Vitreoscilla filiformis Supernatant: A Novel Postbiotic Secretome for the Prevention and Treatment of Wound Infections.

Background: Biofilms consist of complex microbial communities embedded in an extracellular matrix which confer resistance to the most used antimicrobial agents. Chronic wounds are often associated with burns, trauma, surgery, diabetes and peripheral vascular disease. They are characterized by a marked delay in wound healing favoring the development of microbial biofilms, which in turn further delay tissue regeneration. Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant staphylococci biofilms are found in chronic wounds, seriously hindering wound treatment. Vitreoscilla filiformis, a Gram-negative non-pathogenic filamentous bacterium, has been shown to improve atopic dermatitis by reducing S. aureus colonization and inducing antioxidant responses in the skin. Objectives: The aim of the present study was to evaluate the antimicrobial, anti-inflammatory, and regenerative activities of the V. filiformis supernatant (VFS). Methods: The effect of VFS on bacteria growth was assessed by microbial growth kinetics and biofilm formation and dispersal. Antioxidant potential was determined by DPPH-scavenging ability and reduction in intracellular reactive oxygen species (ROS). The regenerative properties were assessed by scratch assay. Results: V. filiformis VFS holds strong anti-biofilm activity against S. aureus, S. epidermidis and methicillin-resistant S. aureus (MRSA), acting during both biofilm formation and dispersion. The decrease in biofilm mass is accompanied by a significant increase in the planktonic form compared to the untreated cells. Moreover, VFS is characterized by an interesting antioxidant activity, as demonstrated by a cell-free DPPH assay and a neutrophil-based in vitro assay. In addition, VFS can stimulate tissue regeneration in human dermal fibroblasts and keratinocytes. Conclusions: The demonstration of anti-biofilm, antioxidant and regenerative properties of V. filiformis supernatant could be exploited for the treatment of biofilm-associated wound infections.