A Narrative Review of Current Challenges in the Diagnosis and Management of Bacterial Vaginosis

The cAMP receptor protein from Gardnerella vaginalis is not regulated by ligands

Overgrowth of Gardnerella vaginalis causes an imbalance in vaginal microecology. The pathogenicity of G. vaginalis is directly regulated by the cAMP receptor protein (CRP). In this study, we resolve the crystal structure of CRPGv at a resolution of 2.22 Å and find some significant differences from homologous proteins. The first 23 amino acids of CRPGv are inserted into the ligand binding pocket, creating a strong steric barrier to ligand entry that has not been seen previously in its homologues. In the absence of ligands, the two α helices used by CRPGv to bind oligonucleotide chains are exposed and can specifically bind TGTGA-N6-TCACA sequences. cAMP and other ligands of CRP homologs are not cofactors of CRPGv. There is no coding gene of the adenylate cyclase, and cAMP could not be identified in G. vaginalis by liquid chromatography tandem mass spectrometry. We speculate that CRPGv may achieve fine regulation through a conformational transformation different from that of its homologous proteins, and this conformational transformation is no longer dependent on small molecules, but may be aided by accessory proteins. CRPGv is the first discovered CRP that is not ligand-regulated, and its active conformation provides a structural basis for drug screening.

An updated study of the relationship between bacterial infections and women's immune system, focusing on bacterial compositions with successful pregnancy

Genital tract infections can cause a variety of harmful health outcomes, including endometritis, bacterial vaginosis, and pelvic inflammatory disease, in addition to infertility. Anaerobic bacteria, such as Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae, are more commonly identified in cases of bacterial vaginosis than lactobacilli. It is unknown how the microorganisms that cause pelvic inflammatory diseases and endometritis enter the uterus. Both prospective and retrospective research have connected pelvic inflammatory disorders, chronic endometritis, and bacterial vaginosis to infertility. Similar to bacterial vaginosis, endometritis-related infertility is probably caused by a variety of factors, such as inflammation, immune system recognition of sperm antigens, bacterial toxins, and a higher risk of STDs. Preconception care for symptomatic women may include diagnosing and treating pelvic inflammatory disease, chronic endometritis, and bacterial vaginosis before conception to optimize the results of both natural and assisted reproduction.

Evaluation of the activity of antimicrobial peptides against bacterial vaginosis

New drugs for the treatment of bacterial vaginosis (BV) are yet to be developed due to concerns that they may contribute to the increase in antibiotic resistance in BV. Antimicrobial peptides (AMPs) are one of the most promising options for next-generation antibiotics. In this study, we investigated the bacteriostatic activity of the AMPs Pexiganan, plectasin, melittin, and cathelicidin-DM against Gram-negative and Gram-positive bacteria both in vitro and in a mouse model of BV infection. The results showed that Pexiganan, melittin, and cathelicidin-DM had significant antibacterial activity against both Gram-negative and Gram-positive bacteria. AMPs have great potential for clinical application in the treatment of vaginitis, and this study provides an experimental basis for their use in the active immunoprophylaxis of BV.

Sexual transmission of urogenital bacteria: whole metagenome sequencing evidence from a sexual network study

Sexual transmission of the urogenital microbiota may contribute to adverse sexual and reproductive health outcomes. The extent of sexual transmission of the urogenital microbiota is unclear as prior studies largely investigated specific pathogens. We used epidemiologic data and whole metagenome sequencing to characterize urogenital microbiota strain concordance between participants of a sexual network study. Individuals who screened positive for genital Chlamydia trachomatis were enrolled and referred their sexual contacts from the prior 60-180 days. Snowball recruitment of sexual contacts continued for up to four waves. Vaginal swabs and penile urethral swabs were collected for whole metagenome sequencing. We evaluated bacterial strain concordance using inStrain and network analysis. We defined concordance as ≥99.99% average nucleotide identity over ≥50% shared coverage; we defined putative sexual transmission as concordance between sexual contacts with <5 single-nucleotide polymorphisms per megabase. Of 138 participants, 74 (54%) were female; 120 (87%) had genital chlamydia; and 43 (31%) were recruited contacts. We identified 115 strain-concordance events among 54 participants representing 25 bacterial species. Seven events (6%) were between sexual contacts including putative heterosexual transmission of Fannyhessea vaginae, Gardnerella leopoldii, Prevotella amnii, Sneathia sanguinegens, and Sneathia vaginalis (one strain each), and putative sexual transmission of Lactobacillus iners between female contacts. Most concordance events (108, 94%) were between non-contacts, including eight female participants connected through 18 Lactobacillus crispatus and 3 Lactobacillus jensenii concordant strains, and 14 female and 2 male participants densely interconnected through 52 Gardnerella swidsinskii concordance events.IMPORTANCEEpidemiologic evidence consistently indicates bacterial vaginosis (BV) is sexually associated and may be sexually transmitted, though sexual transmission remains subject to debate. This study is not capable of demonstrating BV sexual transmission; however, we do provide strain-level metagenomic evidence that strongly supports heterosexual transmission of BV-associated species. These findings strengthen the evidence base that supports ongoing investigations of concurrent male partner treatment for reducing BV recurrence. Our data suggest that measuring the impact of male partner treatment on F. vaginae, G. leopoldii, P. amnii, S. sanguinegens, and S. vaginalis may provide insight into why a regimen does or does not perform well. We also observed a high degree of strain concordance between non-sexual-contact female participants. We posit that this may reflect limited dispersal capacity of vaginal bacteria coupled with individuals' comembership in regional transmission networks where transmission may occur between parent and child at birth, cohabiting individuals, or sexual contacts.

A manifold-based framework for studying the dynamics of the vaginal microbiome

The vaginal microbiome plays a crucial role in our health. The composition of this community can be classified into five community state types (CSTs), four of which are primarily consisted of Lactobacillus species and considered healthy, while the fifth features non-Lactobacillus populations and signifies a disease state termed Bacterial vaginosis (BV), which is associated with various symptoms and increased susceptibility to diseases. Importantly, however, the exact mechanisms and dynamics underlying BV development are not yet fully understood, including specifically possible routes from a healthy to a BV state. To address this gap, this study set out to characterize the progression from healthy- to BV-associated compositions by analyzing 8026 vaginal samples and using a manifold-detection framework. This approach, inspired by single-cell analysis, aims to identify low-dimensional trajectories in the high-dimensional composition space. It further orders samples along these trajectories and assigns a score (pseudo-time) to each analyzed or new sample based on its proximity to the BV state. Our results reveal distinct routes of progression between healthy and BV states for each CST, with pseudo-time scores correlating with community diversity and quantifying the health state of each sample. Several BV indicators can also be successfully predicted based on pseudo-time scores, and key taxa involved in BV development can be identified using this approach. Taken together, these findings demonstrate how manifold detection can be used to successfully characterize the progression from healthy Lactobacillus-dominant populations to BV and to accurately quantify the health condition of new samples along the route of BV development.

Development of 3D-printed vaginal devices containing metronidazole for alternative bacterial vaginosis treatment

Bacterial vaginosis (BV) is an abnormal condition caused by the change of microbiota in the vagina. One of the most common bacteria found in the case of BV is Gardnerella vaginalis, which is categorised as anaerobic facultative bacteria. Currently, the available treatment for BV is the use of antibiotics, such as metronidazole (MTZ), in topical and oral dosage forms. The limitation of the currently available treatment is that multiple administration is required and thus, the patient needs to apply the drug frequently to maintain the drug efficacy. To address these limitations, this research proposed prolonged delivery of MTZ in the form of intravaginal devices made from biodegradable and biocompatible polymers. Semi-solid extrusion (SSE) 3D printing was used to prepare the intravaginal devices. The ratio of high and low molecular weight poly(caprolactone) (PCL) was varied to evaluate the effect of polymer composition on the drug release. The versatility of SSE 3D printer was used to print the intravaginal devices into two different shapes (meshes and discs) and containing two different polymer layers made from PCL and a copolymer of methyl vinyl ether and maleic anhydride (Gantrez™-AN119), which provided mucoadhesive properties. Indeed, this layer made from Gantrez™-AN119 increased ca. 5 times the mucoadhesive properties of the final 3D-printed devices (from 0.52 to 2.57 N). Furthermore, MTZ was homogenously dispersed within the polymer matrix as evidenced by scanning electron microscopy analysis. Additionally, in vitro drug release, and antibacterial activity of the MTZ-loaded intravaginal devices were evaluated. Disc formulations were able to sustain the release of MTZ for 72 h for formulations containing 70/30 and 60/40 ratio of high molecular weight/low molecular weight PCL. On the other hand, the discs containing a 50/50 ratio of high molecular weight/low molecular weight PCL showed up to 9 days of release. However, no significant differences in the MTZ release from the MTZ-loaded meshes (60/40 and 50/50 ratio of high molecular weight/low molecular weight PCL) were found after 24 h. The results showed that the different ratios of high and low molecular weight PCL did not significantly affect the MTZ release. However, the shape of the devices did influence the release of MTZ, showing that larger surface area of the meshes provided a faster MTZ release. Moreover, MTZ loaded 3D-printed discs (5% w/w) were capable of inhibiting the growth of Gardnerella vaginalis. These materials showed clear antimicrobial properties, exhibiting a zone of inhibition of 19.0 ± 1.3 mm. Based on these findings, the manufactured represent a valuable alternative approach to the current available treatment, as they were able to provide sustained release of MTZ, reducing the frequency of administration and thus improving patient compliance.

Mesh and layered electrospun fiber architectures as vehicles for Lactobacillus acidophilus and Lactobacillus crispatus intended for vaginal delivery

Bacterial vaginosis (BV) is a recurrent condition that affects millions of women worldwide. The use of probiotics is a promising alternative or an adjunct to traditional antibiotics for BV prevention and treatment. However, current administration regimens often require daily administration, thus contributing to low user adherence and recurrence. Here, electrospun fibers were designed to separately incorporate and sustain two lactic acid producing model organisms, Lactobacillus crispatus (L. crispatus) and Lactobacillus acidophilus (L. acidophilus). Fibers were made of polyethylene oxide and polylactic-co-glycolic acid in two different architectures, one with distinct layers and the other with co-spun components. Degradation of mesh and layered fibers was evaluated via mass loss and scanning electron microscopy. The results show that after 48 h and 6 days, cultures of mesh and layered fibers yielded as much as 108 and 109 CFU probiotic/mg fiber in total, respectively, with corresponding daily recovery on the order of 108 CFU/(mg·day). In addition, cultures of the fibers yielded lactic acid and caused a significant reduction in pH, indicating a high level of metabolic activity. The formulations did not affect vaginal keratinocyte viability or cell membrane integrity in vitro. Finally, mesh and layered probiotic fiber dosage forms demonstrated inhibition of Gardnerella, one of the most prevalent and abundant bacteria associated with BV, respectively resulting in 8- and 6.5-log decreases in Gardnerella viability in vitro after 24 h. This study provides initial proof of concept that mesh and layered electrospun fiber architectures developed as dissolving films may offer a viable alternative to daily probiotic administration.

A Manifold-Based Framework for Studying the Dynamics of the Vaginal Microbiome

The vaginal bacterial community plays a crucial role in preventing infections. The composition of this community can be classified into five main groups, termed community state types (CSTs). Four of these CSTs, which are primarily consisted of Lactobacillus species, are considered healthy, while the fifth, which is composed of non-Lactobacillus populations, is considered less protective. This latter CST is often considered to represent a state termed Bacterial vaginosis (BV) - a common disease condition associated with unpleasant symptoms and increased susceptibility to sexually transmitted diseases. However, the exact mechanisms underlying BV development are not yet fully understood, including specifically, the dynamics of the vaginal microbiome in BV, and the possible routes it may take from a healthy to a BV state. This study aims to identify the progression from healthy Lactobacillus-dominant populations to symptomatic BV by analyzing 8,026 vaginal samples and using a manifold-detection framework. This approach is inspired by single-cell analysis and aims to identify low-dimensional trajectories in the high-dimensional composition space. This framework further order samples along these trajectories and assign a score (pseudo-time) to each sample based on its proximity to the BV state. Our results reveal distinct routes of progression between healthy and BV state for each CST, with pseudo-time scores correlating with community diversity and quantifying the health state of each sample. BV indicators, including Nugent score, positive Amsel's test, and several Amsel's criteria, can also be successfully predicted based on pseudo-time scores. Additionally, Gardnerella vaginalis can be identified as a key taxon in BV development using this approach, with increased abundance in samples with high pseudo-time, indicating an unhealthier state across all BV-development routes on the manifold. Taken together, these findings demonstrate how manifold detection can be used to successfully characterizes the progression from healthy Lactobacillus-dominant populations to BV and to accurately quantify the health condition of new samples along the route of BV development.

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.

Intravaginal lactic acid gel versus oral metronidazole for treating women with recurrent bacterial vaginosis: the VITA randomised controlled trial

BACKGROUND

Bacterial vaginosis is a common and distressing condition for women. Short-term antibiotic treatment is usually clinically effective, but recurrence is common. We assessed the effectiveness of intravaginal lactic acid gel versus oral metronidazole for treating recurrent bacterial vaginosis.

METHODS

We undertook an open-label, multicentre, parallel group, randomised controlled trial in nineteen UK sexual health clinics and a university health centre. Women aged ≥ 16 years, with current bacterial vaginosis symptoms and a preceding history of bacterial vaginosis, were randomised in a 1:1 ratio using a web-based minimisation algorithm, to 400 mg twice daily oral metronidazole tablets or 5 ml once daily intravaginal lactic acid gel, for 7 days. Masking of participants was not possible. The primary outcome was participant-reported resolution of symptoms within 2 weeks. Secondary outcomes included time to first recurrence of symptoms, number of recurrences and repeat treatments over 6 months and side effects.

RESULTS

Five hundred and eighteen participants were randomised before the trial was advised to stop recruiting by the Data Monitoring Committee. Primary outcome data were available for 79% (204/259) allocated to metronidazole and 79% (205/259) allocated to lactic acid gel. Resolution of bacterial vaginosis symptoms within 2 weeks was reported in 70% (143/204) receiving metronidazole versus 47% (97/205) receiving lactic acid gel (adjusted risk difference -23·2%; 95% confidence interval -32.3 to -14·0%). In those participants who had initial resolution and for whom 6 month data were available, 51 of 72 (71%) women in the metronidazole group and 32 of 46 women (70%) in the lactic acid gel group had recurrence of symptoms, with median times to first recurrence of 92 and 126 days, respectively. Reported side effects were more common following metronidazole than lactic acid gel (nausea 32% vs. 8%; taste changes 18% vs. 1%; diarrhoea 20% vs. 6%, respectively).

CONCLUSIONS

Metronidazole was more effective than lactic acid gel for short-term resolution of bacterial vaginosis symptoms, but recurrence is common following both treatments. Lactic acid gel was associated with fewer reported side effects.

TRIAL REGISTRATION

ISRCTN14161293 , prospectively registered on 18th September 2017.

Fabrication and characterization of bioprints with Lactobacillus crispatus for vaginal application

Bacterial vaginosis (BV) is characterized by low levels of lactobacilli and overgrowth of potential pathogens in the female genital tract. Current antibiotic treatments often fail to treat BV in a sustained manner, and > 50% of women experience recurrence within 6 months post-treatment. Recently, lactobacilli have shown promise for acting as probiotics by offering health benefits in BV. However, as with other active agents, probiotics often require intensive administration schedules incurring difficult user adherence. Three-dimensional (3D)-bioprinting enables fabrication of well-defined architectures with tunable release of active agents, including live mammalian cells, offering the potential for long-acting probiotic delivery. One promising bioink, gelatin alginate has been previously shown to provide structural stability, host compatibility, viable probiotic incorporation, and cellular nutrient diffusion. This study formulates and characterizes 3D-bioprinted Lactobacillus crispatus-containing gelatin alginate scaffolds for gynecologic applications. Different weight to volume (w/v) ratios of gelatin alginate were bioprinted to determine formulations with highest printing resolution, and different crosslinking reagents were evaluated for effect on scaffold integrity via mass loss and swelling measurements. Post-print viability, sustained-release, and vaginal keratinocyte cytotoxicity assays were conducted. A 10:2 (w/v) gelatin alginate formulation was selected based on line continuity and resolution, while degradation and swelling experiments demonstrated greatest structural stability with dual genipin and calcium crosslinking, showing minimal mass loss and swelling over 28 days. 3D-bioprinted L. crispatus-containing scaffolds demonstrated sustained release and proliferation of live bacteria over 28 days, without impacting viability of vaginal epithelial cells. This study provides in vitro evidence for 3D-bioprinted scaffolds as a novel strategy to sustain probiotic delivery with the ultimate goal of restoring vaginal lactobacilli following microbiological disturbances.

Epidemiologic Evidence on the Role of Lactobacillus iners in Sexually Transmitted Infections and Bacterial Vaginosis: A Series of Systematic Reviews and Meta-Analyses

ABSTRACT

Although Lactobacillus crispatus -dominated vaginal microbiotas are thought to protect against bacterial vaginosis (BV) and sexually transmitted infections, the role of Lactobacillus iners -dominated microbiotas is less clear. To better understand the impact of L. iners on common cervicovaginal infections, we conducted systematic reviews of the associations between L. iners compared with L. crispatus and 8 outcomes: Chlamydia trachomatis (Ct), BV, human papillomavirus, cervical dysplasia, human immunodeficiency virus, genital herpes, Trichomonas vaginalis , and Neisseria gonorrhoeae . On April 30, 2021, we searched PubMed, Embase, Cochrane Library, and Web of Science for epidemiologic studies of reproductive-age, nonpregnant, cisgender women that used marker gene sequencing to characterize vaginal microbiota composition and presented an effect estimate for the association between L. iners , compared with L. crispatus , and outcomes of interest. For outcomes with ≥3 eligible results presenting the same form of effect estimate, we conducted random-effects meta-analysis. The review protocol was registered prospectively (PROSPERO CRD42020214775). Six Ct studies were included in meta-analysis, which showed L. iners -dominated microbiotas were associated with 3.4-fold higher odds of Ct compared with L. crispatus -dominated microbiotas (95% confidence interval, 2.1-5.4). Three BV studies were included in meta-analysis, which indicated L. iners -dominated microbiotas were associated with 2.1-fold higher prevalence of BV compared with L. crispatus -dominated microbiotas (95% confidence interval, 0.9-4.9). Evidence was too sparse to perform meta-analysis for the remaining outcomes. L. iners -dominated vaginal microbiotas may be suboptimal compared with L. crispatus -dominated microbiotas for BV and Ct. These reviews highlight evidence gaps regarding the remaining outcomes and opportunities to improve epidemiologic rigor in vaginal microbiome science.

Metabolic Network Models of the Gardnerella Pangenome Identify Key Interactions with the Vaginal Environment

Gardnerella is the primary pathogenic bacterial genus present in the polymicrobial condition known as bacterial vaginosis (BV). Despite BV's high prevalence and associated chronic and acute women's health impacts, the Gardnerella pangenome is largely uncharacterized at both the genetic and functional metabolic levels. Here, we used genome-scale metabolic models to characterize in silico the Gardnerella pangenome metabolic content. We also assessed the metabolic functional capacity in a BV-positive cervicovaginal fluid context. The metabolic capacity varied widely across the pangenome, with 38.15% of all reactions being core to the genus, compared to 49.60% of reactions identified as being unique to a smaller subset of species. We identified 57 essential genes across the pangenome via in silico gene essentiality screens within two simulated vaginal metabolic environments. Four genes, gpsA, fas, suhB, and psd, were identified as core essential genes critical for the metabolic function of all analyzed bacterial species of the Gardnerella genus. Further understanding these core essential metabolic functions could inform novel therapeutic strategies to treat BV. Machine learning applied to simulated metabolic network flux distributions showed limited clustering based on the sample isolation source, which further supports the presence of extensive core metabolic functionality across this genus. These data represent the first metabolic modeling of the Gardnerella pangenome and illustrate strain-specific interactions with the vaginal metabolic environment across the pangenome. IMPORTANCE Bacterial vaginosis (BV) is the most common vaginal infection among reproductive-age women. Despite its prevalence and associated chronic and acute women's health impacts, the diverse bacteria involved in BV infection remain poorly characterized. Gardnerella is the genus of bacteria most commonly and most abundantly represented during BV. In this paper, we use metabolic models, which are a computational representation of the possible functional metabolism of an organism, to investigate metabolic conservation, gene essentiality, and pathway utilization across 110 Gardnerella strains. These models allow us to investigate in silico how strains may differ with respect to their metabolic interactions with the vaginal-host environment.

Miniaturized Polymeric Systems for the Intravaginal Gene Therapies: Recent Update on Unconventional Delivery

The prevalence of vaginal infection is increasing among women, especially at reproductive age. For proper eradication of infection, the effective concentration of a drug is required at the infection site. Therefore, local delivery is recommended to exert a direct therapeutic effect at the site action that causes a reduction in dose and side effects. The main focus of vaginal drug delivery is to enhance retention time and patient compliance. The high recurrence rate of vaginal infection due to the lack of effective treatment strategies opens the door for new therapeutic approaches. To combat these setbacks, intravaginal gene therapies have been investigated. High attention has been gained by vaginal gene therapy, especially for sexually transmitted infection treatment. Despite much research, no product is available in the market, although in vitro and preclinical data support the vaginal route as an effective route for gene administration. The main focus of this review is to discuss the recent advancement in miniaturized polymeric systems for intravaginal gene therapies to treat local infections. An overview of different barriers to vaginal delivery and challenges of vaginal infection treatment are also summarised.

High-Throughput Sequencing-Based Analysis of Changes in the Vaginal Microbiome during the Disease Course of Patients with Bacterial Vaginosis: A Case-Control Study

Background: The vaginal microbiome is closely associated with the onset and recurrence of bacterial vaginosis (BV). In the present study, the state of vaginal microbiota during the onset and post-treatment asymptomatic stages of BV were compared to that of a healthy population to evaluate the changes in different characteristic bacteria during the onset, progression, and remission of BV. Methods: A case−control study was performed to explore these changes. Women with clinical symptoms of BV were divided into the disease group (M) and case−control group (C) based on the Nugent score. Subjects in the disease group whose symptoms were resolved after the treatment were assigned to the treated group (T) and healthy subjects were recruited into the normal control (N) group. The V3−V4 hypervariable regions of bacterial 16S rRNA genes were sequenced on the Illumina MiSeq platform. Results: The N harbored the highest number of detected species and a higher abundance of microbiota; they had a significantly higher abundance of Lactobacillus and different bacterial community composition compared to the other three groups. In group M, Gardnerella vaginalis was the dominant species, whereas Lactobacillus iners was predominant in the other three groups. While Lactobacillus was more commonly present in Group C compared to group M. it was significantly increased in group T. Alpha diversity analysis of bacterial communities revealed significant differences in community richness and diversity among all four groups (p < 0.05). Significant differences in the distribution of various bacterial communities among the different groups were also observed (p < 0.05). Specifically, the abundance of eight bacterial taxa (Megasphaera, Aerococcus christensenii, Clostridiales, Gardnerella, Peptostreptococcus, Veillonellaceae, Akkermansia, Coriobacteriales) differed significantly among the four groups (p < 0.05). Conclusion: Significant differences in the composition and alpha diversity of the vaginal microbiota at different stages of BV and the distribution of bacterial communities were observed among the investigated groups. In addition to Gardnerella, Sneathia sanguinegens and Prevotella timonensis play an important role in the pathogenesis of BV. The appearance of BV-like clinical symptoms was closely associated with the decrease in Prevotella and Atopobium vaginae populations.

Bacterial Vaginosis: A Comprehensive Narrative on the Etiology, Clinical Features, and Management Approach

Due to the intricate balance of the vaginal microbiota's ecology, bacterial vaginosis is documented in one-third of females globally at various times of their lives. It is a typical reason for unusual vaginal discharge and is linked to various health problems. Gardnerella vaginalis is one of the anaerobic microorganisms linked to bacterial vaginosis. bacterial vaginosis is diagnosed by Amsel's criteria as well as comparisons among Amsel's criteria, Nugent's criteria, and Hay/Ison's criteria. To scan and assess the degree of dysbiosis within the vaginal microbiome, researchers have upped their game by combining cutting-edge molecular methods, with a focus on how specific microbial populations fluctuate in comparison to a healthy condition. A clue cell can be detected on a simple wet mount of vaginal secretions. Despite receiving regular antibiotic therapy, a substantial risk of treatment failure and bacterial vaginosis recurrence persists. Researchers have revealed positive treatment effects and reduced the infection of the female reproductive system with harmful bacteria.

Screening and characterization of vaginal fluid donations for vaginal microbiota transplantation

Bacterial vaginosis (BV), the overgrowth of diverse anaerobic bacteria in the vagina, is the most common cause of vaginal symptoms worldwide. BV frequently recurs after antibiotic therapy, and the best probiotic treatments only result in transient changes from BV-associated states to "optimal" communities dominated by a single species of Lactobacillus. Therefore, additional treatment strategies are needed to durably alter vaginal microbiota composition for patients with BV. Vaginal microbiota transplantation (VMT), the transfer of vaginal fluid from a healthy person with an optimal vaginal microbiota to a recipient with BV, has been proposed as one such alternative. However, VMT carries potential risks, necessitating strict safety precautions. Here, we present an FDA-approved donor screening protocol and detailed methodology for donation collection, storage, screening, and analysis of VMT material. We find that Lactobacillus viability is maintained for over six months in donated material stored at - 80 °C without glycerol or other cryoprotectants. We further show that species-specific quantitative PCR for L. crispatus and L. iners can be used as a rapid initial screening strategy to identify potential donors with optimal vaginal microbiomes. Together, this work lays the foundation for designing safe, reproducible trials of VMT as a treatment for BV.

Secnidazole: a treatment for trichomoniasis in adolescents and adults

INTRODUCTION

Single-dose 2-g oral secnidazole (SEC), newly approved by the U.S. Food and Drug administration (FDA) for treatment of trichomoniasis, is a potent 5-nitroimidazole with selective toxicity against various micro-organisms. It has been used internationally to treat trichomoniasis, bacterial vaginosis, and other infections for decades. Trichomoniasis is the most common non-viral sexually transmitted infection worldwide and is associated with significant morbidity. In comparison to the only other FDA-approved treatments for trichomoniasis in the United States - metronidazole and tinidazole - SEC has favorable pharmacokinetics, including a longer half-life and a lower minimal lethal concentration.

AREAS COVERED

This work summarizes the chemistry and pharmacology of SEC and reviews the evidence on its efficacy, tolerability, and safety for the treatment of trichomoniasis.

EXPERT OPINION

SEC is an efficacious, well tolerated, and safe treatment for patients aged ≥12 years with trichomoniasis. Single-dose administration makes it a favorable treatment option, especially in cases where adherence to multi-dose treatment regimens may be low.

Exploiting the Anti-Biofilm Effect of the Engineered Phage Endolysin PM-477 to Disrupt In Vitro Single- and Dual-Species Biofilms of Vaginal Pathogens Associated with Bacterial Vaginosis

Bacterial vaginosis (BV) is the most frequent vaginal infection in women of reproductive age. It is caused by the overgrowth of anaerobic vaginal pathogens, such as Gardnerella vaginalis, Fannyhessea vaginae, and Prevotella bivia, which are vaginal pathogens detected during the early stages of incident BV and have been found to form multi-species biofilms. Treatment of biofilm-associated infections, such as BV, is challenging. In this study, we tested the role of an investigational engineered phage endolysin, PM-477, in the eradication of dual-species biofilms composed of G. vaginalis–F. vaginae or G. vaginalis–P. bivia. Single-species biofilms formed by these species were also analysed as controls. The effect of PM-477 on biomass and culturability of single- and dual-species biofilms was assessed in vitro using a microtiter plate assay, epifluorescence microscopy, confocal laser scanning microscopy, and quantitative PCR. The results showed that PM-477 was particularly effective in the disruption and reduction of culturability of G. vaginalis biofilms. In dual-species biofilms, PM-477 exhibited lower efficiency but was still able to selectively and significantly eliminate G. vaginalis. Since polymicrobial interactions have been shown to strongly affect the activity of various antibiotics, the activity of PM-477 in dual-species biofilms is a potentially promising result that should be further explored, aiming to completely eradicate multi-species biofilms associated with BV.

Secnidazole for Trichomoniasis in Women and Men

INTRODUCTION

Secnidazole (SEC), newly FDA-approved for trichomoniasis, is a potent 5-nitroimidazole with selective toxicity against various infections. It has been used internationally to treat trichomoniasis, bacterial vaginosis, and other infections for decades. Trichomoniasis is the most common non-viral sexually transmitted infection worldwide and is associated with significant morbidity. In comparison to the only other approved treatments for trichomoniasis in the U.S.-metronidazole and tinidazole-SEC has favorable pharmacokinetics, including a longer half-life, and a lower minimal lethal concentration against Trichomonas vaginalis.

OBJECTIVES

Provide an updated, comprehensive review of the literature evaluating SEC as a treatment for trichomoniasis in women and men.

METHODS

We conducted a search to identify existing research on SEC and trichomoniasis. On August 6, 2021, we searched MEDLINE using the terms "secnidazole" and "trichomon.*" We excluded reviews, editorials, case reports, and small case series.

RESULTS

We identified 29 articles; 14 of which were included: 5 reported in vitro pharmacologic data on SEC, 6 were observational studies, and 4 were controlled clinical trials (1 observational study also reported in vitro pharmacologic data). Six studies reported data on women only, 1 on men only, and 3 on women and men. These studies showed that SEC-as a single dose or 3-day course-had comparable efficacy to multi-dose metronidazole for treating trichomoniasis in women and men, was generally well tolerated by patients, and had a favorable pharmacokinetic profile. A single 2-g dose of SEC also led to a microbiologic cure rate of 92.2% in the first randomized, double-blind, placebo-controlled study of trichomonas-infected US-based women.

CONCLUSION

SEC is an efficacious and safe treatment for women and men with trichomoniasis. Single-dose administration makes it a favorable treatment option for patients, especially in cases where adherence to other multi-dose treatment regimens could be problematic. Christina A. Muzny and Olivia T. Van Gerwen. Secnidazole for Trichomoniasis in Women and Men. Sex Med Rev 2022;10:255-262.

Synergistic effects of carvacrol, α-terpinene, γ-terpinene, ρ-cymene and linalool against Gardnerella species

Bacterial vaginosis (BV) is the most common vaginal infection affecting women worldwide. This infection is characterized by the loss of the dominant Lactobacillus community in the vaginal microbiota and an increase of anaerobic bacteria, that leads to the formation of a polymicrobial biofilm, mostly composed of Gardnerella spp. Treatment of BV is normally performed using broad-spectrum antibiotics, such as metronidazole and clindamycin. However, the high levels of recurrence of infection after treatment cessation have led to a demand for new therapeutic alternatives. Thymbra capitata essential oils (EOs) are known to have a wide spectrum of biological properties, including antibacterial activity. Thus, herein, we characterized two EOs of T. capitata and tested their antimicrobial activity as well as some of their main components, aiming to assess possible synergistic effects. Our findings showed that carvacrol and ρ-cymene established a strong synergistic antimicrobial effect against planktonic cultures of Gardnerella spp. On biofilm, carvacrol and linalool at sub-MIC concentrations proved more efficient in eliminating biofilm cells, while showing no cytotoxicity observed in a reconstituted human vaginal epithelium. The antibiofilm potential of the EOs and compounds was highlighted by the fact cells were not able to recover culturability after exposure to fresh medium.

Bridging the gap between development of point-of-care nucleic acid testing and patient care for sexually transmitted infections

The incidence rates of sexually transmitted infections (STIs), including the four major curable STIs - chlamydia, gonorrhea, trichomoniasis and, syphilis - continue to increase globally, causing medical cost burden and morbidity especially in low and middle-income countries (LMIC). There have seen significant advances in diagnostic testing, but commercial antigen-based point-of-care tests (POCTs) are often insufficiently sensitive and specific, while near-point-of-care (POC) instruments that can perform sensitive and specific nucleic acid amplification tests (NAATs) are technically complex and expensive, especially for LMIC. Thus, there remains a critical need for NAAT-based STI POCTs that can improve diagnosis and curb the ongoing epidemic. Unfortunately, the development of such POCTs has been challenging due to the gap between researchers developing new technologies and healthcare providers using these technologies. This review aims to bridge this gap. We first present a short introduction of the four major STIs, followed by a discussion on the current landscape of commercial near-POC instruments for the detection of these STIs. We present relevant research toward addressing the gaps in developing NAAT-based STI POCT technologies and supplement this discussion with technologies for HIV and other infectious diseases, which may be adapted for STIs. Additionally, as case studies, we highlight the developmental trajectory of two different POCT technologies, including one approved by the United States Food and Drug Administration (FDA). Finally, we offer our perspectives on future development of NAAT-based STI POCT technologies.

Recent insights suggest the need for the STI field to embrace a more eco-social conceptual framework: A viewpoint

A large number of countries are being confronted with twin epidemics of increasing STI incidence and antimicrobial resistance (AMR). This has led to calls to intensify STI screening of high STI prevalence populations. The available evidence suggests that this will have little impact on STI prevalence but a significant deleterious effect on AMR. We suggest that this call to intensify STI screening is one of the several errors that stem from the way that the STI-field has been dominated by a biomedical individualistic conceptual framework. This framework views STIs as obligate pathogens that can and should be eradicated by intensive seek-and-destroy activities. We evaluate five types of evidence that suggest that a multi-level, socio-ecological framework would provide a more accurate portrayal of the important determinants of STI prevalence and AMR spread. By incorporating concepts such as limiting STI screening to scenarios with clear evidence of net-benefit and considering 'antimicrobial footprint' thresholds, this framework would be more likely to result in a better balance between targeting STI prevalence whilst minimizing the risk of AMR emerging.

Lactic acid gel versus metronidazole for recurrent bacterial vaginosis in women aged 16 years and over: the VITA RCT

Background

Bacterial vaginosis is a common and distressing condition associated with serious comorbidities. Antibiotic treatment is usually clinically effective in the short term, but recurrence is common and side effects can occur.

Objectives

The objective is to assess whether or not intravaginal lactic acid gel is clinically effective and cost-effective for treating recurrent bacterial vaginosis compared with oral metronidazole (Flagyl, Sanofi).

Design

This was an open-label, multicentre, parallel-arm, randomised (1 : 1) controlled trial.

Setting

This took place in one general practice and 19 sexual health centres in the UK.

Participants

Women aged ≥ 16 years with bacterial vaginosis symptoms and one or more episode(s) within the past 2 years took part.

Interventions

The interventions were 5 ml of intravaginal lactic acid gel taken once daily for 7 days (intervention) or 400-mg oral metronidazole tablets taken twice daily for 7 days (control).

Main outcome measures

The primary outcome was the resolution of bacterial vaginosis symptoms 14 days after randomisation. The secondary outcomes were time to first recurrence of symptoms; number of recurrences and treatment courses over 6 months; microbiological resolution on microscopy of vaginal smears at week 2; time to resolution of symptoms; tolerability, adherence and acceptability of the treatment; prevalence of concurrent sexually transmitted infections; quality of life; and cost-effectiveness.

Results

Recruitment stopped prior to reaching the target of 1900 participants on recommendation from the Data Monitoring Committee and Trial Steering Committee after a planned review of the results indicated that the research question had been answered. Overall, 518 participants were randomised and primary outcome data were available for 409 participants (79%; 204 in the metronidazole arm, 205 in the lactic acid gel arm). Participant-reported symptom resolution at week 2 was higher with metronidazole (143/204; 70%) than with lactic acid gel (97/205; 47%) (adjusted risk difference –23.2%, 95% confidence interval –32.3% to –14.0%). Recurrence in 6 months in a subset of participants who had initial resolution and were available for follow-up was similar across arms (metronidazole arm: 51/72, 71%; lactic acid gel arm: 32/46, 70%). A higher incidence of some side effects was reported with metronidazole than with lactic acid gel (nausea 32% vs. 8%; taste changes 18% vs. 1%; diarrhoea 20% vs. 6%, respectively). At week 2, the average cost per participant with resolved symptoms was £86.94 (metronidazole), compared with £147.00 (lactic acid gel). Some participants preferred using lactic acid gel even if they perceived it to be less effective than metronidazole.

Limitations

Loss to follow-up for collection of the primary outcome data was 21% and was similar in both arms. There is a risk of bias owing to missing outcome data at 3 and 6 months post treatment.

Conclusions

A higher initial response was seen with metronidazole than with lactic acid gel, but subsequent treatment failure was common with both. Lactic acid gel was less cost-effective than metronidazole. In general, women disliked taking repeated courses of metronidazole and preferred lactic acid gel, even when they were aware that it was less likely to provide symptom resolution. In the absence of effective curative therapy, further evaluation of non-antibiotic treatments to control the symptoms of recurrent bacterial vaginosis is required to improve quality of life for these patients. Further microbiological analysis of vaginal samples would be useful to identify additional factors affecting response to treatment.

Trial registration

Current Controlled Trials ISRCTN14161293.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 2. See the NIHR Journals Library website for further project information.

Bacterial vaginosis and health-associated bacteria modulate the immunometabolic landscape in 3D model of human cervix

Bacterial vaginosis (BV) is an enigmatic polymicrobial condition characterized by a depletion of health-associated Lactobacillus and an overgrowth of anaerobes. Importantly, BV is linked to adverse gynecologic and obstetric outcomes: an increased risk of sexually transmitted infections, preterm birth, and cancer. We hypothesized that members of the cervicovaginal microbiota distinctly contribute to immunometabolic changes in the human cervix, leading to these sequelae. Our 3D epithelial cell model that recapitulates the human cervical epithelium was infected with clinical isolates of cervicovaginal bacteria, alone or as a polymicrobial community. We used Lactobacillus crispatus as a representative health-associated commensal and four common BV-associated species: Gardnerella vaginalis, Prevotella bivia, Atopobium vaginae, and Sneathia amnii. The immunometabolic profiles of these microenvironments were analyzed using multiplex immunoassays and untargeted global metabolomics. A. vaginae and S. amnii exhibited the highest proinflammatory potential through induction of cytokines, iNOS, and oxidative stress-associated compounds. G. vaginalis, P. bivia, and S. amnii distinctly altered physicochemical barrier-related proteins and metabolites (mucins, sialic acid, polyamines), whereas L. crispatus produced an antimicrobial compound, phenyllactic acid. Alterations to the immunometabolic landscape correlate with symptoms and hallmarks of BV and connected BV with adverse women’s health outcomes. Overall, this study demonstrated that 3D cervical epithelial cell colonized with cervicovaginal microbiota faithfully reproduce the immunometabolic microenvironment previously observed in clinical studies and can successfully be used as a robust tool to evaluate host responses to commensal and pathogenic bacteria in the female reproductive tract.

Efficacy and Safety of Single Oral Dosing of Secnidazole for Trichomoniasis in Women: Results of a Phase 3, Randomized, Double-Blind, Placebo-Controlled, Delayed-Treatment Study

Background

Trichomonas vaginalis is the most prevalent nonviral sexually transmitted infection. We evaluated the efficacy and safety of secnidazole vs placebo in women with trichomoniasis.

Methods

Women with trichomoniasis, confirmed by a positive T. vaginalis culture, were randomized to single-dose oral secnidazole 2 g or placebo. The primary endpoint was microbiological test of cure (TOC) by culture 6–12 days after dosing. At the TOC visit, participants were given the opposite treatment. They were followed for resolution of infection afterward and offered treatment at subsequent visits, if needed. Fifty patients per group (N = 100) provided approximately 95% power to detect a statistically significant difference between treatment groups.

Results

Between April 2019 and March 2020, 147 women enrolled at 10 sites in the United States. The modified intention-to-treat (mITT) population included 131 randomized patients (secnidazole, n = 64; placebo, n = 67). Cure rates were significantly higher in the secnidazole vs placebo group for the mITT population (92.2% [95% confidence interval {CI}: 82.7%–97.4%] vs 1.5% [95% CI: .0%–8.0%]) and for the per-protocol population (94.9% [95% CI: 85.9%–98.9%] vs 1.7% [95% CI: .0%–8.9%]). Cure rates were 100% (4/4) in women with human immunodeficiency virus (HIV) and 95.2% (20/21) in women with bacterial vaginosis (BV). Secnidazole was generally well tolerated. The most frequently reported treatment-emergent adverse events (TEAEs) were vulvovaginal candidiasis and nausea (each 2.7%). No serious TEAEs were observed.

Conclusions

A single oral 2 g dose of secnidazole was associated with significantly higher microbiological cure rates vs placebo, supporting a role for secnidazole in treating women with trichomoniasis, including those with HIV and/or BV.

Clinical Trials Registration

NCT03935217.

In silico trio-biomarkers for bacterial vaginosis revealed by species dominance network analysis

BV (bacterial vaginosis) influences 20%–40% of women but its etiology is still poorly understood. An open question about the BV is which of the hundreds of bacteria found in the human vaginal microbiome (HVM) are the major force driving the vaginal microbiota dysbiosis. Here, we recast the question of microbial causality of BV by asking if there are any prevalent ‘signatures’ (network motifs) in the vaginal microbiome networks associated with it? We apply a new framework [species dominance network analysis by Ma & Ellison (2019): Ecological Monographs) to detect critical structures in HVM networks associated with BV risks and etiology. We reanalyzed the 16 s-rRNA gene sequencing datasets of a mixed-cohort of 25 BV patients and healthy women. In these datasets, we detected 15 trio-motifs that occurred exclusively in BV patients. We failed to find any of these 15 trio-motifs in three additional cohorts of 1535 healthy women. Most member-species of the 15 trio motifs are BV-associated anaerobic bacteria (BVAB), Ravel’s community-state type indicators, or the most dominant species; virtually all species interactions in these trios are high-salience skeletons, suggesting that those trios are strongly connected ‘cults’ associated with the occurrence of BV. The presence of the trio motifs unique to BV may act as indicators for its personalized diagnosis and could help elucidate a more mechanistic interpretation of its risks and etiology. We caution that scarcity of large longitudinal datasets of HVM also limited further verifications of our findings, and these findings require further clinical tests to launch their applications.

Bacterial vaginosis and its association with infertility, endometritis, and pelvic inflammatory disease

Bacterial vaginosis, pelvic inflammatory disease, and endometritis are infections of the genital tract that can lead to many adverse health outcomes, including infertility. Bacterial vaginosis is characterized by a lower prevalence of lactobacilli and a higher prevalence of anaerobic bacteria, including Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae. Endometritis and pelvic inflammatory disease are caused by the ascension of pathogenic bacteria to the uterus, although the mechanisms by which they do so are unclear. Bacterial vaginosis, chronic endometritis, and pelvic inflammatory disease have been linked to infertility in retrospective and prospective trials. Similarly, the causes of bacterial vaginosis and endometritis-related infertility are likely multifactorial and stem from inflammation, immune targeting of sperm antigens, the presence of bacterial toxins, and increased risk of sexually transmitted infections. Diagnosis and treatment of bacterial vaginosis, chronic endometritis, and pelvic inflammatory disease before attempting conception may be important components of preconceptional care for symptomatic women to improve outcomes of natural and assisted reproduction.