Discussion:
   - see anaerobic joint infections
   - slow growing, typically aerotolerant anaerobic gram positive bacterium;
   - found in skin pores and the gut.
   - may colonize the axilla (esp in males)
   - positive cultures may be seen patients having revision shoulder arthroplasty performed for pain, stiffness, and component loosening
   - main clinical findings may be unexplained pain, stiffness, or component loosening months to years after the index arthroplasty.
   - note difficulty in obtaining positive cultures from standard lab cultures;
   - see A Microbial Biorealm page on the genus Propionibacterium and Propionibacterium Infections for e-Medicine
   
   - may be most common cause of rotator cuff infections;
          - references:
                 - Deep Infection after Rotator Cuff Repair.
                 - Infection after mini-open rotator cuff repair. 
                 - Propionibacterium acnes colonization of the human shoulder.
                 - Positive Culture Rate in Revision Shoulder Arthroplasty
                 - Propionobacter acnes Infection as an Occult Cause of Postoperative Shoulder Pain: A Case Series

   - total joint infection:
          - references:
                 - Propionibacterium acnes: an agent of prosthetic joint infection and colonization.
                 - Microbiologic diagnosis of prosthetic shoulder infection by use of implant sonication.
                 - Species of Propionibacterium and Propionibacterium acnes types associated with orthopedic implants
                 - Propionibacterium spp. in prosthetic joint infections: a diagnostic challenge
                 - Late anaerobic haematogenous infection of total joint replacement. A study in the rabbit using Propionibacterium acnes.
                 - Propionibacterium acnes infection after shoulder arthroplasty: a diagnostic challenge.
                 - Prognostic factors for bacterial cultures positive for Propionibacterium acnes and other organisms in a large series of revision shoulder arthroplasties performed for stiffness, pain, or loosening.
                 - Prosthesis Failure Within 2 Years of Implantation Is Highly Predictive of Infection
                 - Early Versus Late Culture Growth of Propionibacterium acnes in Revision Shoulder Arthroplasty
                 - Arthroplastic and osteosynthetic infections due to Prop acnes: study of 52 cases, 1995-2002.
                 - Nonunion after clavicle osteosynthesis: High incidence of Propionibacterium acnes.

Propionibacterium acnes: an under-appreciated cause of post-neurosurgical infection.
Origin of Propionibacterium in Surgical Wounds and Evidence-Based Approach for Culturing Propionibacterium from Surgical Sites