Search

Chronic wound infections represent an important health problem due to the reduced response to antimicrobial treatment of the pathogens organized in structured biofilms. This study investigated the effects of the previously described antifungal peptide L18R against three representative wound pathogens: Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The antimicrobial activity of L18R was evaluated (i) against single planktonic microbial populations; (ii) on single, dual, and triadic species of biofilms in both the early stage and mature stage; and (iii) in the polymicrobial Lubbock chronic wound biofilm (LCWB) model, mimicking spatial microbial colonization. This study used the evaluation of CFUs, biofilm biomass detection, and confocal and scanning electron microscopy analysis. L18R showed a significant antimicrobial activity against planktonic microorganisms and was able to differentially reduce the biomass of monomicrobial biofilms. No reduction of biomass was observed against the polymicrobial biofilm. In mature LCWB, L18R caused a moderate reduction in total CFU number, with a variable effect on the different microorganisms. Microscopy images confirmed a predominant presence of P.aeruginosa and a lower percentage of C. albicans cells. These findings suggest a modulating action of L18R and recommend further studies on its potential role in chronic wound management in association with conventional antibiotics or alternative treatments.

Background: An unbalanced skin microbiota due to an increase in pathogenic vs. commensal bacteria can be efficiently tackled by using prebiotics. The aim of this work was to identify novel prebiotic combinations by exerting species-specific action between S. aureus and S. epidermidis strains. Methods: First, the antimicrobial/antibiofilm effect of Xylitol-XYL and Galacto-OligoSaccharides–GOS combined with each other at different concentrations (1, 2.5, 5%) against S. aureus and S. epidermidis clinical strains was evaluated in time. Second, the most species-specific concentration was used to combine XYL with Fructo-OligoSaccharides–FOS, IsoMalto-Oligosaccharides–IMO, ArabinoGaLactan–LAG, inulin, dextran. Experiments were performed by OD600 detection, biomass quantification and LIVE/DEAD staining. Results: 1% XYL + 1% GOS showed the best species-specific action with an immediate antibacterial/antibiofilm action against S. aureus strains (up to 34.54% ± 5.35/64.68% ± 4.77) without a relevant effect on S. epidermidis. Among the other prebiotic formulations, 1% XYL plus 1% FOS (up to 49.17% ± 21.46/37.59% ± 6.34) or 1% IMO (up to 41.28% ± 4.88/36.70% ± 10.03) or 1% LAG (up to 38.21% ± 5.31/83.06% ± 5.11) showed antimicrobial/antibiofilm effects similar to 1% XYL+1% GOS. For all tested formulations, a prevalent bacteriostatic effect in the planktonic phase and a general reduction of S. aureus biofilm formation without loss of viability were recorded. Conclusion: The combinations of 1% XYL with 1% GOS or 1% FOS or 1% IMO or 1% LAG may help to control the balance of skin microbiota, representing good candidates for topic formulations.