Abstract

Given that the dearth of new antibiotic development loads an existential burden on successful infectious disease therapy1, health organizations are calling for alternative approaches to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we report a drug-free photonic approach to eliminate MRSA through photobleaching of staphyloxanthin, an indispensable membrane-bound antioxidant of S. aureus2-5. The photobleaching process, uncovered through a transient absorption imaging study and quantitated by absorption spectroscopy and mass spectrometry, decomposes staphyloxanthin and sensitizes MRSA to reactive oxygen species attack. Consequently, staphyloxanthin bleaching by low-level blue light eradicates MRSA synergistically with external or internal reactive oxygen species. The effectiveness of this synergistic therapy is validated in MRSA culture, MRSA-infected macrophage cells, S. aureus biofilms, and a mouse wound infection model. Collectively, these findings highlight broad applications of staphyloxanthin photobleaching for treatment of MRSA infections.