Effect of a white grape (Vitisvinifera L.) juice extract on the growth and biofilm production of methicillin-resistant and sensitive Staphylococcus species

Background: The aim of the present study was to evaluate the antibacterial effect of a white grape juice extract (WGJe) against Staphylococcus species. WGJe was also tested on the production of bacterial biofilms in vitro. Methods and Results: The minimum inhibitory concentration (MIC) of WGJe against the tested strains was determined by the broth microdilution method, according to CLSI. WGJe was effective against S. aureus and S. epidermidis, both ATCC and clinical isolates, with S. aureus being more sensitive than S. epidermidis. The effect was bactericidal at concentrations of 500 μg/ml for S. aureus, and 2000 μg/ml for S. epidermidis. Biofilm production was determined following previously published methods. WGJe inhibited biofilm formation of S. aureus and S. epidermidis in a dose-dependent manner. Conclusions: These results could be used to develop novel strategies for the treatment of skin infection and the production of topical formulations. WGJs could also be used in combination with antibiotics to help eradicate pre-established biofilms.