Published online Aug 18, 2016. doi: 10.5312/wjo.v7.i8.467
Peer-review started: March 27, 2016
First decision: May 13, 2016
Revised: May 23, 2016
Accepted: June 27, 2016
Article in press: June 29, 2016
Published online: August 18, 2016
AIM: To test antibiotic-loaded coating for efficacy in reducing bacterial biofilm and development of osteomyelitis in an orthopaedic model of implant infection.
METHODS: Phosphatidylcholine coatings loaded with 25% vancomycin were applied to washed and sterilized titanium wires 20 mm in length. A 10 mm segment was removed from rabbit radius (total = 9; 5 coated, 4 uncoated), and the segment was injected with 1 × 106 colony forming units (CFUs) of Staphylococcus aureus (UAMS-1 strain). Titanium wires were inserted through the intramedullary canal of the removed segment and into the proximal radial segment and the segment was placed back into the defect. After 7 d, limbs were removed, X-rayed, swabbed for tissue contamination. Wires were removed and processed to determine attached CFUs. Tissue was swabbed and streaked on agar plates to determine bacteriological score.
RESULTS: Antibiotic-loaded coatings resulted in significantly reduced biofilm formation (4.7 fold reduction in CFUs; P < 0.001) on titanium wires and reduced bacteriological score in surrounding tissue (4.0 ± 0 for uncoated, 1.25 ± 0.5 for coated; P = 0.01). Swelling and pus formation was evident in uncoated controls at the 7 d time point both visually and radiographically, but not in antibiotic-loaded coatings.
CONCLUSION: Active antibiotic was released from coated implants and significantly reduced signs of osteomyelitic symptoms. Implant coatings were well tolerated in bone. Further studies with additional control groups and longer time periods are warranted. Antibiotic-loaded phosphatidylcholine coatings applied at the point of care could prevent implant-associated infection in orthopaedic defects.
Core tip: We report infection preventative results of a novel antibiotic-loaded coating in a severe contaminated model of orthopaedic infection. Phosphatidylcholine coatings loaded with 25% vancomycin, which can be applied to implants immediately prior to implantation, significantly reduced staphylococcal adherence to intramedullary titanium wires in rabbits. Reduction in bacterial load on implants and in tissue for antibiotic-loaded coatings accompanied reduction in swelling and pus formation. Mild inflammatory responses were noted with coated implants compared to uncoated infected controls. This preliminary short term study demonstrates the clinical potential of these broadly applicable coatings and the need for further characterization and development.