Cell-free supernatants of probiotic consortia impede hyphal formation and disperse biofilms of vulvovaginal candidiasis causing Candida in an ex-vivo model.

Vulvovaginal candidiasis is the second most common vaginal infection caused by drug-resistant Candida species that affects about 70-75% of reproductive age group women across the globe. As current-day antifungal drugs are ineffective against the biofilms formed by the drug-resistant Candida strains, several natural compounds and antagonistic microbes are being explored as alternative antifungal agents. In the present study, we investigated the anti-biofilm activity of Cell-Free Supernatant (CFS) extracted from the commercially available probiotics VSL-3 against the biofilms of Candida species and also evaluated their efficacy in curbing the yeast-to-hyphal transition. Various methodologies like crystal violet staining and scanning electron microscopy were used to study the effect of CFS against the biofilms formed by the species. The ability of CFS to interfere with yeast to hyphal transition in Candida was studied by colony morphology assay and visually confirmed with phase contrast microscopy. The potential of the CFS of the probiotics was also evaluated using goat buccal tissue, a novel ex-vivo model that mimics the vaginal environment. Moreover, the supernatant extracted from VSL-3 had the ability to down-regulate the expression of virulence genes of Candida from the biofilm formed over the ex-vivo model. These results emphasize the anti-fungal and anti-infective properties of the CFS of VSL-3 against drug-resistant Candida strains causing vulvovaginal candidiasis.

Chitosan-Coated Surgical Sutures Prevent Adherence and Biofilms of Mixed Microbial Communities.

Sutures are widely used materials for closing the surgical wounds, and being an inert material, sutures are often colonized with drug-resistant polymicrobial biofilms. Surgical site infection (SSI) is a hospital-acquired infection caused by bacteria and fungi specifically in the sutured sites. Although most of the currently available sutures possess antibacterial property, their ability to prevent biofilm colonization by polymicrobial communities is underexplored. So, the present study shows that extracted chitosan (EC) from crab shells prevented the adherence of Staphylococcus epidermidis and Candida albicans, the predominant members that exist as mixed species at the site of SSI. In comparison with a commercial chitosan, EC showed profound inhibition of slime formation and mixed species biofilm inhibition. Intriguingly, EC-coated sutures could inhibit the growth of both bacterial and fungal pathogens when comparing with a commercial triclosan-coated suture which was active only against the bacterial pathogen. Scanning electron microscopy results revealed inhibition of C. albicans hyphal formation by the EC-coated sutures that is a crucial virulence factor responsible for tissue invasiveness. Collectively, the results of the present study showed that EC from crab shells (discarded material as a recalcitrant biowaste) could be used as an alternative to combat drug-resistant biofilms which are the prime cause for SSIs.

Extracted chitosan disrupts quorum sensing mediated virulence factors in Urinary tract infection causing pathogens.

Quorum sensing (QS) plays an important role during the aetiology of urinary tract infection (UTI), as several virulence factors are under the regulation of QS. Pseudomonas aeruginosa and Serratia marcescens, the primary causative agents of UTI, employ acyl homoserine lactone (AHL) as signal molecules to coordinate various virulence factors. In this present study, chitosan extracted from the marine crab Portunus sanguinolentus was screened for its ability to inhibit the QS-signaling molecules of P. aeruginosa (PA01) and few clinical isolates of P. aeruginosa and S. marcescens. The extracted chitosan on comparison with a commercial chitosan showed significant inhibition of several QS-dependent virulence factors in P. aeruginosa and S. marscenes. Furthermore, qPCR analysis was carried out to confirm the down-regulation of fimA, fimC and flhD genes involved in adhesion and pathogenesis of S. marcescens and lasI and rhlI genes that governs the P. aeruginosa quorum sensing system. Moreover, the chitosan when coated on a catheter was also able to disrupt the mature biofilms which was revealed by scanning electron microscopy. Collectively, the present study showcases the QS inhibitory property of extracted chitosan from crab shells which is being discarded as a recalcitrant biowaste.