Effective Biofilm Eradication on Orthopedic Implants with Methylene Blue Based Antimicrobial Photodynamic Therapy In Vitro

• Main Authors: Julia Prinz (Author), Marianne Wink (Author), Sonja Neuhaus (Author), Markus C. Grob (Author), Heinrich Walt (Author), Philipp P. Bosshard (Author), Yvonne Achermann (Author)
• Format: Book
• Published: MDPI AG, 2023-01-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics12010118; 2079-6382
• Keywords: photodynamic therapy; methylene blue; biofilm; orthopedic implants; periprosthetic joint infection; in vitro; Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 12, Iss 1, p 118 (2023)

Periprosthetic joint infections (PJI) are difficult to treat due to biofilm formation on implant surfaces, often requiring removal or exchange of prostheses along with long-lasting antibiotic treatment. This in vitro study investigated the effect of methylene blue photodynamic therapy (MB-PDT) on PJI-causing biofilms on different implant materials. MB-PDT (664 nm LED, 15 J/cm²) was tested on different <i>Staphylococcus aureus, Staphylococcus epidermidis</i>, <i>Escherichia coli</i> and <i>Cutibacterium acnes</i> strains in both planktonic form and grown in early and mature biofilms on prosthetic materials (polyethylene, titanium alloys, cobalt-chrome-based alloys, and bone cement). The minimum bactericidal concentration with 100% killing (MBC_100%) was determined. Chemical and topographical alterations were investigated on the prosthesis surfaces after MB-PDT. Results showed a MBC_100% of 0.5-5 μg/mL for planktonic bacteria and 50-100 μg/mL for bacteria in biofilms-independent of the tested strain, the orthopedic material, or the maturity of the biofilm. Material testing showed no relevant surface modification. MB-PDT effectively eradicated common PJI pathogens on arthroplasty materials without damage to the materials, suggesting that MB-PDT could be used as a novel treatment method, replacing current, more invasive approaches and potentially shortening the antibiotic treatment in PJI. This would improve quality of life and reduce morbidity, mortality, and high health-care costs.