Topical Benzoyl Peroxide to Reduce Cutibacterium Acnes Load in Shoulder and Spine Surgery: A Randomized Controlled Trial

Introduction & Aim Cutibacterium acnes (C. acnes) is a frequent pathogen in periprosthetic shoulder and surgical spine infections. Numerous strategies aim to reduce cutaneous bacterial load. Recently, studies have advocated using benzoyl peroxide (BPO) to decrease C. acnes colonization in shoulder surgery. This study determined if preoperative topical BPO application reduces C. acnes culture positivity incidence following primary shoulder and spine surgery in a large patient cohort. Methods This single-center prospective randomized trial included patients undergoing primary reverse shoulder arthroplasty for cuff-deficient shoulders (shoulder cohort) or instrumented and non-instrumented primary lumbar surgeries (spine cohort). Participants were randomized to apply daily topical BPO cream starting 72 hours before surgery (BPO group) or to a control group receiving no topical BPO. Intraoperatively, eight cultures were obtained per patient: two from the skin following incision and six from deeper tissue layers. The microbiologist remained blinded to group assignments. Recorded variables included age, gender, culture results, and any topical adverse reactions. All included patients completed a minimum clinical follow-up of 12 months. Results 199 patients (102 spine; 97 shoulder) were included, comprising 134 females and 65 males, with a mean age of 68.09 years (SD 13.38). There were 47 patients in the shoulder BPO group (48.5%) and 46 in the spine BPO group (45.1%). C. acnes was cultured in 45 patients (22.61%): 27 in the non-BPO group and 18 in the BPO group (p = 0.303). Within the shoulder cohort (80 females, 17 males; mean age 74.82, SD 7.61), 17 patients had positive C. acnes cultures (17.5%), with 10 in the non-BPO group and 7 in the BPO group (p=0.509); no postoperative infections occurred. Within the spine cohort (54 females, 48 males; mean age 61.31, SD 14.65), 28 patients had positive cultures (27.45%), including 17 in the non-BPO group and 11 in the BPO group (p=0.684). Four postoperative infections occurred in the spine cohort (1 non-BPO; 3 BPO; p=0.205). No adverse effects from BPO use were reported. Conclusions Preoperative topical application of BPO did not significantly reduce the rate of positive C. acnes cultures in either the shoulder or spine cohorts in this prospective randomized trial. At one-year follow-up, BPO application did not lead to a reduction in postoperative infection rates within the spine cohort. These results indicate that preoperative BPO application may not provide additional clinical benefit in reducing C. acnes colonization or subsequent surgical site infection.