Propionibacterium acnes infection as an occult cause of postoperative shoulder pain: a case series.

BACKGROUND Infections after shoulder surgery are potentially devastating complications. Propionibacterium acnes is recognized as a causal agent in shoulder infections. The clinical presentation is usually insidious and nonspecific, but a P. acnes infection could be an occult cause of postoperative shoulder pain. QUESTIONS/PURPOSES What are the clinical and microbiologic characteristics of a postsurgical P. acnes shoulder infection and how should it be addressed? PATIENTS AND METHODS Ten patients with an average age of 57 years presented with P. acnes postsurgical shoulder infection. Clinical infection signs and surgical history were assessed and joint aspirates and tissue biopsy specimens were obtained. Diagnosis was confirmed by microbiologic cultures. RESULTS At the time of confirmation of the diagnosis, clinical signs of infection were absent. C-reactive protein and erythrocyte sedimentation rates were inconsistently elevated. Cultures took a mean 7 days to confirm organism growth. The average time from surgery to diagnosis of infection was 1.8 years (range, 0.07-8.0 years). All patients underwent irrigation and débridement and were treated with antibiotics for 6 weeks. CONCLUSIONS P. acnes shoulder infections should be considered as a cause for persistent, unexplained shoulder pain. Shoulder aspirations and tissue samples should be obtained. Surgical débridement and intravenous antibiotics are necessary treatment modalities. LEVEL OF EVIDENCE Level IV, Prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.