Propionibacterium acnes (“P Acnes”) is a gram-positive anaerobic bacillus closely associated with sebum-rich hair follicles.
Recently, a growing body of literature has demonstrated it as also a common pathogen in shoulder infections.
It is recognized as the most frequent agent causing postoperative septic arthritis in the shoulder, comprising 56% of shoulder infections. Some studies have shown presence of P acnes in up to 16% of infected primary shoulder replacements and up to 21% of revision shoulder arthroplasties. It has also been found to be the most frequent agent isolated from rotator cuff surgery infections. A 2014 study by Levy et al reported 42% of patients with shoulder arthritis undergoing primary shoulder arthroplasty had presence of P Acnes in the glenohumeral joint, proposing it may be the cause of or contributing factor to development of the disease.