The biofilm in bacterial vaginosis: implications for epidemiology, diagnosis and treatment: 2018 update

The microbial revolution: Unveiling the benefits of vaginal probiotics and prebiotics

Vaginal health is essential to a woman's overall well-being, as abnormalities in vaginal health can lead to a variety of gynaecological disorders, such as urinary tract infections, yeast infections, and bacterial vaginosis. The vaginal microbiome is essential for the prevention of these infections. Disruptions in this microbial ecosystem can significantly impact vaginal health. The concept of utilizing probiotics and prebiotics to stimulate the growth of protective vaginal microbiota has gathered substantial interest in recent years. Probiotics are live micro-organisms that strengthen and restore vaginal microbial balance by lowering pH levels, production of bacteriocins, biofilm disruption, modulation of immune response, and production of hydrogen peroxide (H2O2), consequently combating the development of pathogens. Prebiotics are oligosaccharides that encourage the development of probiotics such as lactobacilli species. Probiotics and prebiotics also have some broader implications for vaginal health, including their role in minimizing the incidence of premature birth, optimizing fertility, managing menopausal symptoms, and preventing vaginal infections. Synbiotics are a combination of probiotics and prebiotics that deliver additional benefits by encouraging the development and activity of beneficial microbes. Furthermore, postbiotics are bioactive compounds derived from probiotic bacteria during fermentation that have immunomodulatory actions and provide an additional layer of protection against vaginal infections. The present study highlights the most prevalent vaginal infections and limitations of existing therapies that influence the vaginal microbiota. The profound consequences of probiotics and prebiotics in women's health, including their role in minimizing the prevalence of vaginal infections and promoting overall vaginal health, as well as advanced therapeutic strategies such as synbiotics and postbiotics, are also discussed. The literature offers significant insights into the mechanism, efficacy, and safety of probiotics and prebiotics to healthcare providers and researchers.

POLARIS: efficacy and safety of a vaginal medical device in recurrent bacterial vaginosis-a multicenter, open-label, non-controlled, study with 10 months of follow-up

OBJECTIVE

Recurrent bacterial vaginosis (RBV) after antibiotic treatment has relapse rates of 35% within 3 months and 60% within 12 months. A medical device containing polycarbophil, lauryl glucoside, and glycerides (PLGG) inhibits bacterial growth and has mucoadhesive properties. This study examined the efficacy of the device in women with RBV.

METHODS

This post-market clinical follow-up study comprised two phases. The first phase was an interventional, open-label, non-controlled, multicenter study enrolling 56 women. The second phase was an observational 10-month follow-up without treatment.

RESULTS

After three cycles of PLGG treatment, recurrence was identified in 8 of 54 evaluable patients (14.81%). A positive effect on lactobacilli in the vaginal secretions was observed in 26 of 39 patients (66.67%). Among 35 patients observed after stopping PLGG treatment, one case of RBV (2.86%) was observed after 4 months, and an additional six cases (17.14%) were observed after 10 ± 2 months. Therefore, no recurrence was evidenced in 12 subjects (34.28%) at the end of the study.

CONCLUSION

The use of PLGG vaginal ovules in the treatment of BV reduces the rate of recurrence and apparently produces a positive effect on the vaginal microbiota.

Antibiofilm Agents for the Treatment and Prevention of Bacterial Vaginosis: A Systematic Narrative Review

BACKGROUND

Bacterial vaginosis (BV) is difficult to eradicate due to BV biofilms protecting BV bacteria (Gardnerella, Prevotella, and other genera). With the growing understanding of biofilms, we systematically reviewed the current knowledge on the efficacy of anti-BV biofilm agents.

METHODS

We searched literature in the Scopus, Medline, and Embase databases for empirical studies investigating substances for the treatment of BV biofilms or prevention of their recurrence and their efficacy and/or safety.

RESULTS

Of 201 unique titles, 35 satisfied the inclusion criteria. Most studies (89%) reported on preclinical laboratory research on the efficacy of experimental antibiofilm agents (80%) rather than their safety. Over 50% were published within the past 5 years. Agents were classified into 7 groups: antibiotics, antiseptics, cationic peptides, enzymes, plant extracts, probiotics, and surfactants/surfactant components. Enzymes and probiotics were most commonly investigated. Earlier reports of antibiotics having anti-BV biofilm activity have not been confirmed. Some compounds from other classes demonstrated promising anti-BV biofilm efficacy in early studies.

CONCLUSIONS

Further research is anticipated on successful antibiofilm agents. If confirmed as effective and safe in human clinical trials, they may offer a breakthrough in BV treatment. With rising antibiotic resistance, antibiofilm agents will significantly improve the current standard of care for BV management.

Different Forms of TFF3 in the Human Endocervix, including a Complex with IgG Fc Binding Protein (FCGBP), and Further Aspects of the Cervico-Vaginal Innate Immune Barrier

TFF3 is a typical secretory poplypeptide of mucous epithelia belonging to the trefoil factor family (TFF) of lectins. In the intestine, respiratory tract, and saliva, TFF3 mainly exists as a high-molecular-mass complex with IgG Fc binding protein (FCGBP), which is indicative of a role in mucosal innate immunity. For the first time, we identified different forms of TFF3 in the endocervix, i.e., monomeric and homodimeric TFF3, as well as a high-molecular-mass TFF3-FCGBP complex; the latter also exists in a hardly soluble form. Immunohistochemistry co-localized TFF3 and FCGBP. Expression analyses of endocervical and post-menopausal vaginal specimens revealed a lack of mucin and TFF3 transcripts in the vaginal specimens. In contrast, genes encoding other typical components of the innate immune defense were expressed in both the endocervix and vagina. Of note, FCGBP is possibly fucosylated. Endocervical specimens from transgender individuals after hormonal therapy showed diminished expression, particularly of FCGBP. Furthermore, mucus swabs from the endocervix and vagina were analyzed concerning TFF3, FCGBP, and lysozyme. It was the aim of this study to illuminate several aspects of the cervico-vaginal innate immune barrier, which is clinically relevant as bacterial and viral infections are also linked to infertility, pre-term birth and cervical cancer.

Cervicovaginal Gardnerella sialidase-encoding gene in persistent human papillomavirus infection

Disturbed vaginal microbiota have a role in the persistence of high-oncogenic-risk human papillomavirus (hrHPV) and Gardnerella spp. is closely related with this condition. Such bacteria are the major source of cervicovaginal sialidases, important for microbiota alterations. The sialidase-encoding gene nanH3 is account for their sialidase activity. Thus, a subset of 212 women positive for hrHPV at the first visit were included in the analysis of the current study aiming to compare the loads of nanH3 in cervicovaginal fluid (CFV) of women with persistent hrHPV infection and with those cleared the infection after a year. Participants were assigned to two study groups named "persistence" (n = 124, 53.22%) or "clearance" (n = 88, 37.77%), according to the HPV status upon enrollment and follow-up. Absolute quantification of nanH3 gene was performed using quantitative real-time PCR (qPCR). Persistence and clearance group did not show statistical difference in the load of nanH3 gene (p = 0.19). When considering the subset of women with HPV16, differences in number of copies of nanh3 gene was observed between the persistent (7.39E+08 copies/μL) and clearance group (2.85E+07 copies/μL) (p = 0.007). Therefore, baseline loads of nanH3 gene is increased in women that persist with cervical HPV16 infection after 12 months.

Biofilm-Forming Capacity and Drug Resistance of Different Gardnerella Subgroups Associated with Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common infection of the lower reproductive tract among women of reproductive age. Recurrent infections and antibiotic resistance associated with biofilms remain significant challenges for BV treatment. Gardnerella species are commonly found in women with and without BV, indicating that genetic differences among Gardnerella isolates may distinguish pathogenic from commensal subgroups. This study isolated 11 Gardnerella strains from vaginal samples obtained from women with BV before or after treatment. The biofilm formation ability of each strain was examined by crystal violet staining. Eight strains were selected using phylogenetic analysis of the cpn60 sequences and classified as subgroups A (6/8), B (1/8), and D (1/8). The biofilm formation ability and antibiotic resistance profile of these strains was compared among the subgroups. Subgroup D had the strongest biofilm formation ability. Six of the planktonic strains exhibited resistance to the first-line BV drug, metronidazole, and one to clindamycin. Moreover, biofilm formation in vitro increased strain resistance to clindamycin. Two strains with strong biofilm ability, S20 and S23, and two with weak biofilm ability, S24 and S25, were selected for comparative genomic analysis. S20 and S23 were found to contain four key genes associated with biofilm formation and more genes involved in carbohydrate synthesis and metabolism than S24 and S25. Identifying differences in the expression of virulence factors between Gardnerella subgroups could inform the development of novel treatments for BV.

Performance and Safety of a New Medical Device (Polybactum) for Reducing the Recurrence Rate of Bacterial Vaginosis: Protocol for a Multicenter, Open-Label, Noncontrolled International Clinical Trial (POLARIS Study)

BACKGROUND

The medical literature has reported that recurrent bacterial vaginosis (RBV) has a relapse rate of 35% within 3 months and 60% within 12 months after antibiotic administration. Products that are able to provide a barrier effect against the biofilm produced by Gardnerella vaginalis could play a role in improving the results of bacterial vaginosis (BV) treatment.

OBJECTIVE

This study aims to assess the performance and safety of a medical device (Polybactum) containing polycarbophil, lauryl glucoside, and glycerides (PLGG) for reducing the rate of recurrence of BV.

METHODS

The study includes women who are aged above 18 years, are willing to provide signed informed consent, have a diagnosis of BV according to the Amsel criteria, and have been affected by at least 2 episodes of RBV in the last 12 months. The trial includes 2 phases. In the first phase (according to an open-label noncontrolled design), the treatment involving PLGG is administered for 3 cycles and is followed by a 1-month period of follow-up without treatment. In the second phase, a 9-month follow-up period is envisaged. Thus, for each patient, a 10-month follow-up period without treatment is planned. The study involves 5 centers (2 in Italy and 3 in Romania). We calculated a sample size of 44 pairs to achieve a power of 80% and a 1-sided significance of 5% for detecting a difference of 0.25 between marginal proportions, in comparison with the mean recurrence rate of BV reported in the medical literature. We estimated a potential dropout rate of 20%, and thus, we decided to enroll 55 patients (1-group chi-square test).

RESULTS

The study received ethics approval in 2016 in Romania and 1 year later in Italy. Recruitment started in September 2016. An interim analysis was performed in 2019, and full study analysis results are expected in July 2023.

CONCLUSIONS

The tested medical device involving PLGG could modify the mechanisms involved in the pathogenesis of BV and could improve microbiological parameters owing to the acidifying effect on vaginal pH. We believe that the findings of our study could be useful for other investigators who want to test different products against RBV using a standardized protocol and standardized procedures.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02863536; https://clinicaltrials.gov/ct2/show/NCT02863536.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/42787.

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 18^th September 2017.

Microbiome and Vulvovaginitis

Vulvovaginitis occurs in mostly reproductive aged women. Recurrent vaginitis affects overall quality of life, with a large financial burden on the patient, family, and health system. This review discusses a clinician's approach to vulvovaginitis with specific attention to the 2021 updated Center for Disease Control and Prevention guidelines. The authors discuss the role of the microbiome in vaginitis and evidence-based approaches for diagnosis and treatment of vaginitis. This review also provides updates on new considerations, diagnosis, management, and treatment of vaginitis. Desquamative inflammatory vaginitis and genitourinary syndrome of menopause are discussed as differential diagnosis of vaginitis symptoms.

Distinct cervical tissue-adherent and luminal microbiome communities correlate with mucosal host gene expression and protein levels in Kenyan sex workers

BACKGROUND

The majority of studies characterizing female genital tract microbiota have focused on luminal organisms, while the presence and impact of tissue-adherent ectocervical microbiota remain incompletely understood. Studies of luminal and tissue-associated bacteria in the gastrointestinal tract suggest that these communities may have distinct roles in health and disease. Here, we performed a multi-omics characterization of paired luminal and tissue samples collected from a cohort of Kenyan female sex workers.

RESULTS

We identified a tissue-adherent bacterial microbiome, with a higher alpha diversity than the luminal microbiome, in which dominant genera overall included Gardnerella and Lactobacillus, followed by Prevotella, Atopobium, and Sneathia. About half of the L. iners-dominated luminal samples had a corresponding Gardnerella-dominated tissue microbiome. Broadly, the tissue-adherent microbiome was associated with fewer differentially expressed host genes than the luminal microbiome. Gene set enrichment analysis revealed that L. crispatus-dominated tissue-adherent communities were associated with protein translation and antimicrobial activity, whereas a highly diverse microbial community was associated with epithelial remodeling and pro-inflammatory pathways. Tissue-adherent communities dominated by L. iners and Gardnerella were associated with lower host transcriptional activity. Tissue-adherent microbiomes dominated by Lactobacillus and Gardnerella correlated with host protein profiles associated with epithelial barrier stability, although with a more pro-inflammatory profile for the Gardnerella-dominated microbiome group. Tissue samples with a highly diverse composition had a protein profile representing cell proliferation and pro-inflammatory activity.

CONCLUSION

We identified ectocervical tissue-adherent bacterial communities in all study participants of a female sex worker cohort. These communities were distinct from cervicovaginal luminal microbiota in a significant proportion of individuals. We further revealed that bacterial communities at both sites correlated with distinct host gene expression and protein levels. The tissue-adherent bacterial community could possibly act as a reservoir that seed the lumen with less optimal, non-Lactobacillus, bacteria. Video Abstract.

A review on biofilms and the currently available antibiofilm approaches: Matrix-destabilizing hydrolases and anti-bacterial peptides as promising candidates for the food industries

Biofilms are communities of microorganisms that can be harmful and/or beneficial, depending on location and cell content. Since in most cases (such as the formation of biofilms in laboratory/medicinal equipment, water pipes, high humidity-placed structures, and the food packaging machinery) these bacterial and fungal communities are troublesome, researchers in various fields are trying to find a promising strategy to destroy or slow down their formation. In general, anti-biofilm strategies are divided into the plant-based and non-plant categories, with the latter including nanoparticles, bacteriophages, enzymes, surfactants, active peptides and free fatty acids. In most cases, using a single strategy will not be sufficient to eliminate biofilm, and consequently, two or more strategies will inevitably be used to deal with this unwanted phenomenon. According to the analysis of potential biofilm inhibition strategies, the best option for the food industry would be the use of hydrolase enzymes and peptides extracted from natural sources. This article represents a systematic review of the previous efforts made in these directions.

Antimicrobial activity of bovine lactoferrin against Gardnerella species clinical isolates

Gardnerella species play a key role in the development and recurrence of Bacterial Vaginosis (BV), a common imbalance of the vaginal microbiota. Because of the high rates of BV recurrence reported after treatment with standard of care antibiotics, as well as the emergence of antibiotic-resistant BV, the development of alternative treatment approaches is needed. Bovine lactoferrin, a well studied iron-binding glycoprotein with selective antimicrobial activity, may ameliorate vaginal dysbiosis either alone or in combination with antibiotics. The present study evaluated the antimicrobial resistance/susceptibility profile of seventy-one presumptive G. vaginalis clinical isolates to metronidazole and clindamycin. In addition, the in vitro antimicrobial activity of Metrodora Therapeutics bovine Lactoferrin (MTbLF) against the tested clinical isolates, both alone and in combination with metronidazole and clindamycin, was in depth evaluated using defined-iron culture conditions. All 71 presumptive G. vaginalis clinical isolates exhibited resistance to metronidazole, with MIC values greater than 256 μg/ml. Different susceptibility profiles were detected for clindamycin. In detail, the vast majority of the tested strains (45%), exhibiting MIC lower than 2 μg/ml, were considered sensitive; 18 strains (25%) with MIC higher or equal to 8 μg/ml, were classified as resistant, whereas the remaining 21 (30%) were classified as intermediate. MTbLF was tested in culture medium at different concentrations (32, 16, 8, 4, 2, 1, and 0.5 mg/ml) showing ability to inhibit the growth of the tested presumptive G. vaginalis clinical isolates, including those metronidazole-resistant, in a dose-dependent and not in a strain-dependent manner. MTbLF, at concentrations ranging from 32 to 8 mg/ml, exerted a statistically different antimicrobial activity compared with lower concentrations (4, 2, 1, and 0.5 mg/ml). A synergistic effect between MTbLF (8 and 4 mg/ml) and clindamycin was revealed for all the tested strains. When tested in the absence of other sources of iron, MTbLF did not support the growth of the tested presumptive G. vaginalis clinical isolates. Bovine lactoferrin may be a potential candidate to treat Gardnerella species infection.

Human Trial for the Effect of Plasma-Activated Water Spray on Vaginal Cleaning in Patients with Bacterial Vaginosis

Underwater plasma discharge temporally produces several reactive radicals and/or free chlorine molecules in water, which is responsible for antimicrobial activity. Hence, it can simply sanitize tap water without disinfectant treatment. Additionally, the spraying technique using cleaning water exploits deep application in the narrow and curved vaginal tract of patients. Herein, we attempted a clinical trial to evaluate the vaginal cleaning effect of spraying plasma-activated water (PAW) to patients with vaginitis (46 patients). The efficacy was compared with treatment with betadine antiseptics used to treat bacterial vaginosis (40 patients). To evaluate the cleaning effect, Gram staining of the vaginal secretions was conducted before and after spraying PAW or betadine treatment (BT). Consequently, PAW-sprayed (PAWS) patients (22.3%) showed a better vaginal cleaning effect against Gram-positive and -negative bacteria than BT patients (14.4%). Moreover, 18 patients in the BT group showed worsened vaginal contamination, whereas five patients in the PAWS group showed worsened vaginal contamination. Taken together, the noncontact method of spraying cleaning water to the vagina exhibited a reliable vaginal cleaning effect without further bacterial infection compared with BT. Therefore, we suggest a clinical application of the spraying method using PAW for vaginal cleaning to patients with vaginitis without disinfectants and antibiotics.

Cervicovaginal loads of Gardnerella spp. are increased in immunocompetent women with persistent high-risk human papillomavirus infection

Introduction. Two high-oncogenic-risk human papilomavirus (hrHPV) genotypes - HPV16 and HPV18 - cause most of the cases of cervical cancer worldwide. Bacterial vaginosis is associated with increased hrHPV persistence, although the mechanism underlying this association remains unclear. Gardnerella spp. are detected in nearly all cases of bacterial vaginosis and are the major source of cervicovaginal sialidases. The NanH1 gene is present in virtually all Gardnerella sialidase-producing strains and has been proposed as a potential marker for persistent hrHPV infection.Hypothesis. Gardnerella spp. load and the NanH1 gene are associated with hrHPV persistence.Aim. To compare the cervicovaginal load of Gardnerella spp. and the frequency of the NanH1 gene between women with persistent HPV16 and/or HPV18 infection and those who cleared the infection after 11 months.Methodology. Among a population of 1638 HPV screened, we detected 104 with positive HPV16 and/or HPV18 results. Samples were obtained at two time points (baseline and at a median of 11 months at follow-up) and tested using the Linear Array HPV Genotyping kit (Roche Molecular Systems, Pleasanton, CA, USA). Based on their HPV16/HPV18 status at enrolment and follow-up, participants were assigned to 'persistence' or 'clearance' groups. We used cervicovaginal fluid samples obtained upon enrolment to determine the load of the 23 s rRNA gene of Gardnerella spp. and the presence of the NanH1 gene using real-time polymerase chain reaction (PCR). We compared Gardnerella spp. loads and NanH1 frequency between the groups by, respectively, Mann-Whitney and chi-squared tests, with a P-value <0.05 considered to be significant.Results. Of the 104 participants who were positive for HPV16/HPV18, 73 (70.2 %) persisted with at least 1 of the baseline genotypes at follow-up, while 31 (29.8 %) cleared the infection in this time frame. Participants in the persistence group had significantly higher loads of Gardnerella spp. [5.8E+02 (0-3.0E+05) copies µl^-1] than those in the clearance group [9.9E+01 (0-7.7E+04) copies µl^-1] (P=0.03). The baseline frequency of NanH1 was higher in the persistence' (n=46, 63.0 %) than in the clearance (n=14, 45.2 %) group, although this was not statistically significant (P=0.09).Conclusion. These findings reinforce the negative effect of vaginal microbiota for the clearance of hrHPV and indicate a possible association between sialidase-producing species with hrHPV persistence.

Research Progress on the Correlation Between Gardnerella Typing and Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common infectious disease of the reproductive tract in women of childbearing age. It often manifests as an imbalance in the vaginal microbiome, including a decrease in Lactobacillus and an increase in anaerobic bacteria. While Gardnerella spp. are considered a major cause of BV, they are also detected in the vaginal microbiome of healthy women. G. vaginalis was the only recognized species of Gardnerella until a recent study characterized three new species, G. leopoldii, G. piotii, and G. swidsinskii. This review describes the different types and genetic diversity of Gardnerella, as well as new findings on the correlation between different Gardnerella spp. and BV.

Mechanistic Insights into Immune Suppression and Evasion in Bacterial Vaginosis

The immunological response to bacterial vaginosis (BV) remains poorly understood and recurrent BV is still a major public health burden especially in the pregnant population. This article reviews the potential mechanisms by which BV-associated bacteria suppress and circumvent the host and microbial defence responses, and propagate their survival/dominance without overt inflammation. We discuss the composition of cervicovaginal mucosal barrier and the mechanism by which BV circumvents host defence: the degradation of the mucosal barrier and immunoglobulin A (IgA); the BV-associated organism Gardnerella vaginalis haemolysin (vaginolysin); diminished IgA response against vaginolysin; mucosal sialic acid degradation, foraging and depletion; inhibition of IL-8-induced neutrophilic infiltration; and metabolite-induced incapacitation of neutrophil and monocyte chemotaxis. We also highlight the tolerance/resistance to both host and antimicrobial molecules mounted by BV-associated biofilms. A plausible role of sialic acid-binding immunoglobulin-like lectins (SIGLECS) was also suggested. Sialidase, which is often produced by G. vaginalis, is central to the immunosuppression, relapse and recurrence observed in BV, although it is supported by other hydrolytic enzymes, vaginolysin and immunomodulatory metabolites.

Crystal Violet Staining Alone Is Not Adequate to Assess Synergism or Antagonism in Multi-Species Biofilms of Bacteria Associated With Bacterial Vaginosis

Bacterial Vaginosis (BV) involves the presence of a multi-species biofilm adhered to vaginal epithelial cells, but its in-depth study has been limited due to the complexity of the bacterial community, which makes the design of in vitro models challenging. Perhaps the most common experimental technique to quantify biofilms is the crystal violet (CV) staining method. Despite its widespread utilization, the CV method is not without flaws. While biofilm CV quantification within the same strain in different conditions is normally accepted, assessing multi-species biofilms formation by CV staining might provide significant bias. For BV research, determining possible synergism or antagonism between species is a fundamental step for assessing the roles of individual species in BV development. Herein, we provide our perspective on how CV fails to properly quantify an in vitro triple-species biofilm composed of Gardnerella vaginalis, Fannyhessea (Atopobium) vaginae, and Prevotella bivia, three common BV-associated bacteria thought to play key roles in incident BV pathogenesis. We compared the CV method with total colony forming units (CFU) and fluorescence microscopy cell count methods. Not surprisingly, when comparing single-species biofilms, the relationship between biofilm biomass, total number of cells, and total cultivable cells was very different between each tested method, and also varied with the time of incubation. Thus, despite its wide utilization for single-species biofilm quantification, the CV method should not be considered for accurate quantification of multi-species biofilms in BV pathogenesis research.

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.

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: Effects on reproduction and its therapeutics

Bacterial Vaginosis (BV) is the most common vaginal infection. A large amount of evidence shows that the anatomical scope of BV's pathogenic effect is far beyond the lower reproductive tract. BV is closely related to adverse reproductive outcomes, which may be due to the infection of the vaginal flora ascending to the upper genital tract. In addition, the incidence of BV is relatively high in infertile women. The vaginal microbiome also plays an important role in women's health and diseases. For most women, the normal vaginal microbiota is dominated by Lactobacillus, which can maintain a healthy vaginal environment by producing lactic acid, H₂O₂ and bacteriocin, etc. BV is characterized by the imbalanced vaginal flora. It changes the acidic environment that is normally dominated by Lactobacillus, and causes an overgrowth of anaerobic and facultative anaerobic bacteria such as Gardnerella vaginalis and Atopobium vaginae. Studies have shown that bacterial infections in the vagina can spread to upper genital tract and cause adverse fertility outcome. Therefore, early diagnosis and therapeutics of symptomatic BV is helpful to improve the outcome of poor fertility.

Five Percent Monolaurin Vaginal Gel for the Treatment of Bacterial Vaginosis: A Randomized Placebo-Controlled Trial

OBJECTIVE

The aim of the study was to test the hypothesis that 5% monolaurin vaginal gel, a naturally occurring monoglyceride shown to have antimicrobial effects on vaginal pathogens without affecting Lactobacillus species, cures bacterial vaginosis (BV).

MATERIALS AND METHODS

This was a multicenter, double-blinded, randomized controlled trial comparing 5% monolaurin vaginal gel to vehicle placebo (glycol-based) gel administered twice daily for 3 days. Nonpregnant, nonbreastfeeding women between ages 18 and 50 years were recruited and BV confirmed. Primary outcome was clinical cure assessed by resolution of all 4 Amsel criteria. Secondary outcomes included safety and tolerability assessed by solicited urogenital adverse events. Exploratory outcomes included colony counts for vaginal microbes associated with healthy vaginal flora (Lactobacillus species) and the dysbiosis often associated with BV (Gardnerella species and Mobiluncus species). A 2:1 test article to placebo randomization scheme was planned.

RESULTS

One hundred nine women participated with 73 randomized to the treatment arm and 36 to the placebo arm. There was no significant difference in clinical cure for BV (p = .42) with 17% of the monolaurin group and 25% of the placebo group achieving clinical cure. Lactobacilli species counts increased in the monolaurin group compared with placebo (1.0 × 10 vs -5.2 × 10). Two thirds of both groups reported solicited urogenital adverse events, but these were mild to moderate with no significant difference between groups (p = .24).

CONCLUSIONS

Monolaurin was no more clinically or microbiologically effective than placebo in curing BV. Future research should explore whether monolaurin may be used to increase Lactobacilli species.

A Clinicopathological Diagnostic and Therapeutic Approach to Cytolytic Vaginosis: An Extremely Rare Entity that may Mimic Vulvovaginal Candidiasis

Objectives:

Cytolytic vaginosis is a very rare entity that may be clinically misdiagnosed as vulvovaginal candidiasis. The aim of this study was to determine the incidence of cytolytic vaginosis in patients displaying symptoms similar to vulvovaginal candidiasis and to develop a clinicopathological diagnostic and therapeutic approach.

Materials and Methods:

In total, 3000 cervical smear samples were evaluated at our center between 2015 and 2018. Patients whose PAP smears demonstrated significant epithelial cytolysis, naked nuclei, excessive increase in lactobacilli population, absent or minimal neutrophils and no microorganisms were subjected to a symptom assessment questionnaire and had their vaginal pHs measured. They were classified into two groups according to their complaints, symptoms and vaginal pHs: Cytolytic vaginosis and Asymptomatic intravaginal lactobacillus overgrowth. A standardized NaHCO3 Sitz bath therapy was applied to the cytolytic vaginosis group.

Results:

Fifty-three of the patients (1.7%) were diagnosed as cytolytic vaginosis. After Sitz bath therapy, there was a statistically significant decrease in the cytolysis and lactobacillus scores of the patients. Vaginal discharge of 43 (81%) patients ceased completely while that of the remaining 10 (19%) patients decreased after the therapy. The improvement was statistically significant (P < 0.001). There was a complete resolution in 28 (96%) patients with severe; and in 21 (94%) patients with intermediate vaginal discomfort, after the therapy. Dyspareunia was resolved in 35 (97%) patients (P < 0.001).

Conclusion:

Cytolytic vaginosis is a rare entity that can be diagnosed with the help of cytopathology and has a therapy based on the modulation microbiota by decreasing the vaginal pH.

Clinical research on traditional Chinese medicine treatment for bacterial vaginosis

Bacterial vaginosis (BV) is a common disease among women of reproductive age, with a serious impact on their daily life and health. At present, the most common treatment for BV is to take antibiotics, which results in good short-term treatment effects, but poor long-term effects. Traditional Chinese medicine (TCM) has been used to treat BV for over a millennium, with little risk of triggering drug resistance and adverse effects. Based on syndrome differentiation, there are three oral TCM treatment strategies for BV, including invigorating spleen, clearing dampness and heat, and nourishing kidney. The oral TCM prescriptions, such as Yi Huang decoction, Longdan Xiegan decoction, Zhibai Dihaung decoction, and so on are commonly used. Topical TCM treatment is also popular in China. According to the research results of pharmacological effects of active TCM ingredients, the most potential mechanisms of TCM for BV treatment are immune-enhancement effects, antibacterial activity, and estrogen-liked effects. Nonetheless, the multi-constituent of herbs may result in possible disadvantages to BV treatment, and the pharmacological mechanisms of TCM need further study. Here, we provide an overview of TCM compounds and their preparations used for BV, based on the pathogenesis and the potential therapeutic mechanisms, therefore providing a reference for further studies.

Recurrent bacterial vaginosis

ABSTRACT

Bacterial vaginosis increases the risk of sexually transmitted infections, including HIV, and treatment is crucial to avoid complications. This article reviews the evidence-based options for treating bacterial vaginosis to improve patient outcomes.

Lactobacillus rhamnosus and Lactobacillus casei Affect Various Stages of Gardnerella Species Biofilm Formation

Bacterial vaginosis (BV) and its recurrence are most commonly associated with the formation of Gardnerella species biofilm. Probiotics are typically used to treat BV; however, the optimal period of Lactobacillus probiotic application in BV treatment remains uncertain. The present study aimed to explore the effects of Lactobacillus rhamnosus and Lactobacillus casei on various stages of biofilm formation in Gardnerella species. The biofilm-forming ability of seven strains, including one Gardnerella vaginalis ATCC 14018 and six clinically isolated Gardnerella species, was determined via gentian violet staining assay. Moreover, the sensitivity of the planktonic and biofilm forms toward metronidazole and clindamycin was assessed via microdilution broth method. L. rhamnosus Xbb-LR-1 and L. casei Xbb-LC-1 were added during various stages of biofilm formation in Gardnerella species and were cocultured for 24 h. The biofilm thickness of each sample was determined via confocal laser scanning microscopy (CLSM). The absolute quantities of Gardnerella species in each sample was obtained via real time polymerase chain reaction method, and the pH value was obtained using a pH indicator paper. Biofilm formation by Gardnerella species in a medium with distinct pH values was observed via gentian violet staining, CLSM, and scanning electron microscopy (SEM). The biofilm increased the resistance of Gardnerella species toward metronidazole and clindamycin. L. rhamnosus added at the initial biofilm formation stage in Gardnerella species exhibited highest inhibitory effect, with a percentage inhibition of 38.17% ± 1.35%. When the pH value of the culture medium was <4.5 or >6.5, ATCC 14018 could hardly form a biofilm; however, at pH ≥4.5 and ≤6.5, it was able to form a stronger biofilm. The amount of biofilm attained maximum value at optical density of 3.29 ± 0.28 (595 nm), pH 5.5, and at 36 h. Biofilm formation increases the resistance of Gardnerella species toward antibiotics. Maintaining an acidic vaginal environment with pH <4.5 and a vaginal microbiota dominated by Lactobacillus remarkably prevents the formation of Gardnerella species biofilm at the initial stage, which further has a significant impact on the treatment and prevention of biofilm-related infections.

Novel Selective Inhibition of Lactobacillus iners by Lactobacillus-Derived Bacteriocins

Lactobacillus iners is often associated with vaginal dysbiosis and bacterial vaginosis (BV), which are risk factors for adverse gynecological and obstetric outcomes. To discover natural inhibitors of L. iners, cell-free culture supernatants (CFSs) from 77 vaginal human Lactobacillus strains and 1 human intestinal strain were screened for inhibitory activity. Three active strains were identified, and Lactobacillus paragasseri K7 (K7), a human intestinal strain, produced the most potent L. iners-inhibitory activity. The active material was purified from the K7 CFS and yielded three active peptides, identified as components of two different class IIb, two-peptide bacteriocins, gassericin K7A (GasK7A) and gassericin K7B (GasK7B). The peptides corresponded to the GasK7A α peptide and the GasK7B α and β peptides. While all three peptides exhibited individual activity against L. iners, GasK7B α was the most potent, with an MIC of 23 ng/ml (4 nM). When combined in equal amounts, the GasK7B α and β peptides showed synergistic inhibition, with an MIC of 2 ng/ml (each peptide at 0.4 nM). Among the four major vaginal Lactobacillus species, the K7 bacteriocins selectively inhibited L. iners All 21 strains of L. iners tested (100%) were inhibited by the K7 bacteriocins, whereas <20% of the vaginal Lactobacillus crispatus, L. jensenii, and L. gasseri strains were inhibited. The combination of the BV treatment metronidazole and K7 bacteriocins completely killed both L. iners and Gardnerella vaginalis in a coculture experiment to mimic BV conditions. In contrast, this treatment did not inhibit L. crispatus cultures.IMPORTANCELactobacillus iners is a prevalent species of the vaginal microbiome, but unlike other major vaginal Lactobacillus species, it is not considered protective against BV and can coexist with BV-associated bacteria. L. iners is generally the first Lactobacillus species to emerge following the treatment of BV with metronidazole, and mounting evidence suggests that it may contribute to the onset and maintenance of vaginal dysbiosis. The discovery of highly potent bacteriocins that selectively kill L. iners while sparing protective vaginal lactobacilli may provide novel pharmacological tools to better understand the roles of this enigmatic bacterium in vaginal ecology and potentially lead to new and improved therapies for dysbiosis-related conditions such as BV.

Recurrent bacterial vaginosis

Bacterial vaginosis recurrence is common but can lead to frequent bothersome symptoms associated with infection. This article reviews evidence-based options for practicing providers to improve patient outcomes. Bacterial vaginosis increases the risk of acquiring sexually transmitted infections, including HIV. Adequate treatment is essential to help avoid adverse patient outcomes.

Anti-Biofilm Properties of Saccharomyces cerevisiae CNCM I-3856 and Lacticaseibacillus rhamnosus ATCC 53103 Probiotics against G. vaginalis

Bacterial vaginosis (BV) is characterized by the presence of a polymicrobial biofilm where Gardnerella vaginalis plays a key role. Previously, we demonstrated that Saccharomyces cerevisiae CNCM (French National Collection of Cultures of Microorganisms) I-3856 is helpful in resolving experimental simulated BV in mice. In this study, we analyzed its capacity to affect G. vaginalis biofilms and to potentiate the activity of standard antimicrobial agents. We also investigated the anti-biofilm activity of Lacticaseibacillus rhamnosus GG (ATCC 53103), a well-known strain for its intestinal healthy benefits. Biofilm biomass was assessed by crystal violet staining, and G. vaginalis viability was assessed by a colony forming unit (CFU) assay. Here, for the first time, we demonstrated that S. cerevisiae CNCM I-3856 as well as L. rhamnosus GG were able (i) to significantly inhibit G. vaginalis biofilm formation, (ii) to markedly reduce G. vaginalis viability among the biomass constituting the biofilm, (iii) to induce disaggregation of preformed biofilm, and (iv) to kill a consistent amount of bacterial cells in a G. vaginalis preformed biofilm. Furthermore, S. cerevisiae CNCM I-3856 strongly potentiates the metronidazole effect on G. vaginalis biofilm viability. These results suggest that S. cerevisiae CNCM I-3856 as well as L. rhamnosus GG could be potential novel therapeutic agents against bacterial vaginosis.

Bacterial Vaginosis: Current Diagnostic Avenues and Future Opportunities

A healthy female genital tract harbors a microbiome dominated by lactic acid and hydrogen peroxide producing bacteria, which provide protection against infections by maintaining a low pH. Changes in the bacterial compositions of the vaginal microbiome can lead to bacterial vaginosis (BV), which is often associated with vaginal inflammation. Bacterial vaginosis increases the risk of acquiring sexually transmitted infections (STIs) like human immunodeficiency virus (HIV) and affects women's reproductive health negatively. In pregnant women, BV can lead to chorioamnionitis and adverse pregnancy outcomes, including preterm premature rupture of the membranes and preterm birth. In order to manage BV effectively, good diagnostic procedures are required. Traditionally clinical and microscopic methods have been used to diagnose BV; however, these methods require skilled staff and time and suffer from reduced sensitivity and specificity. New diagnostics, including highly sensitive and specific point-of-care (POC) tests, treatment modalities and vaccines can be developed based on the identification of biomarkers from the growing pool of vaginal microbiome and vaginal metabolome data. In this review the current and future diagnostic avenues will be discussed.

Bacterial vaginosis: Standard treatments and alternative strategies

Bacterial vaginosis (BV) affects many women and has a high influence on their self-esteem, being associated with huge discomfort and changes in the routines, especially the sexual life. International guidelines recommend the administration of metronidazole, clindamycin or tinidazole orally or intravaginally as the standard treatment. However, the treatment with these antibiotics is associated with high levels of failure and recurrence rates. These may be associated with antibiotic resistance, the inability to eradicate the polymicrobial biofilms, and failure to reestablish acidic pH and the lactobacillus-dominated commensal flora. Therefore, it is emergent to study alternative strategies to replace or to be combined with standard therapies in order to prevent and treat BV more efficiently. Alternative strategies may include antimicrobial substances (other antimicrobials, antiseptics and natural compounds) or substances that aim to reestablish the physiologic vaginal environment (probiotics, prebiotics and acidifying agents) while improving the local immunity response. Besides, the development of formulation strategies and new dosage forms and drug delivery systems can improve treatment efficacy and overcome some limitations associated with conventional products.

Evaluation of the Inhibitory Effects of Lactobacillus gasseri and Lactobacillus crispatus on the Adhesion of Seven Common Lower Genital Tract Infection-Causing Pathogens to Vaginal Epithelial Cells

Background/Purpose: Lactobacillus colonization is important to maintain urogenital flora stability and prevent pathogenic infection. Different Lactobacillus species have distinct properties and effects on the urogenital flora. To select probiotics that colonize the vagina and provide protection against pathogenic infection, we evaluated the adhesion of five Lactobacillus strains and their inhibitory effects on the adhesion of pathogens to vaginal epithelial cells (VECs). Methods and Materials: (1) Lactobacillus adhesion experiments: VK2/E6E7 and primary VECs were used to evaluate the adhesion of two Lactobacillus gasseri and three Lactobacillus crispatus strains. The adhesion of these five Lactobacillus strains was compared. (2) Adhesion inhibition experiments: The inhibitory effects of the five Lactobacillus strains on the adhesion of pathogens (Gardnerella, Mobiluncus, Candida albicans, Streptococcus agalactiae, Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis) were evaluated by adhesion exclusion, displacement, and competition experiments. Results: (1) Lactobacillus adhesion was stronger in the primary VECs than in the VK2/E6E7 VECs (P < 0.05). The adhesion of the three L. crispatus strains was stronger than that of the two L. gasseri strains (P < 0.05). L. crispatus 4# showed the strongest adhesion. (2) The exclusion, displacement, and competition experiments showed that all five Lactobacillus strains significantly inhibited the adhesion of the seven pathogenic strains to the VECs (P < 0.05). The displacement effect was stronger than the exclusion and competition effects of each Lactobacillus strain. (3) The results of the exclusion, displacement, and competition experiments indicated that L. gasseri 1# showed the strongest adhesion inhibition of C. albicans and S. agalactiae. L. crispatus 3# showed the strongest adhesion inhibition of S. aureus, whereas L. crispatus 4# showed the strongest adhesion inhibition of Gardnerella, Mobiluncus, E. coli, and E. faecalis. Conclusion: The source of the VECs might not affect the selection of the most adhesive Lactobacillus strain. L. crispatus showed stronger VEC adhesion than L. gasseri. The degree of antagonism of the Lactobacillus strains toward the different pathogens varied. This result provides incentives for personalized clinical treatment.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

Cholesterol-Dependent Cytolysins Produced by Vaginal Bacteria: Certainties and Controversies

Bacterial vaginosis (BV) is a vaginal anaerobic dysbiosis that affects women of reproductive age worldwide. BV is microbiologically characterized by the depletion of vaginal lactobacilli and the overgrowth of anaerobic bacterial species. Accumulated evidence suggests that Gardnerella spp. have a pivotal role among BV-associated bacteria in the initiation and development of BV. However, Gardnerella spp. often colonize healthy women. Lactobacillus iners is considered as a prevalent constituent of healthy vaginal microbiota, and is abundant in BV. Gardnerella spp. and L. iners secrete the toxins vaginolysin (VLY) and inerolysin (INY), which have structural and activity features attributed to cholesterol-dependent cytolysins (CDCs). CDCs are produced by many pathogenic bacteria as virulence factors that participate in various stages of disease progression by forming lytic and non-lytic pores in cell membranes or via pore-independent pathways. VLY is expressed in the majority of Gardnerella spp. isolates; less is known about the prevalence of the gene that encodes INY. INY is a classical CDC; membrane cholesterol acts a receptor for INY. VLY uses human CD59 as its receptor, although cholesterol remains indispensable for VLY pore-forming activity. INY-induced damage of artificial membranes is directly dependent on cholesterol concentration in the bilayer, whereas VLY-induced damage occurs with high levels of membrane cholesterol (>40 mol%). VLY primarily forms membrane-embedded complete rings in the synthetic bilayer, whereas INY forms arciform structures with smaller pore sizes. VLY activity is high at elevated pH, which is characteristic of BV, whereas INY activity is high at more acidic pH, which is specific for a healthy vagina. Increased VLY levels in vaginal mucosa in vivo were associated with clinical indicators of BV. However, experimental evidence is lacking for the specific roles of VLY and INY in BV. The interplay between vaginal bacterial species affects the expression of the gene encoding VLY, thereby modulating the virulence of Gardnerella spp. This review discusses the current evidence for VLY and INY cytolysins, including their structures and activities, factors affecting their expression, and their potential impacts on the progression of anaerobic dysbiosis.

Diverse Expression of Antimicrobial Activities Against Bacterial Vaginosis and Urinary Tract Infection Pathogens by Cervicovaginal Microbiota Strains of Lactobacillus gasseri and Lactobacillus crispatus

We aimed to analyze the strain-by-strain expression of a large panel of antimicrobial activities counteracting the virulence mechanisms of bacterial vaginosis-associated Prevotella bivia CI-1 and Gardnerella vaginalis 594, pyelonephritis-associated Escherichia coli CFT073, and recurrent cystitis- and preterm labor-associated IH11128 E. coli by Lactobacillus gasseri and Lactobacillus crispatus clinical strains, and L. gasseri ATCC 9857 and KS 120.1, and L. crispatus CTV-05 strains isolated from the cervicovaginal microbiota of healthy women. All L. gasseri and L. crispatus strains exerted antimicrobial activity by secreted lactic acid, which killed the microbial pathogens by direct contact. Potent bactericidal activity was exerted by a very limited number of resident L. gasseri and L. crispatus strains showing the specific ability to a strain to produce and release antibiotic-like compounds. These compounds eradicated the microbial pathogens pre-associated with the surface of cervix epithelial cells, providing efficient protection of the cells against the deleterious effects triggered by toxin-producing G. vaginalis and uropathogenic E. coli. Furthermore, these compounds crossed the cell membrane to kill the pre-internalized microbial pathogens. In addition, all L. gasseri and L. crispatus cells exhibited another non-strain specific activity which inhibited the association of microbial pathogens with cervix epithelial cells with varying efficiency, partially protecting the cells against lysis and detachment triggered by toxin-producing G. vaginalis and uropathogenic E. coli. Our results provide evidence of strain-level specificity for certain antimicrobial properties among cervicovaginal L. gasseri and L. crispatus strains, indicating that the presence of a particular species in the vaginal microbiota is not sufficient to determine its benefit to the host. A full repertory of antimicrobial properties should be evaluated in choosing vaginal microbiota-associated Lactobacillus isolates for the development of live biotherapeutic strategies.

Modifications in Vaginal Microbiota and Their Influence on Drug Release: Challenges and Opportunities

Vaginal drug delivery represents an attractive alternative to achieve local and systemic effects due to the high contact surface exposed, the mucoadhesion of the epithelium, and the high innervation that facilitates the absorption of drugs into the bloodstream. However, despite the confinement of the vaginal cavity, it is an organ with a highly variable microenvironment. Mechanical alterations such as coitus, or chemical changes such as pH and viscosity, modify the release of drugs. In addition, changes in vaginal microbiota can influence the entire vaginal microenvironment, thus determining the disposition of drugs in the vaginal cavity and decreasing their therapeutic efficacy. Therefore, the influence of microorganisms on vaginal homeostasis can change the pre-established scenario for the application of drugs. This review aims to provide an explanation of normal vaginal microbiota, the factors that modify it, its involvement in the administration of drugs, and new proposals for the design of novel pharmaceutical dosage forms. Finally, challenges and opportunities directed toward the conception of new effective formulations are discussed.