Cutibacterium acnes Infection of the Acromioclavicular Joint: A Case Report and Review of the Literature

Cutibacterium acnes (C. acnes) is a slow growing, anaerobic gram-positive bacillus that resides as a commensal organism on the skin, particularly in sebaceous areas such as the axilla1. While historically regarded as a contaminant, its clinical significance has become increasingly recognized in orthopedic surgery, particularly in postoperative shoulder infections and cases involving orthopedic implants4. Its ability to persist intracellularly and elicit low grade inflammation allows the bacterium to evade immune responses and delay diagnosis, often leading to poor recognition in clinical settings12.