Using magnets to destroy biofilms on implants
We all know that high temperatures kill bacteria, but use in patients is impractical to say the least, do magnets hold the key?
A new study in Scientific Reports proposes a way to kill bacteria on implanted metal prosthetics with heat. They do this by applying a magnetic field to the metal prosthetic which can be done completely none invasively. When they switch the polarity of the field at very high frequencies, the metal heats up, but only at the surface.
The research team headed by David Greenberg from UT Southwester Medical Center in Texas saw that this heating was enough to kill the biofilm localised on the prosthetic surface but did not cause any tissue damage. This non-invasive approach could be used to treat infection in the future, as well as combined with current antibiotics to improve their effectiveness.
Read more below:
Treatment of prosthetic joint infection (PJI) usually requires surgical replacement of the infected joint and weeks of antibiotic therapy, due to the formation of biofilm. We introduce a non-invasive method for thermal destruction of biofilm on metallic implants using high-frequency (>100 kHz) alternating magnetic fields (AMF). In vitro investigations demonstrate a >5-log reduction in bacterial counts after 5 minutes of AMF exposure. Confocal and scanning electron microscopy confirm removal of biofilm matrix components within 1 minute of AMF exposure, and combination studies of antibiotics and AMF demonstrate a 5-log increase in the sensitivity of Pseudomonas aeruginosa to ciprofloxacin. Finite element analysis (FEA) simulations demonstrate that intermittent AMF exposures can achieve uniform surface heating of a prosthetic knee joint. In vivo studies confirm thermal damage is confined to a localized region (<2 mm) around the implant, and safety can be achieved using acoustic monitoring for the presence of surface boiling. These initial studies support the hypothesis that AMF exposures can eradicate biofilm on metal implants, and may enhance the effectiveness of conventional antibiotics.
Employing high-frequency alternating magnetic fields for the non-invasive treatment of prosthetic joint infections
Rajiv Chopra, Sumbul Shaikh, Yonatan Chatzinoff, Imalka Munaweera, Bingbing Cheng, Seth M. Daly, Yin Xi, Chenchen Bing, Dennis Burns & David E. Greenberg
Scientific Reports 7, Article number: 7520 (2017)