title: Prevention of Propionibacterium acnes biofilm formation in prosthetic infections in vitro.
abstract: BACKGROUND
  The role of Propionibacterium acnes in shoulder arthroplasty and broadly in orthopedic prosthetic infections has historically been underestimated, with biofilm formation identified as a key virulence factor attributed to invasive isolates. With an often indolent clinical course, P acnes infection can be difficult to detect and treat. This study investigates absorbable cements loaded with a broad-spectrum antibiotic combination as an effective preventive strategy to combat P acnes biofilms.
  
  
  METHODS
  P acnes biofilm formation on an unloaded synthetic calcium sulfate (CaSO4) bone void filler cement bead was evaluated by scanning electron microscopy over a period of 14 days. Beads loaded with tobramycin alone or vancomycin alone (as comparative controls) and beads loaded with a vancomycin-tobramycin dual treatment were assessed for their ability to eradicate planktonic P acnes, prevent biofilm formation, and eradicate preformed biofilms using a combination of viable-cell counts, confocal microscopy, and scanning electron microscopy.
  
  
  RESULTS
  P acnes surface colonization and biofilm formation on unloaded CaSO4beads was slow. Beads loaded with antibiotics were able to kill planktonic cultures of 106colony-forming units/mL, prevent bacterial colonization, and significantly reduce biofilm formation over periods of weeks. Complete eradication of established biofilms was achieved with a contact time of 1 week.
  
  
  CONCLUSIONS
  This study demonstrates that antibiotic-loaded CaSO4beads may represent an effective antibacterial and antibiofilm strategy to combat prosthetic infections in which P acnes is involved.
authors.affiliation: Southampton National Institute for Health Research Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton National Health Service Foundation Trust, Southampton General Hospital, Southampton, UK; Centre for Biological Sciences, Faculty of Natural and Environmental Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK. Electronic address: rph@soton.ac.uk.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Howlin
authors.affiliation: Centre for Biological Sciences, Faculty of Natural and Environmental Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Winnard
authors.affiliation: Biomedical Imaging Unit, Southampton General Hospital, Southampton, UK.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Angus
authors.affiliation: Centre for Biological Sciences, Faculty of Natural and Environmental Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Connor J
authors.initials: CJ
authors.lastname: Frapwell
authors.affiliation: Southampton National Institute for Health Research Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton National Health Service Foundation Trust, Southampton General Hospital, Southampton, UK; Centre for Biological Sciences, Faculty of Natural and Environmental Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Webb
authors.affiliation: Biocomposites Ltd, Keele, UK.
authors.forename: John J
authors.initials: JJ
authors.lastname: Cooper
authors.affiliation: Biocomposites Ltd, Keele, UK.
authors.forename: Sean S
authors.initials: SS
authors.lastname: Aiken
authors.affiliation: Department of Orthopaedics, Ohio State University Sports Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
authors.forename: Julie Y
authors.initials: JY
authors.lastname: Bishop
authors.affiliation: Southampton National Institute for Health Research Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton National Health Service Foundation Trust, Southampton General Hospital, Southampton, UK; National Centre for Advanced Tribology, Faculty of Engineering and Institute for Life Sciences, University of Southampton, Southampton, UK; Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, OH, USA; Department of Orthopaedics, The Ohio State University, Columbus, OH, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stoodley
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D001843:Bone Cements; D002133:Calcium Sulfate; D016908:Gram-Positive Bacterial Infections / Q000517:prevention & control*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D011425:Propionibacterium acnes; D016459:Prosthesis-Related Infections / Q000517:prevention & control*; D014031:Tobramycin / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D014640:Vancomycin; D014031:Tobramycin; D002133:Calcium Sulfate
keywords: Propionibacterium acnes; antibiotics; biofilm; calcium sulfate; prosthetic infection; shoulder arthroplasty