Treatment of Male Sexual Partners of Women With Bacterial Vaginosis: A Randomized, Double-Blind, Placebo-Controlled Trial

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.

Vaginal Lactobacillus fatty acid response mechanisms reveal a novel strategy for bacterial vaginosis treatment

Bacterial vaginosis (BV), a common syndrome characterized by Lactobacillus-deficient vaginal microbiota, is associated with adverse health outcomes. BV often recurs after standard antibiotic therapy in part because antibiotics promote microbiota dominance by Lactobacillus iners instead of Lactobacillus crispatus, which has more beneficial health associations. Strategies to promote L. crispatus and inhibit L. iners are thus needed. We show that oleic acid (OA) and similar long-chain fatty acids simultaneously inhibit L. iners and enhance L. crispatus growth. These phenotypes require OA-inducible genes conserved in L. crispatus and related species, including an oleate hydratase (ohyA) and putative fatty acid efflux pump (farE). FarE mediates OA resistance, while OhyA is robustly active in the human vaginal microbiota and sequesters OA in a derivative form that only ohyA-harboring organisms can exploit. Finally, OA promotes L. crispatus dominance more effectively than antibiotics in an in vitro model of BV, suggesting a novel approach for treatment.

Relationship between Bacterial Vaginosis and Sexually Transmitted Infections: Coincidence, Consequence or Co-Transmission?

Sexually transmitted infections (STIs) are a serious global problem, causing disease, suffering, and death. Although bacterial vaginosis (BV) is not considered to be an STI, it may be associated with an increased risk of contracting a wide range of STIs. We sought to assess the link between the different microorganisms involved in STIs and BV. A total of 290 vaginal swabs from 290 women sent for diagnostic purposes to the clinical microbiology laboratory of the Marseille University Public Hospitals were tested by specific qPCR targeting STI-causing microorganisms and BV. Of these 290 swabs, 15.2% (44/290) were diagnosed with at least one STI-causing microorganism and 17.2% (50/290) with BV. The prevalence of STIs was significantly higher in women with BV (28%, 14/50) than in those without (20.4%, 51/240). The prevalence of co-infections involving two STI-causing microorganisms was significantly more frequent in women with BV than in those without (18% [8/50] vs. 2% [5/250]; p < 0.001). The prevalence of monoinfections and polyinfections with STI-causing microorganisms was lower in women without BV than in those with (8.8% [21/240] vs. 28% [14/50]), p < 0.001 and 2% (5/240) vs. 8% (4/50), p = 0.05, respectively). Our data suggest that a correlation between BV and STI may exist, with a higher prevalence of both monoinfections and polyinfections involving STI-causing microorganisms in women with BV. Further research is needed to better understand BV and its links to STIs.

Understanding and Preventing Recurring Bacterial Vaginosis: Important Considerations for Clinicians

Bacterial vaginosis (BV) is the most common vaginal infection worldwide. It is associated with an increased risk of acquisition of HIV and other sexually transmitted infections (STIs) as well as pelvic inflammatory disease and adverse birth outcomes. During BV, a polymicrobial biofilm forms on the surface of the vaginal mucosa. However, the exact etiology of BV remains controversial which has impeded significant advances in diagnosis, treatment, and prevention. Despite 30-day cure rates approaching 80% in BV-infected women treated with 7 days of oral metronidazole, recurrence within 12 months is common. This article provides a current review of the epidemiology, pathogenesis, diagnosis, and treatment of recurrent BV for practicing clinicians who commonly see women with this recurrent vaginal infection. Regarding management, we focus primarily on antimicrobial measures that may be effective. Future areas of research in this field are also discussed.

Sexual behavior shapes male genitourinary microbiome composition

The origin, composition, and significance of the distal male urethral microbiome are unclear, but vaginal microbiome dysbiosis is linked to new sex partners and several urogynecological syndromes. We characterized 110 urethral specimens from men without urethral symptoms, infections, or inflammation using shotgun metagenomics. Most urethral specimens contain characteristic lactic acid bacteria and Corynebacterium spp. In contrast, several bacteria associated with vaginal dysbiosis were present only in specimens from men who reported vaginal intercourse. Sexual behavior, but not other evaluated behavioral, demographic, or clinical variables, strongly associated with inter-specimen variance in urethral microbiome composition. Thus, the male urethra supports a simple core microbiome that is established independent of sexual exposures but can be re-shaped by vaginal sex. Overall, the results suggest that urogenital microbiology and sexual behavior are inexorably intertwined, and show that the male urethra harbors female urogenital pathobionts.

Approach to Managing Sex Partners of People with Sexually Transmitted Infections

Partner management of sexually transmitted infection (STIs) is essential to identify and treat new cases, prevent reinfection in the index case, interrupt chains of transmission, reduce STI-related morbidity, and target STI screening and treatment interventions. The responsibility for partner notification and treatment falls on the health care provider. Approaches to partner management include patient referral, provider referral, contractual referral, and expedited partner therapy (EPT), with EPT and enhanced partner referral outperforming other methods. This article provides an overview of clinical recommendations regarding partner management, with particular emphasis on EPT, and an update on new and emerging evidence in the field.

The Effects of Medical Male Circumcision on Female Partners' Sexual and Reproductive Health

PURPOSE OF REVIEW

Voluntary medical male circumcision (VMMC) reduces the risk of HIV acquisition by 60% among heterosexual men, provides protection against certain sexually transmitted infections (STI), and leads to penile microbiome composition changes associated with reduced risk of HIV infection. Intuitively, the benefits of VMMC for female sex partners in relation to STI are likely and have been evaluated. The purpose of this review is to examine emerging findings of broader sexual and reproductive health (SRH) benefits of VMMC for female sex partners.

RECENT FINDINGS

Systematic reviews find strong evidence for beneficial effects of VMMC on female sex partners risk of HPV, cervical dysplasia, cervical cancer, and with likely protection against trichomoniasis and certain genital ulcerative infections. Few studies assess the direct impact of VMMC on the vaginal microbiome (VMB), though several studies demonstrate reductions in BV, which is mediated by the VMB. Studies are lacking regarding male circumcision status and outcomes associated with non-optimal VMB, such as female infertility and adverse pregnancy outcomes. VMMC has positive effects on women's perceptions of sexual function and satisfaction, and perceptions of disease risk and hygiene, without evidence of risk compensation. VMMC has consistent association with a broad range of women's SRH outcomes, highlighting the biological and non-biological interdependencies within sexual relationships, and need for couples-level approaches to optimize SRH for men and women. The paucity of information on VMMC and influence on VMB is a barrier to optimizing VMB-associated SRH outcomes in female partners.

Diagnosis and Management of Bacterial Vaginosis: Summary of Evidence Reviewed for the 2021 Centers for Disease Control and Prevention Sexually Transmitted Infections Treatment Guidelines

In preparation for the 2021 Centers for Disease Control and Prevention (CDC) sexually transmitted infections (STIs) treatment guidelines, the CDC convened an advisory group in 2019 to examine recent literature addressing updates in the epidemiology, diagnosis, and management of STIs. This article summarizes recent data in each of these key topic areas as they pertain to bacterial vaginosis (BV), the most common cause of vaginal discharge. The evidence reviewed primarily focused on updates in the global epidemiology of BV, risk factors for BV, data supportive of sexual transmission of BV-associated bacteria, BV molecular diagnostic tests, and novel treatment regimens. Additionally, recent literature on alcohol abstinence in the setting of 5-nitroimidazole use was reviewed.

The Role of Antimicrobial Resistance in Refractory and Recurrent Bacterial Vaginosis and Current Recommendations for Treatment

Bacterial vaginosis (BV), the most common cause of vaginal discharge, is characterized by a shift in the vaginal microbiota from Lactobacillus species dominance to a diverse array of facultative and strict anaerobic bacteria which form a multi-species biofilm on vaginal epithelial cells. The rate of BV recurrence after therapy is high, often >60%. The BV biofilm itself likely contributes to recurrent and refractory disease after treatment by reducing antimicrobial penetration. However, antimicrobial resistance in BV-associated bacteria, including those both within the biofilm and the vaginal canal, may be the result of independent, unrelated bacterial properties. In the absence of new, more potent antimicrobial agents to eradicate drug-resistant pathogenic vaginal microbiota, treatment advances in refractory and recurrent BV have employed new strategies incorporating combination therapy. Such strategies include the use of combination antimicrobial regimens as well as alternative approaches such as probiotics and vaginal fluid transfer. Our current recommendations for the treatment of refractory and recurrent BV are provided.

Cysteine dependence of Lactobacillus iners is a potential therapeutic target for vaginal microbiota modulation

Vaginal microbiota composition affects many facets of reproductive health. Lactobacillus iners-dominated microbial communities are associated with poorer outcomes, including higher risk of bacterial vaginosis (BV), compared with vaginal microbiota rich in L. crispatus. Unfortunately, standard-of-care metronidazole therapy for BV typically results in dominance of L. iners, probably contributing to post-treatment relapse. Here we generate an L. iners isolate collection comprising 34 previously unreported isolates from 14 South African women with and without BV and 4 previously unreported isolates from 3 US women. We also report an associated genome catalogue comprising 1,218 vaginal Lactobacillus isolate genomes and metagenome-assembled genomes from >300 women across 4 continents. We show that, unlike L. crispatus, L. iners growth is dependent on L-cysteine in vitro and we trace this phenotype to the absence of canonical cysteine biosynthesis pathways and a restricted repertoire of cysteine-related transport mechanisms. We further show that cysteine concentrations in cervicovaginal lavage samples correlate with Lactobacillus abundance in vivo and that cystine uptake inhibitors selectively inhibit L. iners growth in vitro. Combining an inhibitor with metronidazole promotes L. crispatus dominance of defined BV-like communities in vitro by suppressing L. iners growth. Our findings enable a better understanding of L. iners biology and suggest candidate treatments to modulate the vaginal microbiota to improve reproductive health for women globally.

Bacterial Vaginosis: What Do We Currently Know?

The vaginal microbiome is a well-defined compartment of the human microbiome. It has unique conditions, characterized by the dominance of one bacterial species, the Lactobacilli. This microbiota manifests itself by a low degree of diversity and by a strong dynamic of change in its composition under the influence of various exogenous and endogenous factors. The increase in diversity may paradoxically be associated with dysbiosis, such as bacterial vaginosis (BV). BV is the result of a disturbance in the vaginal ecosystem; i.e., a sudden replacement of Lactobacilli by anaerobic bacteria such as Gardnerella vaginalis, Atopobium vaginae, Ureaplasma urealyticum, Mycoplasma hominis, and others. It is the most common cause of vaginal discharge in women of childbearing age, approximately 30% of all causes. The etiology of this dysbiosis remains unknown, but its health consequences are significant, including obstetrical complications, increased risk of sexually transmitted infections and urogenital infections. Its diagnosis is based on Amsel’s clinical criteria and/or a gram stain based on the Nugent score. While both of these methods have been widely applied worldwide for approximately three decades, Nugent score are still considered the “gold standard” of BV diagnostic tools. Given the limitations of these tools, methods based on molecular biology have been developed as alternative rational strategies for the diagnosis of BV. The treatment of BV aims at restoring the balance of the vaginal flora to stop the proliferation of harmful microorganisms. Prescription of antibiotics such as metronidazole, clindamycin, etc. is recommended. Faced with the considerable uncertainty about the cause of BV, the high rate of recurrence, the unacceptable treatment options, and clinical management which is often insensitive and inconsistent, research on this topic is intensifying. Knowledge of its composition and its associated variations represents the key element in improving the therapeutic management of patients with the most suitable treatments possible.

A Prospective, Open-Label Pilot Study of Concurrent Male Partner Treatment for Bacterial Vaginosis

Up to 50% of women receiving first-line antibiotics for bacterial vaginosis (BV) experience recurrence within 12 weeks. Evidence suggests that reinfection from an untreated regular sexual partner contributes to recurrence. We conducted a pilot study of 34 heterosexual couples to describe the impact of concurrent partner treatment on the composition of the genital microbiota over a 12-week period. We also determined the acceptability and tolerability of concurrent partner treatment and obtained preliminary estimates of the efficacy of the intervention to inform a randomized controlled trial (RCT). Women received first-line antibiotic treatment for BV (i.e., oral metronidazole or intravaginal clindamycin), and their male partner received oral metronidazole, 400 mg, and 2% clindamycin cream applied topically to penile skin, both twice daily for 7 days. The genital microbiota was characterized at three anatomical sites (women, vaginal; men, cutaneous penile and first-pass urine [representing the urethra]) using 16S rRNA gene sequencing. Immediately posttreatment, concurrent partner treatment significantly reduced the abundance of BV-associated bacteria (false-discovery rate [FDR] corrected P value < 0.05) and altered the overall microbiota composition of all three anatomical sites (P = 0.001). Suppression of BV-associated bacteria was sustained in the majority (81%) of women over the 12-week period (FDR P value < 0.05), despite BV-associated bacteria reemerging at both genital sites in men. In this cohort of women at high risk for recurrence, five recurred within 12 weeks of treatment (17%; 95% confidence interval [CI], 6 to 34%). Importantly, men tolerated and adhered to combination therapy. Our findings provide support for an RCT of combined oral and topical male partner treatment for BV. IMPORTANCE Recurrence of BV following standard treatment is unacceptably high. Posttreatment recurrence is distressing for women, and it imposes a considerable burden on the health care system. Recurrences result in multiple presentations to clinical services and repeated antibiotic use, and the associated obstetric and gynecological sequelae are significant. New treatments to improve long-term BV cure are urgently needed. Here, we used 16S rRNA gene sequencing to investigate changes in the microbiota composition at three genital sites (vagina, penile skin, and male urethra) of heterosexual couples undergoing concurrent partner treatment for bacterial vaginosis (BV). We found that concurrent partner treatment immediately and significantly altered the composition of the genital microbiota of both partners, with a reduction in BV-associated bacteria seen at all three sites. BV cure at 12 weeks posttreatment was higher than expected. These microbiological data provide evidence for continued investigation of partner treatment as a strategy to improve BV cure.

Bacterial vaginosis: drivers of recurrence and challenges and opportunities in partner treatment

Bacterial vaginosis (BV) is the most common vaginal dysbiosis to affect women globally, yet an unacceptably high proportion of women experience BV recurrence within 6 months of recommended antibiotic therapy. The low rate of sustained cure highlights our limited understanding of the pathogenesis of BV recurrence, which has been attributed to possible persistence and re-emergence of BV-associated bacteria (BVAB) or a BV-associated biofilm following antimicrobials and/or reinfection occurring from sexual partners.There is a robust body of evidence to support the exchange of bacteria between partners during sexual activity, and while the hypothesis that women treated for BV are subsequently reinfected with BVAB following sex with an untreated sexual partner is not new, failure of past partner treatment trials has eroded confidence in this concept. If reinfection is a key driver of recurrence, current antimicrobial regimens directed to women alone are unlikely to achieve a high level of sustained cure, and the approach of partner treatment to reduce reinfection is justified. In this manuscript, we present the molecular and epidemiological evidence that underlies the hypothesis that BV is sexually transmitted, and summarise why research that continues to consider sexual partnerships is necessary. We also outline the significant barriers and challenges that we have identified while undertaking partner treatment studies, and we discuss the factors that impact on our ability to determine their effectiveness.Ultimately, the pathogenesis of BV recurrence is likely to be multifaceted and not attributable to a single mechanism in all women. If we are to achieve sustained cure for women, it is likely that combined and individualised approaches to eradicate BVAB, support an optimal vaginal microbiome, and prevent reinfection from partners will be required.

Sexually Transmitted Infections Treatment Guidelines, 2021

These guidelines for the treatment of persons who have or are at risk for sexually transmitted infections (STIs) were updated by CDC after consultation with professionals knowledgeable in the field of STIs who met in Atlanta, Georgia, June 11–14, 2019. The information in this report updates the 2015 guidelines. These guidelines discuss 1) updated recommendations for treatment of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis; 2) addition of metronidazole to the recommended treatment regimen for pelvic inflammatory disease; 3) alternative treatment options for bacterial vaginosis; 4) management of Mycoplasma genitalium; 5) human papillomavirus vaccine recommendations and counseling messages; 6) expanded risk factors for syphilis testing among pregnant women; 7) one-time testing for hepatitis C infection; 8) evaluation of men who have sex with men after sexual assault; and 9) two-step testing for serologic diagnosis of genital herpes simplex virus. Physicians and other health care providers can use these guidelines to assist in prevention and treatment of STIs.