What question did this study set out to answer?

To evaluate the effect of preoperative topical 5% benzoyl peroxide on deep C. acnes contamination during shoulder arthroscopy.

June 26, 2026Open Access

Preoperative topical 5% benzoyl peroxide reduces intraoperative deep cutibacterium acnes contamination in shoulder arthroscopy: a retrospective cohort study

Key Points

To evaluate the effect of preoperative topical 5% benzoyl peroxide on deep C. acnes contamination during shoulder arthroscopy.
Retrospective cohort analysis of 162 patients undergoing shoulder arthroscopy, divided into BPO pretreatment and control groups.
Deep specimens obtained for anaerobic culture to measure contamination rates and skin colonization.
Utilized multivariable logistic regression, Poisson regression, and non-parametric tests for statistical analysis.
BPO group had a lower deep contamination rate (16.05% vs. 34.57%; RR = 0.46, 95%CI 0.26-0.83, p = 0.007).
Adjusted odds ratio for deep contamination was 0.38 (95%CI 0.18-0.79).
Preoperative skin colonization load was significantly lower in the BPO group (p = 0.001).

Abstract

BACKGROUND: Intraoperative deep contamination with Cutibacterium acnes (C. acnes) from hair follicles and sebaceous glands remains a microbiological risk in shoulder arthroscopy, and routine chlorhexidine-alcohol skin preparation has limited efficacy against this reservoir. OBJECTIVE: To evaluate the association between preoperative topical 5% benzoyl peroxide use and intraoperative deep C. acnes contamination, and to explore skin colonization load. METHODS: A retrospective cohort analysis was performed on patients undergoing shoulder arthroscopy. Deep specimens (synovial fluid, synovium, inner portal cannula wall) were obtained for anaerobic culture. The primary outcome was the patient-level deep contamination rate. Relative risks (RR), adjusted odds ratios (aOR), and incidence rate ratios (IRR) were estimated using multivariable logistic regression, Poisson regression, and non-parametric tests. Sensitivity analyses used a strict positivity definition. RESULTS: The cohort included 162 patients (81 with BPO pretreatment, 81 with standard preparation alone). The BPO group had a lower deep contamination rate (16.05% vs. 34.57%; RR = 0.46, 95%CI 0.26-0.83, p = 0.007), with an adjusted aOR = 0.38 (95%CI 0.18-0.79). The number of positive deep specimens per patient was lower (IRR = 0.44, p = 0.004). Among positive cases, the time to culture positivity was delayed in the BPO group (p = 0.031). Preoperative skin colonization load was lower in the BPO group (p = 0.001). A higher skin score was independently associated with increased risk of deep contamination (aOR = 1.57 per 1-grade increase, 95%CI 1.19-2.07, p = 0.002). Sensitivity analyses showed consistent results. No significant between-group differences were found in short-term infection-related clinical events. CONCLUSION: In this retrospective analysis, preoperative topical 5% benzoyl peroxide was associated with a significant reduction in intraoperative deep C. acnes contamination and bacterial burden during shoulder arthroscopy, supporting the microbiological rationale for a source decolonization strategy. CLINICAL TRIAL REGISTRATION: Not applicable.

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