Daniela Machado

Bacterial Vaginosis Biofilms: Challenges to Current Therapies and Emerging Solutions

Bacterial vaginosis (BV) is the most common genital tract infection in women during their reproductive years and it has been associated with serious health complications, such as preterm delivery and acquisition or transmission of several sexually transmitted agents. BV is characterized by a reduction of beneficial lactobacilli and a significant increase in number of anaerobic bacteria, including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp., Bacteroides spp. and Prevotella spp.. Being polymicrobial in nature, BV etiology remains unclear. However, it is certain that BV involves the presence of a thick vaginal multi-species biofilm, where G. vaginalis is the predominant species. Similar to what happens in many other biofilm-related infections, standard antibiotics, like metronidazole, are unable to fully eradicate the vaginal biofilm, which can explain the high recurrence rates of BV. Furthermore, antibiotic therapy can also cause a negative impact on the healthy vaginal microflora. These issues sparked the interest in developing alternative therapeutic strategies. This review provides a quick synopsis of the currently approved and available antibiotics for BV treatment while presenting an overview of novel strategies that are being explored for the treatment of this disorder, with special focus on natural compounds that are able to overcome biofilm-associated antibiotic resistance.

Escherichia coli and Enterococcus faecalis are able to incorporate and enhance a pre-formed Gardnerella vaginalis biofilm

Gardnerella vaginalis is the most frequent microorganism found in bacterial vaginosis (BV), while Escherichia coli and Enterococcus faecalis are amongst the most frequent pathogens found in urinary tract infections (UTIs). This study aimed to evaluate possible interactions between UTIs pathogens and G. vaginalis using an in vitro dual-species biofilm model. Our results showed that dual-species biofilms reached significantly higher bacterial concentration than monospecies biofilms. Moreover, visualization of dual-populations species in the biofilms, using the epifluorescence microscopy, revealed that all of the urogenital pathogens coexisted with G. vaginalis. In conclusion, our work demonstrates that uropathogens can incorporate into mature BV biofilms.

Optimization of culture conditions for Gardnerella vaginalis biofilm formation

Bacterial vaginosis is the leading vaginal disorder in women in reproductive age. Although bacterial vaginosis is related with presence of a biofilm composed predominantly by Gardnerella vaginalis, there has not been a detailed information addressing the environmental conditions that influence the biofilm formation of this bacterial species. Here, we evaluated the influence of some common culture conditions on G. vaginalis biofilm formation, namely inoculum concentration, incubation period, feeding conditions and culture medium composition. Our results showed that culture conditions strongly influenced G. vaginalis biofilm formation and that biofilm formation was enhanced when starting the culture with a higher inoculum, using a fed-batch system and supplementing the growth medium with maltose.

Prevalence of bacterial vaginosis in Portuguese pregnant women and vaginal colonization by Gardnerella vaginalis

Background We aimed to determine the prevalence of vaginal colonization by Gardnerella vaginalis and of bacterial vaginosis (BV) in Portuguese pregnant women, and to identify risk factors for BV and G. vaginalis colonization in pregnancy. Methods A cross-sectional study was conducted among pregnant women aged ≥ 18 years who were attending in two public hospitals of the Northwest region of Portugal. Epidemiological data was collected by anonymous questionnaire. BV was diagnosed by Nugent criteria and G. vaginalis presence was identified by polymerase chain reaction. Crude associations between the study variables and BV or G. vaginalis colonization were quantified by odds ratios (ORs) and their 95% confidence intervals (CIs). Results The prevalences of BV and of G. vaginalis colonization among Portuguese pregnant women were 3.88% and 67.48%, respectively. Previous preterm delivery and colonization by G. vaginalis were factors with very high OR, but only statistically significant for a 90% CI. Conversely, higher rates of G. vaginalis colonization were found in women with basic educational level (OR = 2.77, 95% CI [1.33–5.78]), during the second trimester of pregnancy (OR = 6.12, 95% CI [1.80–20.85]) and with BV flora (OR = 8.73, 95% CI [0.50–153.60]). Discussion Despite the lower number of women with BV, prevalence ratios and association with risk factors were similar to recent European studies. However, the percentage of healthy women colonized by G. vaginalis was significantly higher than many previous studies, confirming that G. vaginalis colonization does not always lead to BV development.

Thymbra capitata essential oil as potential therapeutic agent against Gardnerella vaginalis biofilm-related infections

AIM To evaluate the antibacterial activity of Thymbra capitata essential oil and its main compound, carvacrol, against Gardnerella vaginalis grown planktonically and as biofilms, and its effect of vaginal lactobacilli. MATERIALS & METHODS Minimal inhibitory concentration, minimal lethal concentration determination and flow cytometry analysis were used to assess the antibacterial effect against planktonic cells. Antibiofilm activity was measured through quantification of biomass and visualization of biofilm structure by confocal laser scanning microscopy. RESULTS T. capitata essential oil and carvacrol exhibited a potent antibacterial activity against G. vaginalis cells. Antibiofilm activity was more evident with the essential oil than carvacrol. Furthermore, vaginal lactobacilli were significantly more tolerant to the essential oil. CONCLUSION T. capitata essential oil stands up as a promising therapeutic agent against G. vaginalis biofilm-related infections.