Experimental acute hematogenous osteomyelitis in mice. I. Histopathological and immunological findings

This study investigated immunological responses to Staphylococcus aureus bo ne infection. Because considerable immunological information is available o n the mouse, a-murine model of acute hematogenous osteomyelitis was establi shed. Osteomyelitis was created in the proximal tibia of C3H/HeJ mice by a tibial epiphyseal fracture followed by intravenous bacterial inoculation wi th Staphylococcus aureus (strain LS-1). Swelling and warmth of the limb was found, and following limb exposure, abscess formation was evident in the p roximal: tibia. Histological examination revealed distortion primarily at t he hypertrophic zone of the physis and polymorphonuclear leukocyte infiltra tion throughout the damaged area of the proximal tibia. Local infection was demonstrated at the fracture site, evidenced by the recovery of Staphyloco ccus aureus following microbiological analysis of tissue specimens. Polymer ase chain reaction was utilized to detect 16S ribosomal prokaryotic nucleic acid to demonstrate that the diagnosis of osteomyelitis could be establish ed in the absence of conventional microbiological techniques. The infected mice had an increase of circulating large leukocytes (granulocytes) and an elevation of total serum immunoglobulin. Flow cytometry revealed significan t increases in splenic B lymphocytes and in lymph-node CD4+ T lymphocytes. These results indicate that an: experimental model of acute hematogenous os teomyelitis that closely resembles the pathology of the disease in humans m ay be consistently induced in mice. Furthermore, marked immunological chang es may be observed in response to the Staphylococcus aureus bone infection.