Antimicrobial Activity of a Vaginal Gel Formulation: Considerations Related to Vaginal Infection and Dysbiosis

Abstract

Many non-prescription preparations intended to treat or alleviate symptoms of vaginal infection are available in American and European markets, but many have scant preclinical or clinical research underpinning. Respecta®Balance Gel (RBG) is marketed as an adjunct to probiotic treatment and its relevant antimicrobial properties were studied. Key findings with the manufacturer-supplied gel showed reduced turbidity in broth-dilution tests by 50% against Candida albicans and Candida glabrata at RBG concentrations 0.2–0.4% of neat product, respectively. A 50% reduction in turbidity of Escherichia coli, Streptococcus agalactiae, Enterococcus faecalis ranged from 1.6–2.2% and Gardnerella vaginalis was shown by flow cytometry counts to undergo a 50% reduction at 0.3% RBG. Propidium iodide staining indicated a rapid reduction of cell integrity of G. vaginalis almost immediately while after 4 h 45% of E. coli cells were stained. The lactic acid in BHI inhibited bacteria and yeast at concentrations ranging from 0.2–1.8% but inhibition was not solely due to pH since a 1:4 dilution of RBG resulted in a pH near neutral (6.75). Other findings showed biofilm accumulation assessed after 10-days exposure of Candida spp. to RBG and was reduced by an average of one-third (community strains) to one-half (drug-resistant strains). One excipient of the RBG, disodium EDTA, inhibited the growth of bacteria and yeast at concentrations below those present in RBG and may accentuate the activity of the host defense factor, lactoferrin. We conclude that RBG is a potent inhibitor of vaginal microorganisms relevant to vaginitis or intrapartum infections and contains excipients that may contribute to its antimicrobial activity.

Calcitermin-Loaded Smart Gels Activity against Candida albicans: A Preliminary In Vitro Study

“…Remarkably, an increased antifungal activity by gel inclusion has been shown for several potential antifungal compounds other than Cal, confirming our present findings [57][58][59][60][61][62][63][64]. For instance metal ions [58], and conventional fungicides such as miconazole and voriconazole, showed an increased action by gel inclusion also in vivo, in animal models [62,64].…”

“…Several compounds of natural origin, such as tea tree or other oils, were reported to have a better antifungal activity when included in gel preparation [60]. In addition, gel formulations specifically addressed to treat vaginal dysbiosis (Respecta ® Balance Gel, RBG, marketed as an adjunct to probiotic treatment), showed a high inhibitory action against diverse Candida strains, including C. albicans and C. glabrata, as well as against Gram-negative and grampositive vaginal bacteria [59]. In this perspective, the behavior of Cal observed in this pilot study suggests that its inclusion in G18/0.4, may improve the peptide antimicrobial activity.…”

Anti-Candida and Anti-Inflammatory Properties of a Vaginal Gel Formulation: Novel Data Concerning Vaginal Infection and Dysbiosis

“…In this work, we tested the antifungal and anti-inflammatory properties of the vaginal gel RBG, a commercially available formulation used as an adjuvant in the treatment of vaginitis and vaginosis. The manufacturer claims that this gel helps to restore the physiological pH of the vaginal environment and to promote the growth of a balanced microbiota [ 41 ]. De Seta and Larsen recently showed in an in vitro study that RBG gel has antimicrobial properties against several microorganisms relevant to vaginal infections, such as Candida spp.…”

“…They concluded that the RBG formulation contains different components, including some excipients (such as EDTA), that can play a role in counteracting microbial growth. Although they ascribed the antimicrobial effect mainly to the lactic acid, they hypothesized an additional mechanistic and possible synergistic interaction between active components (polydextrose, lactic acid, farnesol) that may occur when RBG encounters vaginal fluids [ 41 ]. We excluded an effect of lactic acid in our experimental conditions since the pH of both RBG and the placebo formulation is around 7.4 when diluted from 1:150 to 1:300, and therefore superimposable to the pH of the medium alone.…”

“…It should be noted that RBG has been employed at a dilution of 1:300, i.e., the highest non-toxic dose for epithelial cells. This dilution is far below the doses tested by De Seta and Larsen to study the direct antimicrobial activity in vitro [ 41 ].…”