Association of Intra-articular Ozone/Prolozone Injections With Cutibacterium acnes Infection in a Shoulder With...

Septic arthritis following joint injection/aspiration is an uncommon and challenging orthopaedic disease. We report a unique case of a 58-year-old non-diabetic, non-obese female with no prior shoulder surgery who developed septic arthritis of the right shoulder due to the anaerobic bacterium Cutibacterium acnes (C. acnes), identified from deep-tissue samples obtained during arthroscopic debridement. The case is notable for a history of pseudogout and multiple recent intra-articular injections in the affected shoulder. The patient received four shoulder joint (glenohumeral) ozone/prolozone injections over a one-month period for shoulder pain attributed to pseudogout with glenohumeral osteoarthritis. Within one week of the final ozone/prolozone injection, the pain markedly worsened, and a large subdeltoid/glenohumeral effusion was detected grossly and via MR imaging. The subdeltoid effusion was confluent with the glenohumeral joint through a nontraumatic rotator cuff tear. Initial management included aspiration of the effusion (55 mL) and corticosteroid injection. This was followed by three additional aspirations over the next three months, one of which also included another corticosteroid injection. Hence, there were eight independent percutaneous needle punctures into the shoulder joint/effusion over six months. The tissue cultures that grew C. acnes were obtained five weeks after the final (eighth) aspiration/injection. This report highlights five key considerations and issues of this highly unusual case: (1) the potential causal association between repeated intra-articular injections/aspirations and subsequent septic arthritis with C. acnes; (2) the rare occurrence of septic arthritis following intra-articular ozone/prolozone injections; (3) the association with pseudogout and the later-postulated diagnosis of seronegative rheumatoid arthritis, (4) the potential value of enhanced skin preparation protocols in reducing C. acnes infection risk; and (5) the challenge of attributing causality, given that C. acnes can exist as a native joint commensal organism or as a culture contaminant, with another organism being the true pathogen (e.g., coagulase-negative Staphylococci).