Scientific Reports - Computational approach for drug discovery against Gardnerella vaginalis in quest for safer and effective treatments for bacterial vaginosis

Background Bacterial vaginosis (BV) is the most common vaginal infection in reproductive-age women. It is associated with adverse pregnancy complications, such as preterm birth and low birth weight, in addition to an increased risk of acquisition of HIV and sexually transmitted infections. BV is characterized by a vaginal dysbiosis, involving loss of protective Lactobacillus species (including L. crispatus) and overgrowth of facultative and strict anaerobic bacteria, with Gardnerella species playing a predominant role. However, despite extensive research on BV pathogenesis, its etiology remains unclear, and the sequence of events leading to the displacement of lactobacilli by anaerobic bacteria in women has not yet been fully elucidated. Until 2019, all bacteria belonging to the Gardnerella genus were considered part of the species G. vaginalis. However, it is now recognized that different Gardnerella species exist, each with varying virulence potentials. Recent data have shown that multiple subgroups of Gardnerella spp. are frequently detected simultaneously in the vaginal microbiota of women with BV. With this in mind, we aimed to test the hypothesis that different combinations of known Gardnerella species, isolated from the vaginal microbiota of women with BV, have an enhanced ability to compete against Lactobacillus crispatus, pre-adhered to HeLa cells, thereby facilitating the early stages of BV development. Methods Adhesion assays of dual combinations of Gardnerella spp. (G. vaginalis, G. leopoldii, G. swidsinskii, G. piotii) were performed on an in vitro model of HeLa cells, covered with and without L. crispatus. Quantification of the species used in our assays was subsequently performed using quantitative polymerase chain reaction (qPCR). Results Our results revealed synergy between different Gardnerella spp., demonstrating their ability to overcome the presumed protective effect of L. crispatus, thereby creating favorable conditions for the development of a polymicrobial biofilm characteristic of BV. The combination of G. vaginalis and G. leopoldii showed the greatest synergistic effect on initial adhesion to HeLa cells while the combination of G. leopoldii and G. swidsinskii had the greatest ability to reduce L. crispatus colonization. Conclusions Although this in vitro study does not unequivocally prove that BV is initiated by the disruption of normal vaginal microbiota by Gardnerella spp., it strongly supports this possibility, contributing to a better understanding of BV etiology.

The vaginal microbiome is central to reproductive health, yet large-scale studies in East Asian populations remain scarce. Here, we characterized the vaginal microbiota of 6423 Chinese women of repro...

Bacterial vaginosis (BV) is a vaginal dysbiosis characterized by polymicrobial communities of BV-associated bacteria (BVAB) adhered to the vaginal epithelium. Despite decades of research, its etiology remains unknown. We aimed to investigate BV biofilm formation over time among women who developed incident BV (iBV) using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), focusing on 3 key BVAB (Gardnerella species, Prevotella bivia, and Fannyhessea vaginae).MethodsHeterosexual, nonpregnant women ages 18–45 with optimal vaginal microbiota were enrolled to self-collect twice-daily vaginal specimens for 60 days. iBV was defined as a Nugent score of 7–10 on ≥4 consecutive specimens. For women who developed iBV (cases), Gardnerella spp., P. bivia, and F. vaginae were visualized and quantified by PNA-FISH for up to 14 days prior to iBV, the day of iBV, and 3 days post-iBV. Cases were matched to women maintaining optimal vaginal microbiota (controls) based on age, race, and contraceptive method. Control specimens were matched to case specimens by day of menses.ResultsAmong 135 women enrolled, 18 developed iBV and were matched to 18 controls. Pooled median Gardnerella spp. counts significantly increased starting 5 days before iBV, while pooled median F. vaginae counts significantly increased on the day of iBV diagnosis. In contrast, pooled median P. bivia counts were not significantly different between groups.ConclusionsThese data suggest that Gardnerella spp. are early colonizers of the BV biofilm while F. vaginae is a secondary colonizer. P. bivia was not found to be significantly different between iBV case and control specimens.

Bacterial vaginosis (BV) is a vaginal dysbiosis characterized by polymicrobial communities of BV-associated bacteria (BVAB) adhered to the vaginal epithelium.

Bacterial vaginosis (BV) is a vaginal dysbiosis characterized by polymicrobial communities of BV-associated bacteria (BVAB) adhered to the vaginal epithelium. Despite decades of research, its etiology remains unknown. We aimed to investigate BV biofilm formation over time among women who developed incident BV (iBV) using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), focusing on three key BVAB (Gardnerella species, Prevotella bivia, and Fannyhessea vaginae).MethodsHeterosexual, non-pregnant women ages 18-45 with optimal vaginal microbiota were enrolled to self-collect twice-daily vaginal specimens for 60 days. iBV was defined as a Nugent score of 7-10 on ≥4 consecutive specimens. For women who developed iBV (cases), Gardnerella spp., P. bivia, and F. vaginae were visualized and quantified by PNA-FISH for up to 14 days prior to iBV, the day of iBV, and 3 days post-iBV. Cases were matched to women maintaining optimal vaginal microbiota (controls) based on age, race, and contraceptive method. Control specimens were matched to case specimens by day of menses.ResultsAmong 135 women enrolled, 18 developed iBV and were matched to 18 controls. Pooled median Gardnerella spp. counts significantly increased starting 5 days before iBV, while pooled median F. vaginae counts significantly increased on the day of iBV diagnosis. In contrast, pooled median P. bivia counts were not significantly different between groups.ConclusionThese data suggest that Gardnerella spp. are early colonizers of the BV biofilm while F. vaginae is a secondary colonizer. P. bivia was not found to be significantly different between iBV case and control specimens.

AbstractSchistosoma haematobium infection may impair female genital mucosal antiviral defense. We sought to determine whether women with S. haematobium infection had higher odds of high-risk human papillomavirus (HR-HPV) persistence, a pre-requisite to cervical cancer. We also examined cervicovaginal dysbiosis, which has been linked to HR-HPV persistence and schistosome infection. In 96 Tanzanian women with baseline and 9-12-month follow-up samples, we performed HPV genotyping, schistosome antigen quantification, and 16S rRNA sequencing. Both S. haematobium (Odds ratio (OR): 4.7 [1.3-16.5], p=0.017) and Gardnerella-dominant microbiome (p=0.049) were associated with HR-HPV persistence, suggesting these factors may contribute to high cervical cancer rates in Africa.

Genetic manipulation is a fundamental process in the study of bacterial pathogenesis. The ability to make mutations and complements is necessary for definitive identification of virulence genes, and the ability to make unmarked mutations is preferable in these studies (1). Certain bacterial pathogens were considered genetically intractable for many years, such as Mycobacterium tuberculosis or Chlamydia trachomatis, and studies of their virulence mechanisms necessarily focused on epidemiology, immunology, cell biology in the host, and proteomic or transcriptomic analyses (2, 3). Those classic cases were eventually resolved by the discovery of effective transduction, natural transformation, and chemical transformation methods, greatly facilitating the identification of virulence factors (4–7). Gardnerella species have similarly been considered genetically intractable, and like M. tuberculosis and C. trachomatis, Gardnerella have an unusual cell envelope. Similar to other Actinobacteria, Gardnerella are generally considered gram-positive, but stain gram-variable because of their unusual and incompletely characterized envelope (8).