Cutibacterium acnes, previously known as Propionibacterium acnes, is a gram-positive, anaerobic bacterium commonly found on human skin. It plays a significant role in the pathogenesis of acne vulgaris by colonizing sebaceous follicles, promoting inflammation, and contributing to comedone formation. While generally commensal, its overgrowth and metabolic byproducts can trigger immune responses and follicular damage, leading to various acne lesions. Research also links it to opportunistic infections, particularly in medical device-related cases.