal Microbiota of the Sexually Transmitted Infections Caused by Chlamydia trachomatis and Trichomonas vaginalis in Women with Vaginitis in Taiwan

The three most common sexually transmitted infections (STIs) are Chlamydia trachomatis (CT), Neisseria gonorrhoeae (GC) and Trichomonas vaginalis (TV). The prevalence of these STIs in Taiwan remains largely unknown and the risk of STI acquisition affected by the vaginal microbiota is also elusive. In this study, a total of 327 vaginal swabs collected from women with vaginitis were analyzed to determine the presence of STIs and the associated microorganisms by using the BD Max CT/GC/TV molecular assay, microbial cultures, and 16S rRNA sequencing. The prevalence of CT, TV, and GC was 10.8%, 2.2% and 0.6%, respectively. A culture-dependent method identified that Escherichia coli and Streptococcus agalactiae (GBS) were more likely to be associated with CT and TV infections. In CT-positive patients, the vaginal microbiota was dominated by L. iners, and the relative abundance of Gardnerella vaginalis (12.46%) was also higher than that in TV-positive patients and the non-STIs group. However, Lactobacillus spp. was significantly lower in TV-positive patients, while GBS (10.11%), Prevotella bivia (6.19%), Sneathia sanguinegens (12.75%), and Gemella asaccharolytica (5.31%) were significantly enriched. Using an in vitro co-culture assay, we demonstrated that the growth of L. iners was suppressed in the initial interaction with TV, but it may adapt and survive after longer exposure to TV. Additionally, it is noteworthy that TV was able to promote GBS growth. Our study highlights the vaginal microbiota composition associated with the common STIs and the crosstalk between TV and the associated bacteria, paving the way for future development of health interventions targeting the specific vaginal bacterial taxa to reduce the risk of common STIs.

The effect of different contraceptive methods on the vaginal microbiome

Introduction: Following a historical overview, the effect of different contraceptive methods on vaginal microbiome has been reviewed and summarized.Areas covered: Effects of combined hormonal contraceptives (oral or vaginal) and of progestin only (injectable and implantable), intrauterine devices/systems (copper- or levonorgestrel-releasing), on vaginal microbiome. In addition, mention is made of vaginal rings releasing antiviral drugs and lactic acid.Expert opinion: The vaginal microbiota (VM) is unique in that it is normally dominated by Lactobacillus species providing a degree of protection against infections; this however may vary, depending on the species and strains of Lactobacillus. Bacterial Vaginosis represents the most common dysbiosis of the VM and its prevalence can be influenced by use of contraception. Available evidence indicates that, under the influence of oral or systemically administered female sex hormones, there is apromotion of vaginal eubiosis, with aprevalence of ahealthy VM in which Lactobacilli predominate.

Estrogen induces shift in abundances of specific groups of the coral microbiome

Synthetic estrogens such as ethinylestradiol (EE2) are persistent micropollutants that are not effectively removed from wastewater by conventional treatments. These contaminants are released into waterbodies, where they disrupt endocrine systems of organisms and cause harmful effects such as feminization, infertility, reproduction problems and genital malformations. The consequences of this pollution for key marine ecosystems such as coral reefs and their associated microbiomes are underexplored. We evaluated the effects of EE2 concentrations of 100 ng L-1 and 100 µg L-1 on the coral metaorganism Mussismilia harttii. The results indicated no effects on visible bleaching or Fv/Fm ratios in the corals during a 17-day microcosm experiment. However, next-generation sequencing of 16S rDNA revealed a statistically significant effect of high EE2 concentrations on OTU richness, and shifts in specific microbial groups after treatments with or without EE2. These groups might be bioindicators of early shifts in the metaorganism composition caused by EE2 contamination.

Gardnerella and vaginal health: the truth is out there

The human vagina is a dynamic ecosystem in which homeostasis depends on mutually beneficial interactions between the host and their microorganisms. However, the vaginal ecosystem can be thrown off balance by a wide variety of factors. Bacterial vaginosis (BV) is the most common vaginal infection in women of childbearing age but its etiology is not yet fully understood, with different controversial theories being raised over the years. What is generally accepted is that BV is often characterized by a shift in the composition of the normal vaginal microbiota, from a Lactobacillus species dominated microbiota to a mixture of anaerobic and facultative anaerobic bacteria. During BV, a polymicrobial biofilm develops in the vaginal microenvironment, being mainly composed of Gardnerella species. The interactions between vaginal microorganisms are thought to play a pivotal role in the shift from health to disease and might also increase the risk of sexually transmitted infections acquisition. Here, we review the current knowledge regarding the specific interactions that occur in the vaginal niche and discuss mechanisms by which these interactions might be mediated. Furthermore, we discuss the importance of novel strategies to fight chronic vaginal infections.

A Randomized Controlled Open Label Crossover Trial to Study Vaginal Colonization of Orally Administered Lactobacillus Reuteri RC-14 and Rhamnosus GR-1 in Pregnant Women at High Risk for Preterm Labor

Lactobacilli administration has been suggested for the treatment and prevention of bacterial vaginosis, which increases the risk for preterm birth. We aimed to evaluate the vaginal colonization of lactobacilli orally administered to pregnant women at risk for preterm birth. We performed a randomized and controlled crossover study between January 2016 and May 2017. Forty pregnant women at high risk for preterm birth with normal vaginal flora (Nugent score ≤ 3) were randomized to either receive two oral capsules/day each containing 5 × 10⁹Lactobacilli (L.) rhamnosus GR-1 and L. reuteri RC-14 (n = 20) or no treatment (n = 20) for 2 months. Treatments were then crossed over for an additional two months. A vaginal examination and swabbing were performed for assessment of bacterial vaginosis at baseline and every month until study completion. At the same time points, vaginal samples were cultured and subjected to matrix-assisted-laser-desorption/ionization-time-of-flight-mass-spectrometry (MALDI TOF-MS) for the detection of the specific bacterial strains contained in the capsules. The primary endpoint was the presence of the administered lactobacilli strains in the vagina during the first two months of follow-up. Thirty-eight women completed the study. During the first two months of treatment, L. rhamnosus GR-1 was detected in one (5%) woman on the probiotic treatment and 2 (11%) women receiving no treatment (p = 0.6). L. rhamnosus GR-1 was detected in vaginal samples of 4 (11%) women during probiotic treatment (of both groups) and L. reuteri RC-14 was not detected in any samples. The rest of the endpoints were not different between the groups. Altogether, vaginal colonization of lactobacilli following oral administration is low during pregnancy.

Molecular Diagnosis of Vaginitis: Comparing Quantitative PCR and Microbiome Profiling Approaches to Current Microscopy Scoring

Vaginitis is often diagnosed by microscopy and limited to testing for bacterial vaginosis (BV), vulvovaginal candidiasis, and trichomoniasis. Approximately 10% of vaginal swabs are negative but designated "altered flora" by BV Nugent score, leaving clinicians unsure how to treat patients. Accurate and comprehensive vaginitis diagnostics are needed to direct treatment and reduce risks of recurrent or more severe infections. Vaginal swabs were collected from 93 women (mean age, 23.53 years; range, 18 to 42 years) in a cross-sectional study. Microscopy results for BV and Candida were compared to those from two molecular approaches: (i) a comprehensive quantitative PCR (qPCR) assay, including testing for aerobic vaginitis (AV), Candida, sexually transmitted infections (STI), and BV (Applied Biosystems) with an accompanying BV interpretive algorithm (Coriell Life Sciences), and (ii) microbiome profiling of the 16S rRNA gene (Illumina). Microscopy plus BV Nugent score had 76% overall agreement with the qPCR plus BV interpretive algorithm method (24 positive, 47 negative). OF the nine samples designated altered flora by Nugent, five were categorized BV positive and four were BV negative by the qPCR method. Although BV negative, 3/4 of the latter samples had positive AV targets with one also was STI positive. Microscopic identification of Candida versus that by qPCR had 94% agreement (9 positive, 78 negative). The comprehensive qPCR assay revealed alternative etiologies summarized as 38% BV, 10% AV, 5% Candida, 2% STI, 10% mixed infection (positive targets in multiple panels), and 35% negative for all targets. 16S microbiome analysis confirmed the bacterial qPCR results and identified differentiating patterns between AV, BV, and Lactobacillus-dominated vaginal microbiomes.