ABSTRACT
The emergence of resistance to antifungal drugs has made the treatment of vulvovaginal candidiasis (VVC) very challenging. Among natural substances, biosurfactants (BS) produced by Lactobacillus have gained increasing interest in counteracting Candida infections for their proven anti-adhesive properties and safety profile. In the present study, liposomes (LP-BS) or liposomes coated with hyaluronic acid (HY-LP-BS) were prepared in the presence of the BS isolated from the vaginal strain Lactobacillus crispatus BC1 and characterized in terms of size, ζ potential, stability and mucoadhesion. The anti-biofilm activity of free BS, LP-BS and HY-LP-BS was investigated against different Candida albicans and non-albicans strains (C. glabrata, C. lusitaniae, C. tropicalis, C. krusei and C. parapsilosis), clinically isolated from patients affected by VVC. The inhibition of biofilm formation and the dispersal of pre-formed biofilm were evaluated. The obtained phospholipid vesicles showed suitable size for vaginal application and good stability over the storage period. HY-LP-BS exhibited good mucoadhesive properties and the best anti-biofilm profile, both in preventing or limiting the surface colonization by a broad spectrum of Candida species. In conclusion, the formulation of a novel antifungal agent derived from the vaginal microbiota into mucoadhesive nanocarriers appears to be a promising biotherapeutic strategy to counteract vulvovaginal candidiasis.
ABSTRACT
OBJECTIVES: To evaluate the production of inhibitory substances against several urogenital pathogens and to determine the compatibility between selected vaginal lactobacilli to be considered as probiotic candidates. STUDY DESIGN: The inhibitory activity of 38 vaginal Lactobacillus strains against urogenital pathogens was assessed using the agar plate diffusion. METHOD: The production of hydrogen peroxide was determined by the semi-qualitative tetramethyl-benzidine-peroxidase assay and that of lactic acid by high performance liquid chromatography. Pre-selected lactobacilli were genetically identified by ribosomal 16S-DNA sequencing and used to determine the compatibility of strains. Correlation values between some inhibitory properties were calculated. RESULTS: 45% of the lactobacilli assayed inhibited the growth of various urogenital pathogens, except Candida albicans, mainly by the effect of organic acids. Even though 71% of the Lactobacillus strains produced hydrogen peroxide in the semi-qualitative test, the antimicrobial effect of the oxidative metabolite on pathogens was not detected under the experimental conditions assayed. On the other hand, the inhibition spectrum of salivaricin CRL 1328 was widened with respect to the one previously reported by our research team. With respect to the degree of interaction between the pre-selected lactobacilli, most of them showed inhibition of at least one strain, mainly due to the effects of both organic acids and hydrogen peroxide. CONCLUSION: Several lactobacilli that showed inhibitory activity against urogenital pathogens or produced hydrogen peroxide are compatible between them. Therefore, different potential combinations of strains are proposed for their inclusion in the design of probiotic products to be vaginally administered for the prevention of urogenital infections in women.
