Vertebral remodeling with denosumab after infection control in Escherichia coli spondylodiscitis: case report

Infectious spondylodiscitis can cause progressive vertebral destruction and instability even after infection control, and some patients decline or are unsuitable for surgery. We report a 67-yr-old man with poorly controlled type 2 diabetes mellitus and hypertension who developed Escherichia coli bacteremia and subsequent infectious spondylodiscitis. Four months after treatment of a traumatic open tibial wound with debridement and split-thickness skin grafting, he presented with progressive low back pain, intermittent fever, and systemic illness with acute kidney injury and hepatic dysfunction. A distal common bile duct stone was treated endoscopically, but fever persisted. A gallium-67 scan raised suspicion for L2-L3 involvement, and LS MRI demonstrated L2-L3 infectious spondylodiscitis with extensive paraspinal and epidural inflammatory changes and bilateral psoas abscesses. CT-guided aspiration and bone biopsy were culture-negative. He improved clinically after approximately 5 wk of antimicrobial therapy and declined operative debridement or stabilization. One week after completing antibiotics, denosumab (60 mg, s.c.) was administered. Given that denosumab is not a guideline-supported therapy for infectious spondylodiscitis, it was used off-label as a speculative adjunct to suppress inflammation-associated bone resorption; a second dose was given 6 mo later. Back pain and function improved with bracing, and serial radiographs showed new bone formation along the superior endplate of L3 with progressive remodeling. At 6-yr follow-up, the patient remained free of adverse effects and demonstrated spontaneous fusion of L2 and L3 with sustained symptom relief. This report is descriptive and hypothesis-generating. The observed remodeling may also reflect expected post-infectious healing under conservative management. Nevertheless, the course raises a testable hypothesis that carefully timed antiresorptive therapy after confirmed infection control may support structural recovery in selected nonoperative patients with marked infection-related vertebral osteolysis.