Effect of postbiotics on biofilm formation and gene expression in Candida spp. isolates from patients with recurrent vulvovaginal candidiasis

First-line treatment for vulvovaginal candidiasis (VVC) has reduced efficacy in patients with recurrent VVC (RVVC), prompting the search for therapeutic alternatives such as probiotics. Recently, postbiotics (cellular components and metabolites derived from probiotics) have gained relevance because they offer similar benefits to probiotics without the risks associated with live microorganisms. This study aimed to evaluate the anti-biofilm effect of cell-free supernatants (CFSs) derived from probiotic strains against Candida spp. isolates from patients with RVVC, as well as their impact on the expression of genes associated with biofilm formation. Therefore, the anti-biofilm activity of CFSs from Lacticaseibacillus rhamnosus DM-UFMG 63, Bifidobacterium longum 5,1A and Lactobacillus acidophilus NCFM SD 5221 was evaluated in 40 Candida spp. isolates. The CFSs from L. acidophilus NCFM SD 5221 and Lc. rhamnosus 63 were analyzed using the XTT assay, and their effect on gene expression was measured by qPCR. At an estimated protein concentration of ∼200μg/mL, these CFSs significantly inhibited biofilm formation by approximately 50% (p<0.01)). This phenotypic effect correlated with the downregulation of key biofilm-associated genes (ALS3, HWP1, EFG1, TEC1, and UME6), alongside a concomitant upregulation of the transcriptional repressor NRG1. The findings of this study demonstrate that CFSs derived from Lc. rhamnosus DM-UFMG 63 and L. acidophilus NCFM SD 5221 exhibit significant antagonistic activity against biofilm formation in clinical isolates from patients with RVVC. Consequently, these cell-free supernatants represent a promising therapeutic and prophylactic alternative for the management of recurrent vulvovaginal candidiasis.