Influence of superoxide dismutase on staphylococcal arthritis--a histological and biochemical investigation using an experimental animal model.

The effect of superoxide dismutase (SOD) on staphylococcal arthritis has not been successfully evaluated to date. A suitable animal model has been developed to investigate a possible correlation. Using 16 rabbits divided into four groups, we injected the knee joints of two groups with Staphylococcus aureus and the other two with NaCl. One group in each of the two treatment groups was also injected with SOD. Blood samples and samples of joint fluid were taken at 12 hour intervals. Lipids were measured in plasma and joint fluid. The joints were examined macroscopically and microscopically using a scoring system to quantitate the deterioration of joint structures. Lipid peroxide concentrations measured in plasma differed in each of the groups, with higher values found in animals with septic arthritis compared with controls. The estimations made of lipid peroxide in joint fluid also displayed extreme variability, with the highest values found in animals with Staphylococcal arthritis treated with SOD. Histological examination also verified that the infected joints injected with SOD showed significantly more inflammation, a higher amount of bacteria in the joint cavity, and more distinct joint damage than joints injected only with bacteria. The mechanisms responsible for this SOD effect remain to be determined.