A Comparison of White-light and Monochromatic LED Sources for Antimicrobial Photodynamic Inactivation of Staphylococcus aureus

Drug-resistant bacteria are an ongoing public health crisis for which alternative treatments are needed. One alternative is antimicrobial photodynamic inactivation (aPDI), which uses potent photosensitizers and light irradiation to damage the bacteria. Our standard light source used in aPDI is a single-wavelength light source at 405-nm; however, we evaluated a white-light source for similarities in the resulting aPDI activities. This is done by comparing aPDI experiments using S. aureus and its methicillin-resistant strains (MRSA) conducted with either the white LED light source or the 405-nm LED light source. Statistical analysis using t-tests revealed no significant differences in the aPDI activities between the white LED light source and the 405-nm LED light source. This indicated that the white-light source can be just as effective as the 405-nm light. The white light is easier to use, as well as being widely available and much less expensive. It can also be used on any surface, which would be especially useful when applied to decontamination of surfaces.