Exploring a Novel, Non-Invasive Treatment for Prosthetic Joint Infection

Periprosthetic joint infection (PJI) is a very prevalent consequence of implant surgery. The surface of the prosthesis provides a favorable environment for the growth of bacterial biofilms, which are notorious for being resistant to conventional antibiotics. The current treatment for PJI involves re-opening the surgical site and replacing the prosthesis, a very costly procedure that diminishes patient quality of life. Recently, a non-invasive procedure has been developed that utilizes high frequency alternating magnetic fields (AMF) to destroy biofilms via induction heating. Our research was focused on both optimizing and further characterizing the cytotoxicity of this treatment method on Staphylococcus aureus and Pseudomonas aeruginosa, two biofilm-forming pathogens commonly implicated in PJI. The organisms used for these experiments were Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms were grown on stainless steel rings or washers, to model the surface of implanted prosthetics. P. aeruginosa was grown statically in MH2 media at 37°C for 48 hours. S. aureus was grown statically in Tryptic Soy Broth media supplemented with 0.5% glucose and 3.0% NaCl at 37°C for 48 hours. Soaking the stainless steel ring/washer in a 20% Human Plasma solution overnight at 4°C greatly enhanced S. aureus biofilm formation. AMF continuous dosing was performed at 20 watts, up to 15 minutes. AMF intermittent dosing was performed using 1 second duration, 670 watt pulses every 10 minutes, up to 6 hours. The results indicated that S. aureus biofilms were eradicated more effectively than P. aeruginosa biofilms when treated with intermittent AMF exposure. Specifically, there was a 2.6-log reduction in S. aureus biofilm CFU after 30 minutes of AMF exposure, with CFUs reaching the limit of detection after 3 hours. Corresponding studies in P. aeruginosa showed a 1.3-log reduction in biofilm CFU after 30 minutes of AMF exposure, with CFUs not reaching the limit of detection after 6 hours. In an ongoing study, ciprofloxacin was administered alongside AMF exposure to investigate any potential synergistic effects on P. aeruginosa biofilm eradication. While the data produced this summer was exclusively in vitro, the results give insight on how AMF might be applied in the clinical treatment of PJI. The observed cytotoxicity combined with the non-invasive nature of AMF suggest significant promise for a much more desired method of PJI treatment for common pathogens.