Burn wound infections remain a major source of morbidity in patients with thermal injuries and contribute to delayed healing, graft loss, and prolonged hospitalization. The emergence of antimicrobial-resistant organisms further complicates management and highlights the need for non-antibiotic antimicrobial strategies. Photodynamic therapy (PDT) is an antimicrobial approach that combines a photosensitizing agent with visible light to generate reactive oxygen species capable of killing bacteria.

This randomized clinical trial will evaluate the safety and preliminary efficacy of methylene blue-mediated photodynamic therapy for the treatment of burn wound bacterial contamination. Participants receiving standard burn care will be randomized to receive either methylene blue-photodynamic therapy with blue light illumination or light therapy alone during routine dressing changes. Treatments will occur during two consecutive dressing changes. The primary objective is to determine whether methylene blue photodynamic therapy reduces bacterial burden in burn wounds compared with light therapy alone. Secondary outcomes include safety, tolerability, and effects on wound healing.

Burn wound infections remain a major complication following thermal injury and contribute to delayed wound healing, graft failure, prolonged hospitalization, and increased healthcare utilization. Management of burn wound bacterial contamination relies heavily on topical and systemic antibiotics. However, the increasing prevalence of antimicrobial-resistant organisms has created a need for alternative antimicrobial strategies that do not rely on conventional antibiotics. Photodynamic therapy (PDT) is a non-antibiotic antimicrobial approach that combines a photosensitizing compound with visible light to generate reactive oxygen species that rapidly kill bacteria through oxidative damage.

Methylene blue is a well-characterized photosensitizer with known antimicrobial activity when activated by visible light. When exposed to appropriate wavelengths of light, methylene blue produces singlet oxygen and other reactive oxygen species that disrupt bacterial cell membranes and intracellular components. Photodynamic therapy has demonstrated broad antimicrobial activity in laboratory and preclinical studies, including activity against antibiotic-resistant organisms. The use of PDT for treatment of contaminated wounds offers the potential to reduce bacterial burden while minimizing the risk of antimicrobial resistance.

This study is a randomized clinical trial designed to evaluate the safety and preliminary antimicrobial efficacy of methylene blue-mediated photodynamic therapy in burn wounds. Participants receiving standard burn care will be randomized to receive either methylene blue photodynamic therapy with blue light illumination or light therapy alone during routine dressing changes. Treatments will occur during two consecutive dressing changes. Methylene blue will be applied to the burn wound surface prior to illumination with a blue light source.

The primary objective of this study is to determine whether methylene blue photodynamic therapy reduces bacterial burden in burn wounds compared with light therapy alone. Secondary objectives include evaluation of treatment safety, tolerability, and effects on wound healing. Results from this study will inform the feasibility and design of future trials evaluating photodynamic therapy as a novel adjunctive treatment for burn wound infection.

Inclusion

• Age ≥18
• Partial- or full-thickness burn with partial-thickness component
• Expected ≥7 days dressing changes
• Able to consent

Exclusion

• Pregnancy or lactation

  o Pregnancy status will be determined by review of the medical record and, when clinically indicated per institutional policy, standard-of-care pregnancy testing. No additional pregnancy testing will be performed solely for research purposes.

• Current use of SSRIs, SNRIs, MAO inhibitors, and other serotonergic agents

• Inability to tolerate wound exposure

• Inability to consent

• Known glucose-6-phosphate dehydrogenase (G6PD) deficiency

Individual participant data will not be shared. De-identified aggregate study results may be reported in scientific publications and presentations.

Due to the visible application of methylene blue during photodynamic therapy, blinding of participants and treating clinicians is not feasible. Outcome measures include quantitative bacterial cultures obtained from burn wounds.