Alternating magnetic fields (AMF) and linezolid reduce Staphylococcus aureus biofilm in a large animal implant model

J Infect. 2024 Nov;89(5):106271. doi: 10.1016/j.jinf.2024.106271. Epub 2024 Sep 13.

Abstract

Objectives: We aimed to evaluate the effectiveness of alternating magnetic fields (AMF) combined with antibiotics in reducing Staphylococcus aureus biofilm on metal implants in a large animal model, compared to antibiotics alone.

Methods: Metal plates were inoculated with a clinical MRSA strain and then implanted into thirty-three ewes divided into three groups: positive control, linezolid only, and a combination of linezolid and AMF. Animals had either titanium or cobalt-chrome plates and were sacrificed at 5 or 21 days post-implantation. Blood and tissue samples were collected at various time points post-AMF treatment.

Results: In vivo efficacy studies demonstrated significant biofilm reduction on titanium and cobalt-chrome implants with AMF-linezolid combination treatment compared to controls. Significant bacterial reductions were also observed in surrounding tissues and bones. Cytokine analysis showed improved inflammatory responses with combination therapy, and histopathology confirmed reduced inflammation, necrosis, and bacterial presence, especially at 5 days post-implantation.

Conclusions: This study demonstrates that combining AMF with antibiotics significantly reduces biofilm-associated infections on metal implants in a large animal model. Numerical simulations confirmed targeted heating, and in vivo results showed substantial bacterial load reduction and reduced inflammatory response. These findings support the potential of AMF as a non-invasive treatment for prosthetic joint infections.

Keywords: AMF, Alternating magnetic fields; Antibiotic therapy; Biofilm; Inductive heating; Inflammation reduction; Large animal model; Metal implants; Prosthetic joint infections; Staphylococcus aureus.

MeSH terms

  • Animals
  • Anti-Bacterial Agents* / administration & dosage
  • Anti-Bacterial Agents* / pharmacology
  • Anti-Bacterial Agents* / therapeutic use
  • Biofilms* / drug effects
  • Disease Models, Animal
  • Female
  • Linezolid* / pharmacology
  • Linezolid* / therapeutic use
  • Magnetic Fields
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Oxazolidinones / administration & dosage
  • Oxazolidinones / pharmacology
  • Oxazolidinones / therapeutic use
  • Prostheses and Implants / microbiology
  • Prosthesis-Related Infections* / drug therapy
  • Prosthesis-Related Infections* / microbiology
  • Prosthesis-Related Infections* / prevention & control
  • Sheep
  • Staphylococcal Infections* / drug therapy
  • Staphylococcal Infections* / microbiology
  • Staphylococcus aureus / drug effects

Substances

  • Linezolid
  • Anti-Bacterial Agents
  • Oxazolidinones