Noninvasive Treatment of Biofilm on Metallic Implants

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Project Summary Biofilm-related infections are a major complication for orthopedic implants used to replace or repair injured bones and joints. Biofilms are aggregates of bacteria and extracellular substances which can form on any surface, including the surface of implanted medical devices. Bacteria within biofilms are protected from antibiotics and the immune system, and can cause recurrent infection even after a prolonged course of therapy. The treatment of these infections is prolonged and costly; removal and replacement of the infected hardware, weeks of antibiotic administration, and extended hospital stays are usually required. Approximately 70 percent of these biofilm- infections are caused by gram-positive pathogens, such as Staphylococcus aureus, with the remaining caused by gram-negative pathogens, such as Pseudomonas aeruginosa. Increasing rates of antibiotic resistance in these pathogens are further complicating patient treatment. An innovative non-invasive approach for the treatment of biofilm on metallic implants can be achieved through the use of an alternating magnetic fields (AMF). When metal prostheses are exposed to AMF, electrical currents are induced on their surface, resulting in rapid heating which can destroy biofilm. This method of treatment is highly effective at killing the bacterial components of the biofilm, and can be used in concert with traditional antimicrobials to achieve complete treatment of the infection. The research team hypothesizes that focused heating of an in vivo metallic implant surface through the delivery of AMF will be bactericidal to pathogens embedded within an attached biofilm, will increase their sensitivity to antimicrobial agents and will be safe in vivo. The overall goals of this study are to evaluate biofilm eradication by AMF exposure in both small and large animal models of implant infection, as well as design and characterize a prototype AMF device suitable for treating human implant infections. This proposal aims to answer critical questions regarding the optimal power, temperature, and total exposure time that will be both safe and effective. This would represent a significant advance in the ability to treat implants in situ, avoiding millions of surgeries and the corresponding billions of dollars associated with them.