Scintigraphic Patterns of Indium-111 Oxine-Labeled White Blood Cell Imaging of Gram-Negative versus Gram-Positive Vertebral Osteomyelitis

Objective: The goal of the study was to investigate whether or not gram-negative organisms that secrete antichemotactic factors cause the nonaccumulation pattern of ¹¹¹In-oxine-labeled white blood cell (¹¹¹In-WBC) scans. Materials and Methods: Staphylococcus aureus (gram-positive) (group 1) was injected into 25 rabbits and Escherichia coli (gram-negative) (group 2) into another 25 to induce infection in the lumbar vertebrae or left thigh bone (femur). Sixteen successfully infected and surviving rabbits from each group were used for imaging and analysis. Of the 16 rabbits, each group included 8 with vertebral infection and 8 with femur infection. For imaging, each rabbit was injected intravenously with 11.1 MBq (300 μCi) ¹¹¹In-WBC, and images were acquired 24 h later. Microscopic histopathology was performed after decalcification to confirm osteomyelitis. Results: The ¹¹¹In-WBC accumulation was observed in 7 (87.5%) of the 8 rabbits infected with S. aureus in the vertebrae and thigh bone. Of the rabbits infected with the gram-negative vertebrae, 1 (12.5%) showed little accumulation of ¹¹¹In-WBC. Of the 8 rabbits with gram-negative-infected femurs, 1 had high accumulation and another had low accumulation of ¹¹¹In-WBC, while the rest did not show any uptake. Osteomyelitis was confirmed by histopathology in all the successfully infected rabbits used for imaging. Conclusion: In the majority of the gram-positive-infected rabbit vertebrae there was high accumulation of ¹¹¹In-WBC. However, no accumulation of ¹¹¹In-WBC was observed in most of the vertebrae infected with gram-negative organisms, which release antichemotactic factors that prevent adequate accumulation of WBC at the infected area.