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Antimicrobial Blue Light

The use of blue light, mainly in the wavelength rage of 400-470nm, is a potential solution to SSIs due to its proven antimicrobial effects, specifically for inactivating wound pathogens, and for its ability to improve wound healing[8-10]. Blue light is intrinsically antimicrobial, and can photodynamically inactivate a wide spectrum of bacteria, both gram-positive and negative, and fungi[9]. Additionally, blue light is equally effective against drug sensitive and resistant bacteria, less detrimental to mammalian cells than UV radiation, and bacteria do not develop a resistance to blue light therapy[11]. The mechanism of blue light’s antimicrobial effect is similar to photodynamic therapy (PDT), however, no exogenous photosensitizer is required for blue light therapy[9]. Blue light bacterial inactivation occurs due to the photo- excitation of intracellular porphyrins, resulting in production of cytotoxic reactive oxygen species (ROS), such as oxygen radicals, singlet oxygen and peroxides[11, 12]. When the endogenous photosensitizer is transformed to an excited state it will undergo a type I or type II photochemical reaction forming hydroxyl radicals or singlet oxygen, respectively[13]. The excitation of endogenous porphyrins generates an abundance of ROS which overwhelm the bacterial cell’s antioxidant capacity causing damage to proteins, enzymes, lipids, and DNA, resulting in bacterial cell death and inactivation of virulence factors [12-14]. Blue light is an ideal technology for use on the human body for infection prevention because it can excite endogenous porphyrins in bacterial cells, such as MRSA, that are not present in host cells, allowing for bacteria to be selectively inactivated while host tissue cells are preserved, preventing harm to mammalian host cells[12, 15].

Blue light antimicrobial therapy is FDA approved and currently being utilized clinically for treatment Propionibacterium acnes, environmental decontamination of hospital rooms, and has significant potential to be utilized for wound management and infection prevention. Multiple blue light therapy studies, both in vivo and in vitro , have been performed showing that blue light therapy successfully inactivates Staphylococcus aureus, MRSA, Clostridium difficile, Acinetobacter baumanni, Escherichia coli, S. epidermidis, Pseudomonas aeruginosa, Klegsiella

pneumoniae, Streptococcus pyogenes, Mycobacterium spp., Propionibacterium acnes, and Helicobacter pylori [11, 16-18]. Dai et al. performed studies with mice, infecting them with Pseudomonas aeruginosa on burns and applying blue light for antimicrobial therapy showing that blue light therapy of localized infections can prevent mice from dying from systemic infections. Blue light therapy increased the survival rate of the infected mice from 18.2% to 100%[8]. Animal studies and bench-top studies with blue light at similar dosages has shown to not impair wound healing, and even induce angiogenesis[19, 20]. A study on wound healing in an excision model in rats by Adamskaya et al. showed that blue light significantly influences wound healing, and could provide an easily applicable safe and cost-effective treatment of surface wounds[10].


  1. CDC, Surgical Site Infection (SSI) Event, C.f.D. Control, Editor. 2017.

  2. Cheadle, W.G., Risk factors for surgical site infection. Surgical infections, 2006. 7(S1): p. s7-s11.


  4. Urban, J.A., Cost analysis of surgical site infections. Surgical infections, 2006. 7(S1): p. s19-s22.

  5. Schweizer, M.L., et al., Costs associated with surgical site infections in veterans affairs hospitals. JAMA surgery, 2014. 149(6): p. 575-581.

  6. Owens, C. and K. Stoessel, Surgical site infections: epidemiology, microbiology and prevention. Journal of Hospital Infection, 2008. 70: p. 3-10.

  7. Høiby, N., et al., ESCMID guideline for the diagnosis and treatment of biofilm infections 2014. Clinical microbiology and infection, 2015. 21: p. S1-S25.

  8. Dai, T., et al., Blue light rescues mice from potentially fatal Pseudomonas aeruginosa burn infection: efficacy, safety, and mechanism of action. Antimicrobial agents and chemotherapy, 2013. 57(3): p. 1238-1245.

  9. Dai, T., et al., Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond? Drug Resist Updat, 2012. 15(4): p. 223-36.

  10. Adamskaya, N., et al., Light therapy by blue LED improves wound healing in an excision model in rats. Injury, 2011. 42(9): p. 917-921.

  11. Halstead, F.D., et al., Antibacterial Activity of Blue Light against Nosocomial Wound Pathogens Growing Planktonically and as Mature Biofilms. Appl Environ Microbiol, 2016. 82(13): p. 4006-16.

  12. Agrawal,T.,etal.,Harnessingthepoweroflighttotreatstaphylococcal infections focusing on mrsa. Current pharmaceutical design, 2015. 21(16): p. 2109-2121.

  13. Thannickal, V.J. and B.L. Fanburg, Reactive oxygen species in cell signaling. American Journal of Physiology-Lung Cellular and Molecular Physiology, 2000. 279(6): p. L1005-L1028.

  14. Ashkenazi, H., et al., Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light. FEMS Immunology & Medical Microbiology, 2003. 35(1): p. 17-24.

  15. Dai, T., et al., Blue Light Eliminates Community-Acquired Methicillin- Resistant Staphylococcus aureus in Infected Mouse Skin Abrasions. Photomedicine and Laser Surgery, 2013. 31(11): p. 531-538.

  16. Enwemeka, C.S., et al., Visible 405 nm SLD light photo-destroys methicillin-resistant Staphylococcus aureus (MRSA) in vitro. Lasers Surg Med, 2008. 40(10): p. 734-7.

  17. Maclean, M., et al., Inactivation of bacterial pathogens following exposure to light from a 405-nanometer light-emitting diode array. Appl Environ Microbiol, 2009. 75(7): p. 1932-7.

  18. Murdoch, L.E., et al., Bactericidal Effects of 405 nm Light Exposure Demonstrated by Inactivation of Escherichia, Salmonella, Shigella, Listeria, and Mycobacterium Species in Liquid Suspensions and on Exposed Surfaces. The Scientific World Journal, 2012. 2012: p. 137805.

  19. Masson-Meyers, D.S., V .V . Bumah, and C.S. Enwemeka, Blue light does not impair wound healing in vitro. Journal of Photochemistry and Photobiology B: Biology, 2016. 160: p. 53-60.

  20. Dungel, P., et al., Low level light therapy by LED of different wavelength induces angiogenesis and improves ischemic wound healing. Lasers in surgery and medicine, 2014. 46(10): p. 773-780.