Characterization of Blue Light Treatment for Infected Wounds: Antibacterial Efficacy of 420, 455, and 480 nm
Isabell Plattfaut1, Erhan Demir2, Paul C Fuchs2
1Chair, Department of Virology and Microbiology, Centre for Biomedical Education and Research (ZBAF), University Witten/Herdecke, Witten, Germany.
Abstract:
To determine effective treatment strategies against bacterial infections of chronic wounds, we tested different blue light (BL)-emitting light-emitting diode arrays (420, 455, and 480 nm) against wound pathogens and investigated in parallel BL-induced toxic effects on human dermal fibroblasts. Wound infection is a major factor for delayed healing. Infections with Pseudomonas aeruginosa and Staphylococcus aureus are clinically relevant caused by their ability of biofilm formation and their quickly growing antibiotics resistance. BL has demonstrated antimicrobial properties against various microbes. Determination of antibacterial and cell toxic effects by colony-forming units (CFUs)/biofilm/cell viability assays, and live cell imaging. A single BL irradiation (180 J/cm2), of P. aeruginosa at both 420 and 455 nm resulted in a bacterial reduction (>5 log10 CFU), whereas 480 nm revealed subantimicrobial effects (2 log10). All tested wavelengths of BL also revealed bacteria reducing effects on Staphylococcus epidermidis and Escherichia coli (maximum 1-2 log10 CFU) but not on S. aureus. Dealing with biofilms, all wavelengths using 180 J/cm2 were able to reduce significantly the number of P. aeruginosa, E. coli, and S. epidermidis. Here, BL420nm achieved reductions up to 99%, whereas BL455nm and BL480nm were less effective (60-83%). Biofilm-growing S. aureus was more BL sensitive than in the planktonic phase showing a reduction by 63-75%. A significant number of cell toxic events (>40%) could be found after applying doses (>30 J/cm2) of BL420nm. BL455nm showed only slight cell toxicity (180 J/cm2), whereas BL480nm was nontoxic at any dose. BL treatment can be effective against bacterial infections of chronic wounds. Nevertheless, using longer wavelengths >455 nm should be preferred to avoid possible toxic effects on skin and skin cells. To establish BL therapy for infected chronic wounds, further studies concerning biofilm formation and tissue compatibility are necessary.
Insights
Blue light (BL) therapy shows promise for treating chronic wound infections caused by bacteria like Pseudomonas aeruginosa and Staphylococcus aureus. Wavelengths longer than 455 nm are recommended to minimize potential skin cell toxicity.
Area of Science:
- Photomedicine
- Antimicrobial Therapy
- Wound Healing Research
Background:
- Chronic wound infections impede healing and are often caused by antibiotic-resistant bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus.
- Blue light (BL) exhibits antimicrobial properties, making it a potential therapeutic agent for wound infections.
Purpose of the Study:
- To evaluate the efficacy of different blue light (BL)-emitting diode wavelengths (420, 455, and 480 nm) against key wound pathogens.
- To assess the potential toxic effects of BL irradiation on human dermal fibroblasts.
Main Methods:
- Bacterial reduction was quantified using colony-forming units (CFUs) and biofilm assays.
- Cell viability and toxic effects were determined through live cell imaging and specific assays.
- Different blue light wavelengths (420, 455, 480 nm) were applied at a standard dose (180 J/cm²).
Main Results:
- BL at 420 and 455 nm significantly reduced Pseudomonas aeruginosa (>5 log10 CFU), while 480 nm showed subantimicrobial effects (2 log10).
- Blue light effectively reduced biofilms of P. aeruginosa, E. coli, and S. epidermidis, with 420 nm showing the highest efficacy (up to 99%).
- Higher BL doses (>30 J/cm²) of 420 nm induced significant toxicity (>40%) in dermal fibroblasts, whereas 455 nm showed slight toxicity and 480 nm was non-toxic.
Conclusions:
- Blue light treatment can be effective against bacterial infections in chronic wounds.
- Longer BL wavelengths (>455 nm) are preferable to mitigate potential toxicity to skin and dermal cells.
- Further research on biofilm dynamics and tissue compatibility is essential for establishing BL therapy for infected chronic wounds.
