Clue Cells and Pseudo Clue Cells in Different Morphotypes of Bacterial Vaginosis

Interpretation of vaginal metagenomic characteristics in different types of vaginitis

Although vaginitis is closely related to vaginal microecology in females, the precise composition and functional potential of different types of vaginitis remain unclear. Here, metagenomic sequencing was applied to analyze the vaginal flora in patients with various forms of vaginitis, including cases with a clue cell proportion ranging from 1% to 20% (Clue1_20), bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC (VVC_BV). Our results identified Prevotella as an important biomarker between BV and Clue1_20. Moreover, a gradual decrease was observed in the relative abundance of shikimic acid metabolism associated with bacteria producing indole as well as a decline in the abundance of Gardnerella vaginalis in patients with BV, Clue1_20, and healthy women. Interestingly, the vaginal flora of patients in the VVC_BV group exhibited structural similarities to that of the VVC group, and its potentially functional characteristics resembled those of the BV and VVC groups. Finally, Lactobacillus crispatus was found in high abundance in healthy samples, greatly contributing to the stability of the vaginal environment. For the further study of L. crispatus, we isolated five strains of L. crispatus from healthy samples and evaluated their capacity to inhibit G. vaginalis biofilms and produce lactic acid in vitro to select the potential probiotic candidate for improving vaginitis in future clinical studies. Overall, we successfully identified bacterial biomarkers of different vaginitis and characterized the dynamic shifts in vaginal flora between patients with BV and healthy females. This research advances our understanding and holds great promise in enhancing clinical approaches for the treatment of vaginitis.

IMPORTANCE

Vaginitis is one of the most common gynecological diseases, mostly caused by infections of pathogens such as Candida albicans and Gardnerella vaginalis. In recent years, it has been found that the stability of the vaginal flora plays an important role in vaginitis. Furthermore, the abundant Lactobacillus-producing rich lactic acid in the vagina provides a healthy acidic environment such as Lactobacillus crispatus. The metabolites of Lactobacillus can inhibit the colonization of pathogens. Here, we collected the vaginal samples of patients with bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC to discover the differences and relationships among the different kinds of vaginitis by metagenomic sequencing. Furthermore, because of the importance of L. crispatus in promoting vaginal health, we isolated multiple strains from vaginal samples of healthy females and chose the most promising strain with potential probiotic benefits to provide clinical implications for treatment strategies.

Molecular Testing for the Diagnosis of Bacterial Vaginosis

Previously established diagnostic approaches for the diagnosis of bacterial vaginosis (BV), such as the Amsel criteria or the Nugent scoring system, do not always correspond to modern trends in understanding the etiology and pathogenesis of polymicrobial conditions. Inter-examiner variability and interpretation of data complicate the wet mount microscopy method. Gram staining of smears does not always provide reliable information regarding bacterial taxa, biofilms, or vaginal dysbiosis. Therefore, the introduction of molecular techniques into clinical practice is extremely relevant. Molecular approaches allow not only the diagnosis of BV but also provide an assessment of microbial composition, which is especially important in the differential diagnosis of vaginal infections. The current review represents an expert opinion on BV diagnosis and is based on extensive experience in the field of vaginal infection diagnosis and treatment.

Bacterial Vaginosis: Guideline of the DGGG, OEGGG and SGGG (S2k-Level, AWMF Registry No. 015/028, June 2023)

Aim This official guideline was coordinated and published by the DGGG, OEGGG and SGGG with the involvement of additional professional societies. The aim of the guideline is to evaluate the relevant literature and use it to provide a consensus-based overview of the diagnosis and management of bacterial vaginosis. Methods This S2k-guideline was developed by representative members from different medical professional societies on behalf of the guidelines commission of the above-listed societies using a structured consensus process. Recommendations This guideline provides recommendations on the diagnosis, management, counselling, prophylaxis, and other aspects related to bacterial vaginosis.

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.

State of the Art for Diagnosis of Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common cause of vaginal discharge among reproductive-age women. It is associated with multiple adverse health outcomes, including increased risk of acquisition of HIV and other sexually transmitted infections (STIs), in addition to adverse birth outcomes. While it is known that BV is a vaginal dysbiosis characterized by a shift in the vaginal microbiota from protective Lactobacillus species to an increase in facultative and strict anaerobic bacteria, its exact etiology remains unknown. The purpose of this minireview is to provide an updated overview of the range of tests currently used for the diagnosis of BV in both clinical and research settings. This article is divided into two primary sections: traditional BV diagnostics and molecular diagnostics. Molecular diagnostic assays, particularly 16S rRNA gene sequencing, shotgun metagenomic sequencing, and fluorescence in situ hybridization (FISH), are specifically highlighted, in addition to multiplex nucleic acid amplification tests (NAATs), given their increasing use in clinical practice (NAATs) and research studies (16S rRNA gene sequencing, shotgun metagenomic sequencing, and FISH) regarding the vaginal microbiota and BV pathogenesis. We also provide a discussion of the strengths and weaknesses of current BV diagnostic tests and discuss future challenges in this field of research.

Bacterial Vaginosis-Vaginal Polymicrobial Biofilms and Dysbiosis

BACKGROUND

Bacterial vaginosis (BV) is the most common genital disease worldwide in women of sexually active age, with a prevalence of 23-29%. Its traditional definition as dysbiosis, i.e., a disruption of the normal balance of the vaginal microbiota, with a massive increase of facultative and obligate anaerobic bacteria (mainly Gardnerella spp.) and a loss of lactobacilli, accurately describes the change in the vaginal microbiota, but does not explain the underlying pathophysiology.

METHODS

This review is based on information in pertinent articles retrieved by a selective literature search and on the authors' own research findings.

RESULTS

Fluorescent in situ hybridization (FISH) has revealed Gardnerella spp.-dominated polymicrobial vaginal biofilm as a cause of ascending gynecologic and pregnancy-related infections, preterm birth, and infertility in patients with BV. The biofilm-induced disturbance of epithelial homeostasis favors co-infection with pathogens of sexually transmitted infection (STI). Standard antibiotic therapy is ineffective against biofilms, and there is thus a recurrence rate above 50%. The characteristic biofilm can be followed as a diagnostic marker and is considered evidence of sexual transmission when heterosexual couples and ejaculate samples are examined. FISH studies have shown that, in addition to biofilm-related vaginosis, there are other dysbiotic changes in the vaginal microbiota that have not yet been characterized in detail. It is therefore justified to speak of a "bacterial vaginosis syndrome."

CONCLUSION

The simplistic view of BV as dysbiosis, characterizable by microscopic reference methods, has so far led to inadequate therapeutic success. An evaluation of molecular genetic testing methods that would be suitable for routine use and the development of therapeutic agents that are effective against biofilms are urgently needed if the "bacterial vaginosis syndrome" is to be effectively treated.

Therapeutic effects of fenticonazole on bacterial vaginosis in mice

Bacterial vaginitis (BV) is a syndrome of increased vaginal discharge, fishy smelling leucorrhea, and itching and burning vulva caused by the microecological imbalance in the vagina induced by mixture of Gardnerella vaginalis (GV) and some anaerobic bacteria. Fenticonazole, an imidazole derivative and antimicrobial compound, has been demonstrated to exert effective therapeutic effects in mixed vaginitis. Accordingly, our study was designed to explore the potential role of fenticonazole in GV-infected BV mouse models. Female C57/BL6 mice were injected intraperitoneally with β-estradiol 3 days before and on the day of GV infection to maintain a pseudoestrus state. On the day of infection, mice were intravaginally inoculated with 20 µl of a suspension of GV (6 × 106 CFU/ml). Fenticonazole was administered as 2% vaginal cream (0.2 mg each mouse) by intravaginal application once a day for 3 days beginning the day of infection. At day 3 postinfection, the mice were sacrificed and vaginal washes were harvested. GV proliferation and Lactobacillus content were calculated in the vaginal lavage. Neutrophil counts in the vaginal lavage were observed through Pap staining. Myeloperoxidase (MPO) activity and proinflammatory cytokine (TNF-α, IL-1β, IL-6, iNOS, COX2, and NF-κB) levels in vaginal tissues were measured by ELISA and western blotting. Vaginal tissues were stained by hematoxylin and eosin (H&E) to examine the exfoliation of vaginal epithelial cells. GV infection increased GV proliferation and neutrophil counts but reduced Lactobacillus content in the vaginal lavage, as well as enhanced MPO activity, proinflammatory cytokine levels, and the exfoliation of vaginal epithelial cells in vaginal tissues of BV mouse models. However, administration of fenticonazole significantly ameliorated the above phenomena. Fenticonazole greatly improves the symptoms of GV-induced BV in mouse models.