A Combination of Blue Light at 460 nm and H₂O₂ for the Safe and Effective Eradication of <i>Staphylococcus aureus</i> in an Infected Mouse Skin Abrasion Model

Antibiotic-free approaches are more important than ever to address the rapidly growing problem of the antibiotic resistance crisis. The photolysis of the bacterial virulence factor staphyloxanthin using blue light at 460 nm (BL460 nm) has been found to effectively attenuate <i>Staphylococcus aureus</i> to chemical and physical agents. However, phototherapy using BL640 nm still needs to be investigated in detail for its safety in eradicating <i>Staphylococcus aureus</i> in vitro and in vivo. In this study, we employed a 460 nm continuous-wavelength LED source and a low concentration of hydrogen peroxide to treat <i>S. aureus</i> under a culturing condition and a wound abrasion mouse model. The results demonstrated the safety of the combined therapy when it did not modify the bacterial virulence factors or the susceptibility to widely used antibiotics. In addition, the results of the mouse model also showed that the combined therapy was safe to apply to mouse skin since it did not cause adverse skin irritation. More importantly, the therapy can aid in healing <i>S. aureus</i>-infected wounds with an efficacy comparable to that of the topical antibiotic Fucidin. The aforementioned findings indicate that the concurrent application of BL460 nm and hydrogen peroxide can be used safely as an alternative or adjunct to antibiotics in treating <i>S. aureus</i>-infected wounds.