A non-antibiotic antimicrobial drug, a biological bacteriostatic agent, is useful for treating aerobic vaginitis, bacterial vaginosis, and vulvovaginal candidiasis

Abstract

Background: Vaginitis is a common infection in women, with approximately 75% of women experiencing at least one episode during their lifetime. Although antimicrobial agents are widely used to treat vaginitis, recurrent vaginitis occurs in some patients. Resistance to these agents is the major cause of recurrent vaginitis. Therefore, there is an urgent need to develop novel drugs.

Methods: We investigated the efficacy of a new biological bacteriostatic agent (BBA), composed of lysozyme, phytoalexin, chitosan oligosaccharide, sinensetin, 18β/20α-glycyrrhizin, and betaine, against vaginitis using in vitro and in vivo studies. First, we evaluated the antibacterial effects of BBA against 13 microbial strains commonly present in aerobic vaginitis, bacterial vaginosis, vulvovaginal candidiasis, and healthy vaginas. Second, we assessed the safety of various doses of BBA administered orally for 4 weeks in female mice. Third, we examined the in vivo anti-proliferative and anti-inflammatory effects of BBA in Candida albicans-, Candida glabrata-, and Gardnerella-induced vaginitis models. Finally, we evaluated the anti-vaginitis effect of a BBA gel prepared with 0.5% (w/v) ammonium acryloyldimethyltaurate/Vp copolymer.

Results: BBA effectively suppressed the growth of the main causative pathogens of vaginitis in vitro. BBA, either undiluted or diluted two-fold, inhibited all microorganisms cultured for 8 h. No obvious organ damage was detected when BBA was administered to mice. Both BBA alone and 70% BBA in a gel formulation effectively inhibited the proliferation of C. albicans, C. glabrata, and Gardnerella in vaginal lavage samples and alleviated tissue inflammation in mice with vaginitis. The 70% BBA gel performed better than BBA alone at treating vaginitis in mice infected with Gardnerella vaginalis.

Conclusion: BBA alone and a 70% BBA gel inhibited the growth of pathogens and effectively alleviated inflammation caused by C. albicans, C. glabrata, and G. vaginalis.

Keywords: antimicrobial drug; biological bacteriostatic agent; non-antibiotic; vaginal infections; vaginitis.

Figure 1

Antibacterial effect of BBA. BBA, biological bacteriostatic agent. (A) Escherichia coli. (B) Candida albican. (C) Enterococcus faecalis. (D) Streptococcus agalactiae. (E) Staphylococcus aureus. (F) Streptococcus anginosus. (G) Candida glabrata. (H) Atopobium vaginae. (I) Gardnerella vaginalis. (J) Lactobacillus crispatus. (K) Lactobacillus jensenii. (L) Lactobacillus gasseri. (M) Lactobacillus inner.

Figure 2

Effects of BBA on organ index values. (A) Average body weight. (B) Organ index values after intragastric administration of BBA. (C–E) Oocyte maturation and spindle assembly were not affected by BBA. Bar, 20 μm. The error bars are standard deviations. BBA, biological bacteriostatic agent.

Figure 3

Efficacy of BBA against C. albicans-induced vaginitis in mice. (A–C) Levels of IL-1β, IL-6, and IL-17 in vaginal tissues. (D) HE staining of vaginal tissues. Green arrow, cavitation; black arrow, epithelial cells. The same letter indicates no significant difference between groups; different letters indicate a significant difference between groups. The error bars are standard deviations. BBA, biological bacteriostatic agent; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-17, interleukin-17; HE staining, hematoxylin and eosin staining.

Figure 4

Efficacy of BBA against C. glabrata-induced vaginitis. (A–C) Concentrations of IL-1β, IL-6, and IL-17 in vaginal tissues. (D) HE staining of vaginal tissues. Green arrow, cavitation; black arrow, epithelial cells. The same letter indicates no significant difference between groups; different letters indicate a significant difference between groups. The error bars are standard deviations. BBA, biological bacteriostatic agent; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-17, interleukin-17; HE, hematoxylin and eosin.

Figure 5

BBA partly improved Gardnerella vaginalis-induced inflammation. (A–C) Concentrations of IL-1β, IL-6, and IL-17 in vaginal tissues. (D) HE staining of vaginal tissues. Green arrow, cavitation; black arrow, epithelial cells. The same letter indicates no significant difference between groups; different letters indicate a significant difference between groups. The error bars are standard deviations. BBA, biological bacteriostatic agent; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-17, interleukin-17; HE, hematoxylin and eosin.

Figure 6

Efficacy of a 70% BBA gel against VVC. (A–F) Concentrations of IL-1β, IL-6, and IL-17 in vaginal tissues of mice with C. albicans- and C. glabrata-induced vaginitis. (D) Vaginal tissues were stained to further investigate the role of the 70% BBA gel in the treatment of VVC. Green arrow, cavitation; black arrow, epithelial cells. The same letter indicates no significant difference between groups; different letters indicate a significant difference between groups. The error bars are standard deviations. BBA, biological bacteriostatic agent; VVC, vulvovaginal candidiasis; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-17, interleukin-17; C. albicans, Candida albicans; C. glabrata, Candida glabrata. (G,H) HE staining of vaginal tissues from mice with C. albicans- and C. glabrata-induced vaginitis.

Figure 7

70% BBA gel alleviated Gardnerella vaginalis-induced inflammation. (A–C) Concentrations of IL-1β, IL-6, and IL-17 in vaginal tissues. (D) Representative images showing the effects of the 70% BBA gel on vaginal inflammation induced by Gardnerella vaginalis. Green arrow, cavitation; black arrow, epithelial cells. The same letter indicates no significant difference between groups; different letters indicate a significant difference between groups. The error bars are standard deviations. BBA, biological bacteriostatic agent; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-17, interleukin-17.