Vertebral osteomyelitis and a forgotten dog bite in an immunocompetent patient

A woman in her 60s presented with a three-week history of progressive subacute back pain without neurological deficits. MRI of the lumbar spine demonstrated necrosis at the L3-L4 disc and adjacent vertebral bodies, raising suspicion for malignancy or infection. Two image-guided bone biopsies were nondiagnostic. A peripheral infectious disease workup was similarly unremarkable. Owing to the persistent concern for infection, 16S ribosomal RNA sequencing was performed on biopsy samples, which identified Capnocytophaga canimorsus. Only after receiving this result did the patient recall a minor dog bite sustained six weeks prior to symptom onset. She was managed with an extended course of oral antibiotics with complete clinical recovery. This case illustrates the capacity of C. canimorsus to cause insidious vertebral osteomyelitis in immunocompetent individuals, underscores the diagnostic utility of 16S rRNA sequencing in culture-negative infections, and highlights the critical importance of a detailed exposure history in atypical clinical presentations.