Antibacterial Activity of the Pyrazolone Copper Complex P-FAH-Cu-phen Against Staphylococcus aureus and Promotion of Healing of Traumatized Infected Skin in Mice

<i>Staphylococcus aureus</i> is a major cause of skin and soft tissue infections, necessitating the development of new topical agents with rapid bactericidal activity and low resistance potential. Here, we evaluated the antibacterial activity of a pyrazolone copper complex (P-FAH-Cu-phen) against <i>S. aureus</i>, investigated its in vitro mode of action, and its assessed therapeutic efficacy in a murine model of <i>S. aureus</i>-infected skin trauma. P-FAH-Cu-phen exhibited potent bactericidal activity (minimum inhibitory concentration [MIC] 1.4 μg/mL; minimum bactericidal concentration [MBC] 2.8 μg/mL) and rapid killing (>91% eradication within 2.5 min), with no detectable MIC increase under the tested serial passaging conditions. Cell-envelope dysfunction was evidenced by increased supernatant alkaline phosphatase activity, elevated leakage of nucleic acids and proteins, and reduced membrane-associated Na⁺/K⁺- and Ca²⁺/Mg²⁺-ATPase activities. At sub-inhibitory concentrations, P-FAH-Cu-phen reduced haemolytic and coagulase activities, modulated virulence gene expression (<i>sea</i>, <i>hla</i>, <i>agrA</i>), and inhibited biofilm formation and biofilm-associated metabolic activity. In vivo, topical treatment accelerated wound closure and histopathological repair, increased hydroxyproline content, reduced bacterial burden, and lowered TNF-α and IL-10 levels in wound tissues. Collectively, P-FAH-Cu-phen shows multi-faceted anti-infective activity and exhibits further development as a topical candidate for <i>S. aureus</i>-infected skin wounds.