Antimicrobial photodynamic therapy—a promising treatment for prosthetic joint infections

• Published in: Lasers in medical science 2018-04, Vol.33 (3), p.523-532
• Main Authors: Briggs, Timothy, Blunn, Gordon, Hislop, Simon, Ramalhete, Rita, Bagley, Caroline, McKenna, David, Coathup, Melanie
• Format: Article
• Language: English
• Subjects: Alloys - pharmacology; Anti-Infective Agents - pharmacology; Anti-Infective Agents - therapeutic use; Antimicrobial agents; Bacteria; Biocompatibility; Biofilms; Biofilms - drug effects; Coating effects; Dentistry; Dose-Response Relationship, Radiation; Drug resistance; Growth inhibition; Humans; Hydroxyapatite; Infections; Irradiance; Joint diseases; Joints - microbiology; Lasers; Medicine; Medicine & Public Health; Methicillin; Methicillin-Resistant Staphylococcus aureus - drug effects; Methylene blue; Methylene Blue - pharmacology; Methylene Blue - therapeutic use; Morbidity; Optical Devices; Optics; Original; Original Article; Photochemotherapy; Photodynamic therapy; Photonics; Photosensitizing Agents - pharmacology; Photosensitizing Agents - therapeutic use; Plankton - drug effects; Prostheses; Prostheses and Implants; Prosthesis-Related Infections - drug therapy; Protective coatings; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Quantum Optics; Staphylococcal Infections - drug therapy; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus epidermidis; Staphylococcus epidermidis - drug effects; Staphylococcus infections; Studies; Surgical implants; Titanium; Titanium - pharmacology
• ISSN: 0268-8921; 1435-604X
• DOI: 10.1007/s10103-017-2394-4

Periprosthetic joint infection (PJI) is associated with high patient morbidity and a large financial cost. This study investigated Photodynamic Therapy (PDT) as a means of eradicating bacteria that cause PJI, using a laser with a 665-nm wavelength and methylene blue (MB) as the photosensitizer. The effectiveness of MB concentration on the growth inhibition of methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis , Pseudomonas aeruginosa and Acinetobacter baumannii was investigated. The effect of laser dose was also investigated and the optimized PDT method was used to investigate its bactericidal effect on species within planktonic culture and following the formation of a biofilm on polished titanium and hydroxyapatite coated titanium discs. Results showed that Staphylococci were eradicated at the lowest concentration of 0.1 mM methylene blue (MB). With P. aeruginosa and A. baumannii , increasing the MB concentration improved the bactericidal effect. When the laser dose was increased, results showed that the higher the power of the laser the more bacteria were eradicated with a laser power ≥ 35 J/cm 2 and an irradiance of 35 mW/cm 2 , eradicating all S. epidermidis . The optimized PDT method had a significant bactericidal effect against planktonic MRSA and S. epidermidis compared to MB alone, laser alone, or control (no treatment). When biofilms were formed, PDT treatment had a significantly higher bactericidal effect than MB alone and laser alone for all species of bacteria investigated on the polished disc surfaces. P. aeruginosa grown in a biofilm was shown to be less sensitive to PDT when compared to Staphylococci, and a HA-coated surface reduced the effectiveness of PDT. This study demonstrated that PDT is effective for killing bacteria that cause PJI.