IntroductionAntifungal agents are not always efficient in resolving vulvovaginal candidiasis (VVC), a common genital infection caused by the overgrowth ofCandidaspp., includingCandida albicans, or in preventing recurrent infections. Although lactobacilli (which are dominant microorganisms constituting healthy human vaginal microbiota) are important barriers against VVC, theLactobacillusmetabolite concentration needed to suppress VVC is unknown.MethodsWe quantitatively evaluatedLactobacillusmetabolite concentrations to determine their effect onCandidaspp., including 27 vaginal strains ofLactobacillus crispatus, L. jensenii, L. gasseri, Lacticaseibacillus rhamnosus, andLimosilactobacillus vaginalis, with inhibitory abilities against biofilms ofC. albicansclinical isolates.ResultsLactobacillusculture supernatants suppressed viable fungi by approximately 24%-92% relative to preformedC. albicansbiofilms; however, their suppression differed among strains and not species. A moderate negative correlation was found betweenLactobacilluslactate production and biofilm formation, but no correlation was observed between hydrogen peroxide production and biofilm formation. Both lactate and hydrogen peroxide were required to suppressC. albicansplanktonic cell growth.Lactobacillusstrains that significantly inhibited biofilm formation in culture supernatant also inhibitedC. albicansadhesion to epithelial cells in an actual live bacterial adhesion competition test.DiscussionHealthy human microflora and their metabolites may play important roles in the development of new antifungal agent againstC. albicans-induced VVC.