High-Intensity Blue Light (450-460 nm) Phototherapy for Pseudomonas aeruginosa-Infected Wounds.

Background: Nosocomial wound infection with Pseudomonas aeruginosa (PA) is a serious complication often responsible for the septic mortality of burn patients. Objective: High-intensity antimicrobial blue light (aBL) treatment may represent an alternative therapy for PA infections and will be investigated in this study. Methods: Antibacterial effects of a light-emitting diode array (450-460 nm; 300 mW/cm²; 15/30 min; 270/540 J/cm²) against PA were determined by suspension assay, biofilm assay, and a human skin wound model and compared with 15-min topically applied 3% citric acid (CA) and wound irrigation solution (Prontosan^®; PRT). Results: aBL reduced the bacterial number [2.51-3.56 log₁₀ colony-forming unit (CFU)/mL], whereas PRT or CA treatment achieved a 4.64 or 6.60 log₁₀ CFU/mL reduction in suspension assays. aBL reduced biofilm formation by 60-66%. PRT or CA treatment showed reductions by 25% or 13%. Here, aBL reduced bacterial number in biofilms (1.30-1.64 log₁₀ CFU), but to a lower extend than PRT (2.41 log₁₀ CFU) or CA (2.48 log₁₀ CFU). In the wound skin model, aBL (2.21-2.33 log₁₀ CFU) showed a bacterial reduction of the same magnitude as PRT (2.26 log₁₀ CFU) and CA (2.30 log₁₀ CFU). Conclusions: aBL showed a significant antibacterial efficacy against PA and biofilm formation in a short time. However, a clinical application of aBL in wound therapy requires effective active skin cooling and eye protection, which in turn may limit clinical implementation.