Knee joint infections with Staphylococcus aureus and Micrococcus species.

In rabbit knees 600 Staphylococcus aureus organisms produced progressive infection in 50 per cent of the knees injected, whereas 5.3 times 10-7 Micrococcus species caused only transient colonization of the joints. Methicillin, cephacetrile, and clindamycin administered before injection of the staphylococci gave protection. Stainless-steel particles in the knee did not increase susceptibility to infection from injected micrococci but did make established micrococcal infections more persistent. Knees containing steel debris failed to become infected during prolonged staphylococcal bacteremia. Injected autologous blood, either fresh or three days old, did not increase susceptibility to infection. Large doses of steroids, given systemically or intraarticularly, decreased resistance to micrococcal infection and increased the destruction caused by infection due to this organism.