title: Photodynamic therapy of antibiotic-resistant biofilms in a maxillary sinus model.
abstract: BACKGROUND
  Chronic rhinosinusitis (CRS) is one of the most common chronic conditions in the United States. There is a significant subpopulation of CRS patients who remain resistant to cure despite rigorous treatment regimens including surgery, allergy therapy, and prolonged antibiotic therapy. Antimicrobial photodynamic therapy (aPDT) is a noninvasive nonantibiotic broad spectrum antimicrobial treatment. Our previous in vitro studies demonstrated that aPDT reduced CRS polymicrobial planktonic bacteria and fungi by >99.9% after a single treatment. However, prior to human treatment, the effectiveness of aPDT to eradicate polymicrobial biofilms in a maxillary sinus cavity must be demonstrated. The objective of this study was to demonstrate the effectiveness of a noninvasive aPDT treatment of antibiotic resistant biofilms known to cause CRS in a novel anatomically correct maxillary sinus in vitro model using an enhanced photosensitizer solution.
  
  
  METHODS
  Antibiotic resistant polymicrobial biofilms of Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) were grown in an anatomically correct novel maxillary sinus model and treated with a methylene blue/ethylenediamine tetraacetic acid (EDTA) photosensitizer and 670-nm nonthermal activating light. Cultures of the biofilms were obtained before and after light treatment to determine efficacy of biofilm reduction.
  
  
  RESULTS
  The in vitro maxillary sinus CRS biofilm study demonstrated that aPDT reduced the CRS polymicrobial biofilm by >99.99% after a single treatment.
  
  
  CONCLUSIONS
  aPDT can effectively treat CRS polymicrobial antibiotic resistant Pseudomonas aeruginosa and MRSA biofilms in a maxillary sinus cavity model.
authors: Ear, Nose and Throat Specialty Care of Minnesota, Minneapolis, MN 55414, USA. bielx001@umn.edu
authors: Merrill A
authors: MA
authors: Biel
authors: Lisa
authors: L
authors: Pedigo
authors: Aaron
authors: A
authors: Gibbs
authors: Nicolas
authors: N
authors: Loebel
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D018441:Biofilms / Q000187:drug effects*; D002908:Chronic Disease; D004492:Edetic Acid / Q000627:therapeutic use; D006801:Humans; D008443:Maxillary Sinus / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000502:physiology; D008751:Methylene Blue / Q000627:therapeutic use; D008953:Models, Anatomic; D010778:Photochemotherapy / Q000379:methods*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology; D012220:Rhinitis / Q000188:drug therapy* / Q000382:microbiology; D012852:Sinusitis / Q000188:drug therapy* / Q000382:microbiology; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D004492:Edetic Acid; D008751:Methylene Blue