Targeting Intracellular MRSA: Ga³⁺CHP-Mediated Antimicrobial Photodynamic Inactivation as a Promising Therapeutic Strategy

Recurrent skin infections pose a significant challenge in dermatological treatment, with approximately 50% of Staphylococcus aureus-infected patients experiencing reinfection within six months post-therapy. This is largely attributed to the intracellular persistence of bacteria within keratinocytes, the predominant cells of the epidermis, which shield the pathogens from immune cells and antibiotics, most of which fail to penetrate eukaryotic cells effectively. We optimized a human keratinocyte infection model using S. aureus to investigate intracellular persistence and evaluate therapeutic strategy based on photodynamic approach. The study demonstrated that photodynamic therapy employing a porphyrin derivative and green light effectively targeted intracellular S. aureus. Photodynamic therapy with a porphyrin-based photosensitizer and green light represents an effective method to eliminate intracellular S. aureus, offering a promising alternative approach for managing recurrent skin infections.