The role of Propionibacterium acnes in acne pathogenesis: facts and controversies.

We have come a long way since 1896, when it was first suggested that Propionibacterium acnes, found in acne lesions, was the cause of acne. Although several lines of evidence suggest the direct role of P acnes in acne, the mechanism by which P acnes contributes to the pathogenesis of acne is debated. The importance of P acnes in the induction and maintenance of the inflammatory phase of acne has been established. Emerging data that inflammatory events occur in the very earliest stages of acne development have reopened the debate about the potential involvement of this microorganism in comedogenesis and acne initiation.