Sensitization of Biofilms to Antibiotics Via Low- Frequency Alternating Magnetic Fields for Safer Implant Therapies

Introduction: An increasing proportion of surgically implanted knee and hip joints become infected with bacterial biofilms, which are notoriously resistant to antibiotic therapies.Despite the use of aggressive intravenous antibiotic treatment, revision surgery is required in many cases to remove the infected prosthetic and treat the life-threatening infection.Such revision surgery is physically demanding for the surgeon, is expensive, and can result in significant tissue loss, necessitating prolonged patient recuperation and recovery. Methods:In this article, we report our progress on the development of a coil-based AC Electromagnetic Field (EMF) device that produces a controlled Alternating Magnetic Field (AMF) to enhance antibiotic efficacy against biofilms.To optimize treatment, we sought to establish whether lower-frequency EMF-generated AMFs, which reduce unwanted tissue heating, could improve biofilm susceptibility to antibiotics.Biofilms were grown on various solid substrates to model surgical implants.After exposure to AMFs and antibiotic treatment, the number of bacterial cells in the biofilms were enumerated by Colony-Forming Units (CFU) or optical density.Results: Two AMF generators were designed to operate between 30 and 60 kHz and assembled.Staphylococcus aureus (MRSA M2) biofilms propagated on various solid substrates were subjected to AMF which heats the substrates by induction via eddy currents.A 30-second increase in temperature to 45 o C was sufficient to increase bacterial sensitivity to vancomycin and other antibiotics.CFU decreased by up to 4 log 10 following combined AMF and vancomycin treatment. Conclusions:This EMF-based low-frequency AMF modulation strategy shows promise as a basis for developing non-invasive treatment of biofilm infections and may serve as a prophylactic measure following surgical implantations.