Allison (Aslin) Mighell

 Introduction. Bacterial vaginosis (BV) is a microbial imbalance of the vaginal flora characterized by the absence of normally dominant lactobacilli and overgrowth of complex communities dominated by gram-negative bacteria.¹ BV is the most common disorder of the female reproductive tract that is characterized by malodorous vaginal discharge, increase in vaginal pH, and clue cells on vaginal swab specimen.² When bacterial vaginosis occurs during pregnancy, serious sequelae may result including late miscarriage and preterm birth. Methods. With the intent to find studies associated with the pathogenicity of Gardnerella vaginalis in Bacterial Vaginosis, PubMed was utilized as a database for eligible studies. All articles were published within the past 5 years and were searched using the following keywords, in multiple combinations: “vaginal microbiome”, “pregnancy”, “G. vaginalis”, “Gardnerella vaginalis”, and “bacterial vaginosis”. Included articles were directed related to the purpose of investigating both the pathogenicity of Gardnerella vaginalis and this organism’s possible serious sequelae during pregnancy. Results. Upon review of selected articles, two main mechanisms were elucidated for incidence of bacterial vaginosis associated with serious sequelae during pregnancy. G. vaginalis uses sialidase enzymatic activity to degrade host mucosa, as well as, immunoglobulins.³ Through the degradation of the mucosa in the vaginal wall, the ability to form a biofilm is increased leading to a higher incidence of disease and ascending infection.³ This enzymatic activity is resistant to mild proteolysis and also uses degraded products as surface molecules to evade the immune system.¹ Upregulation of inflammatory cytokines within the vaginal canal and cervix also contribute to bacterial vaginosis. Sequelae during pregnancy can partly be contributed to the greater cytokine production in the endocervix, as well as increase release of hBD2, a lymphocyte chemoattractant.¹ Conclusions. In conclusion, studies have shown that BV due to G. vaginalis, leads to potential sequelae, including late miscarriage and preterm birth, when sialidase activity interrupts the vaginal mucosa and cytokine release leads to immune defense mechanisms within the endocervix region.^2,3 There is room for advancement within treatment of this disease to reduce obstetric and neonatal negative outcomes.⁴

1. Eade CR, Diaz C, Wood MP, et al. Identification and Characterization of Bacterial Vaginosis-Associated Pathogens Using a Comprehensive Cervical-Vaginal Epithelial Coculture Assay. Ratner AJ, ed. PLoS ONE. 2012;7(11):e50106. doi:10.1371/journal.pone.0050106.
2. Gilbert NM, Lewis WG, Lewis AL. Clinical Features of Bacterial Vaginosis in a Murine Model of Vaginal Infection with Gardnerella vaginalis. Ratner AJ, ed. PLoS ONE. 2013;8(3):e59539. doi:10.1371/journal.pone.0059539.
3. Hardy L, Jespers V, Van den Bulck M, et al. The presence of the putative Gardnerella vaginalis sialidase A gene in vaginal specimens is associated with bacterial vaginosis biofilm. Mitchell C, ed. PLoS ONE. 2017;12(2):e0172522. doi:10.1371/journal.pone.0172522.
4. Bretelle F, Fenollar F, Baumstarck K, et al. Screen-and-treat program by point-of-care of Atopobium vaginae and Gardnerella vaginalis in preventing preterm birth (AuTop trial): study protocol for a randomized controlled trial. Trials. 2015;16:470. doi:10.1186/s13063-015-1000-y.