Benzoyl peroxide combined with subcutaneous iodine reduces Cutibacterium acnes presence during shoulder surgery : a three-armed, single-blinded, randomized controlled trial.

Aims: The purpose of this study was to assess the effect of combined preoperative benzoyl peroxide application and subcutaneous povidone-iodine (PV-I) disinfection, in addition to standard PV-I disinfection of the skin, on intraoperative cultures of Methods: All patients undergoing arthroscopic or open shoulder surgery were eligible for inclusion. Patients were randomized into one of three groups: control (standard disinfection of the skin with PV-I), double prevention (disinfection of the skin and subcutaneous tissue with PV-I after incision for 60 seconds), and triple prevention (application of benzoyl peroxide during the three days before surgery, disinfection of the skin with PV-I, and disinfection of the subcutaneous tissue with PV-I after incision for 60 seconds). Cultures were taken of the tissue layers, equipment, and the surgeon's gloves. A sample size of 156 patients was calculated. Culture positivity was compared between the groups, with the intra-articular and deep muscular culture as the primary outcome. Results: A total of 156 patients (median age 58 years (IQR 20 to 85), with 61 patients (39%) being female) were included. The intra-articular cultures were positive in 16 patients (32%) in the control group, 11 (21%) in the double prevention group, and five (10%) in the triple prevention group (p = 0.031). Conclusion: Combining disinfection of the subcutaneous tissue after incision with preoperative application of benzoyl peroxide reduced the presence of