Anti-Staphylococcal Biofilm Effects of a Liposome-Based Formulation Containing Citrus Polyphenols

Biofilms are surface-associated microbial communities embedded in a matrix that is almostimpenetrable to antibiotics, thus constituting a critical health threat. Biofilm formation on the cornea orocular devices can lead to serious and difficult-to-treat infections. Nowadays, natural molecules withantimicrobial activity and liposome-based delivery systems are proposed as anti-biofilm candidates.In this study, the anti-biofilm activity of a formulation containing citrus polyphenols encapsulatedin liposomes was evaluated against Staphylococcus aureus and Staphylococcus epidermidis, the mostcommon agents in ocular infections. The formulation activity against planktonic staphylococci wastested by broth microdilution and sub-inhibitory concentrations were used to evaluate the effecton biofilm formation using the crystal violet (CV) assay. The eradicating effect of the preparationon mature biofilms was investigated by the CV assay, plate count, and confocal laser scanningmicroscopy. The product was bactericidal against staphylococci at a dilution of 1:2 or 1:4 and ableto reduce biofilm formation even if diluted at 1:64. The formulation also had the ability to reducethe biomass of mature biofilms without affecting the number of cells, suggesting activity on theextracellular matrix. Overall, our results support the application of the used liposome-encapsulatedpolyphenols as an anti-biofilm strategy to counter biofilm-associated ocular infections.