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 non-invasive non-antibiotic 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. Objective The objective of this study was to demonstrate the effectiveness of a non-invasive 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 MRSA were grown in an anatomically correct novel maxillary sinus model and treated with a methylene blue/EDTA photosensitizer and 670nm non-thermal 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.

Future topical medications in chronic rhinosinusitis

“…In 2011, they described impressive in‐vitro results showing a reduction of >99.9% of CRS polymicrobial biofilm after a single PDT treatment . Their subsequent studies demonstrated safety of PDT treatment on a living human ciliated respiratory mucosal model, and effectiveness in a maxillary sinus model, matching previous results, with a reduction of the CRS polymicrobial biofilms of P aeruginosa and MRSA by >99.99% after a single treatment with a methylene blue/ethylene‐diamine tetraacetic acid (EDTA) photosensitizer and 670‐nm nonthermal activating light …”

Understanding the Role of Biofilms and Superantigens in Chronic Rhinosinusitis

“…Once activated by laser light, these dyes induce photodamage to inner organelles and promote apoptosis. In a silicone model of the human maxillary sinus inoculated with MRSA and antibiotic resistant P. aeruginosa , Biel et al demonstrated a greater than 99.9% reduction of biofilms grown from each species after a single treatment of aPDT [80]. aDPT has also demonstrated efficacy in preventing surgical site infections when used in pre-operative decolonization therapy in conjunction with chlorhexidine body wipes, in the treatment of chronic periodontitis, and in reducing biofilm formation on orthopedic prosthetic devices [81–83].…”

Biofilm-based Healthcare-associated Infections

“…Signifi cant preclinical studies have been performed demonstrating the safety and effectiveness of methylene blue and 670 nm aPDT (Sinuwave Inc., Bothell, WA) for treatment of CRS (Biel et al 2011a ;Biel et al 2012 ;Biel et al 2013 ). Osaki described the regression of polypoid rhinosinusitis in a dog after benzporphyrin derivative PDT with control of disease at 10 months (Osaki et al 2012 ).…”