A Novel Rat Model of Chronic Spinal Implant-Associated Infection

Abstract

Spinal implant-associated infection is a rare but devastating complication. The prevalence of antibiotic-resistant pathogens like methicillin-resistant Staphylococcus aureus bacteria (MRSA) contribute to poorer outcomes for post-surgical spine infections due to their enhanced virulence and persistence mechanisms. This is particularly true in spinal fusion surgeries, in which infection can prevent the bone formation needed to support the spine long-term. While there are animal models of spinal implant-associated infection, this thesis describes the first model to incorporate an implant that is anchored in the vertebral bodies and spans one vertebral level. This simultaneously mimics placement of the pedicle screws and rods used in spinal surgeries and provides an abiotic surface for bacteria to build protective biofilm structures. Using a bioluminescent strain of MRSA to track bacterial burden over the course of the infection, we found that the model was successful in establishing a persistent (8-week) infection localized to the spinal implant. This rat model of spinal instrumentation infection can be used to study pathophysiology of spinal implant infections as well as test novel therapeutics. We are currently adapting the model to include a spinal fusion procedure to assess the performance of antimicrobial bone graft materials in reducing or preventing infection while forming healthy new bone.