Poly-N-acetylglucosamine mediates Cutibacterium acnes biofilm formation and biocide resistance

Biofilm formation likely plays an important role in the pathogenesis of implant-related infections caused by Cutibacterium acnes. Biofilms protect bacteria from antimicrobials and host defenses which makes biofilm-related infections difficult to treat. Here we demonstrate that the exopolysaccharide poly-N-acetylglucosamine (PNAG) contributes to C. acnes biofilm formation in vitro. By treating C. acnes cells and biofilms with the PNAG-degrading enzyme dispersin B, we found that PNAG mediates the attachment of C. acnes cells to polystyrene rods and the formation C. acnes biofilms in glass and polypropylene tubes. We further show that PNAG protects C. acnes biofilm cells from killing by tetracycline and benzoyl peroxide. PNAG may play an important role in biofilm formation, antibiotic tolerance, and virulence in this opportunistic pathogen.