NOVEL BIOACTIVE GLASS S53P4 CREAM AND ITS ELUATE: A PROMISING STRATEGY AGAINST STAPHYLOCOCCUS AUREUS BIOFILM AND BONE INFECTION

Orthopedic implant-associated infections (OIAIs), predominantly caused by Staphylococcus aureus , pose significant challenges due to biofilm formation and antibiotic resistance, leading to persistent and recurrent infections. Bioactive Glass (BAG) S53P4 is a unique material with antimicrobial and bone regenerative properties. A novel BAG cream formulation can be used as an advanced coating solution to prevent or treat OIAIs. Aim In this study we aimed to characterize a novel BAG S53P4 cream, consisting of antimicrobial BAG powder and binder, for its bactericidal and biofilm killing activity in vitro and efficacy in a cadaver mouse bone infection model. Since the bactericidal effects is dependent on eluted compounds, we analysed the bactericidal activity of BAG cream, BAG powder, binder and their eluates against S. aureus. Method To study the influence of the elution time, S. aureus was exposed to eluates collected at 2, 4, 8, and/or 24 hours. The bactericidal and biofilm-killing activity were quantitatively analysed. A time kill assay was performed to assess the speed of killing of S. aureus . The pH was measured to study its relevance for the bactericidal action of BAG. In a cadaver mouse bone infection model, BAG cream was applied to an S. aureus infected femoral bone defect. Results The BAG cream, BAG powder and their eluates eradicated planktonic S. aureus and significant killing of S. aureus biofilms was observed with the cream and powder eluates. All eluates, including the eluate collected at the earliest elution time of 2 hours, were highly effective against S. aureus , indicating rapid release of bactericidal activity from BAG cream and powder. Time-kill experiments revealed rapid bactericidal activity of BAG cream and powder eluates, with killing starting as early as 30 minutes and increasing with longer exposure times. BAG cream applied to an S. aureus cadaver mouse bone infection model inhibited bacterial growth effectively. Conclusion These findings show the potential of BAG cream as an innovative solution for managing OIAIs. As a next step we intend to investigate the in vivo antibacterial efficacy and safety of BAG cream applied in a mouse bone fixation plate infection model.