Pathogenesis and Control of Biofilm-Associated Implant Infections in Veterinary Orthopedic Surgery: A Mechanistic Study in Nigerian Teaching Hospitals

Biofilm-associated infections on orthopedic implants represent among the most difficult-to-treat complications of fracture fixation surgery in veterinary patients, characterized by antimicrobial tolerance, chronicity, and frequent implant failure requiring revision surgery. This doctoral study investigates the pathogenic mechanisms, microbial ecology, and potential control strategies for biofilm-associated implant infections in canine and bovine orthopedic patients at teaching hospitals in the South East, North West, and South South geopolitical zones of Nigeria between 2021 and 2024. Implant surfaces retrieved from clinical infections were subjected to scanning electron microscopy and confocal laser scanning microscopy for biofilm structure characterization. Metagenomic analysis of biofilm communities using Oxford Nanopore long-read sequencing was performed on 44 infected implants. In vitro biofilm prevention studies evaluated three investigational surface coating strategies including chitosan-silver nanoparticle, vancomycin-loaded hydrogel, and bacteriophage-impregnated coatings. Staphylococcus pseudintermedius and Pseudomonas aeruginosa were the most prevalent biofilm-forming species in 71% and 21% of confirmed biofilm infections respectively. Metagenomic analysis revealed polymicrobial biofilm communities with synergistic resistance gene transfer in 38% of cases. Chitosan-silver nanoparticle coatings demonstrated the greatest in vitro biofilm inhibition at 87% reduction in colony forming units relative to uncoated controls. These mechanistic findings provide original contributions to the understanding of veterinary implant biofilm ecology in Nigeria and identify candidate anti-biofilm surface strategies for pre-clinical development targeting the orthopedic infection burden in Nigerian teaching hospital patients. Keywords: biofilm infection, orthopedic implant, Staphylococcus pseudintermedius, implant coating, veterinary surgery.