Photodynamic therapy for Cutibacterium acnes decolonization of the shoulder dermis

Introduction: Cutibacterium acnes (C. acnes) is a common source of infection in shoulder surgery. 5-Aminolevulinic acid (5-ALA) is a naturally occurring metabolite of C. acnes that creates an exothermic reaction when activated by blue light. The purpose of this study was to evaluate the efficacy of preoperative photodynamic therapy using topical 5-ALA to decrease C. acnes colonization. Methods; Patients were randomized to receive topical 5-ALA skin solution activated by blue light photodynamic therapy or standard of care preoperative skin preparation. Prior to skin incision, two punch biopsy specimens were taken from the portal sites and were incubated for 13 days. Culture positivity rate, days until positive, and semiquantitative growth classification were analyzed. Results: Fifty patients undergoing arthroscopic shoulder surgery were randomized. The overall positive culture rate was 54%. All cultures were positive for C. acnes except for one. Sixty-four percent of standard preparation patients and 44% of investigational group patients had at least one positive culture for C. acnes. There was no significant difference between groups in patients with at least one positive C. acnes culture (p = 0.49). Conclusion: The use of photodynamic therapy undergoing arthroscopic shoulder surgery did not significantly reduce colonization of C. acnes as compared to standard preparation.