A New Acid-oxidizing Solution: Assessment of Its Role on Methicillin-resistant Staphylococcus aureus (MRSA) Biofilm Morphological Changes.

Objective. Biofilms represent a key challenge in the treat- ment of chronic wounds, as they are among the main reasons for delays in chronic wound healing. This in vitro study was aimed at evaluating the activity of a new acid-oxidizing solution (AOS) on bio- film formation. Acid-oxidizing solution contains free chlorine spe- cies with stabilized hypochlorous acid in high concentration (> 95%) and is characterized by acidic (pH 1000mV) features. Materials and Methods. A 3-dimensional in vitro model of reconstructed human epidermis was used to compare the activity of AOS vs 2 reference products (RP) containing betaine and polyhexanide (RP1) and sodium hypochlorite and hypochlorous acid (RP2). Different approaches were used to assess the preven- tion and eradication of methicillin-resistant Staphyloccocus aureus biofilm by the study products. Xylitol and chlorhexidine were used as positive controls. The activity of the study products on the biofilm structure was evaluated analyzing the ultrastructural modification by scanning electron microscopy, while skin compatibility was assessed on noncolonized tissues measuring the metabolic activity of the cells. Results. In all experiments, AOS showed to be active on the biofilm matrix, modifying its structure and allowing bacterial release from the matrix. In all experiments, no cytotoxicity was observed in the tissues treated with the product suggesting a good compatibility of AOS with skin tissues. Reference product 1 affected the biofilm, suggesting a disruption effect; RP2 was slightly less active than AOS in modifying the biofilm structure. Conclusion. Treatment with AOS affects biofilm by modifying its structure and therefore facilitating local bacteria accessibility to bactericidal agents, with consequent potential clinical benefits in the treatment of chronic wounds.