Low‐level blue light therapy shows promise for the treatment of acne vulgaris, according to a poster presented at the 2019 American Academy of Dermatology Annual Meeting in Washington, DC.
Researchers from Rutgers University and Johnson and Johnson investigated the effect of sub-milliwatt/cm2 levels of blue light on Propionibacterium acnes, a type of bacterium that produces high levels of light-sensitive porphyrins.
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“Photoexcitation of porphyrins by blue light may generate intracellular reactive oxygen species, which ultimately lead to cell death,” investigators explained in the poster. They added that the mode of action would likely be selective because few other bacteria generate high porphyrin levels.
The study investigated the effect of blue light sources with peak wavelengths of 449 nanometers (nm) on cell cultures and controls in liquid and solid media.
In both liquid and solid cultures, exposing P acnes to 449 nm of light resulted in bacterial cell death, researchers reported. The antibacterial effect was dependent on time of exposure, light intensity, and environmental oxygen. Even in antibiotic-resistant strains of P acnes, blue light demonstrated antimicrobial activity.
“The work presented demonstrates the antimicrobial activity of 449 nm blue light against P acnes—a causative agent of acne vulgaris,” researchers concluded. “Collectively, the findings presented suggest that low‐level light therapy using 440 nm blue light may provide an effective and safe treatment for acne vulgaris.”
Boyd J, Dunn K, Fassih A, et al. Antibacterial effect of low-level blue light on Propionibacterium acnes and antibiotic resistant P. acnes. Presented at: the American Academy of Dermatology Annual Meeting; Washington, DC; March 1-5, 2019.