The Incidence of Propionibacterium acnes in Shoulder Arthroscopy

Purpose To document the skin colonization and deep tissue inoculation rates associated with arthroscopic shoulder surgery and how these rates differ with procedural and demographic factors. Methods We prospectively recruited outpatient shoulder arthroscopy patients who agreed to participate and met the inclusion criteria from February 2013 to May 2014. All patients received routine antibiotic prophylaxis intravenously. Initial cultures were obtained before the skin preparation by swabbing the skin at the 3 standard portal sites: posterior, anterosuperior, and anterolateral. The skin preparation used 4% chlorhexidine scrub and 2% chlorhexidine gluconate/70% isopropyl alcohol paint applied to the entire shoulder. After completion of the arthroscopic procedure, a second culture was obtained through a cannula at the surgical site. All cultures were plated for 21 days using Brucella medium. Results We enrolled 51 patients over a 15-month period. Cultures showed a 72.5% Propionibacterium acnes superficial colonization rate: 46.1% of female and 81.6% of male patients ( P = .027). We identified a deep culture–positive inoculation rate of 19.6%, all with positive P acnes skin colonization. No correlation could be made concerning diagnosis, procedure, suture anchor use, age, or sex. Conclusions The rate of skin colonization with P acnes is high at arthroscopic portals, especially in men. Despite standard skin preparation and prophylactic antibiotics, the rate of deep tissue inoculation with P acnes in shoulder arthroscopy is much higher than the rate of infection reported in the literature. Clinical Relevance Shoulder arthroscopy introduces a significant amount of P acnes into the deep tissues.