Antibiotic treatment insufficient for established septic arthritis. Staphylococcus aureus experiments in rabbits.

We treated septic arthritis of the knee in 38 rabbits with cloxacillin i.m. once and twice daily combined with probenecid for 7 or 21 days, respectively, or with only cloxacillin i.m. thrice daily for 7 days. The animals were killed weekly in groups up to 5 weeks after inoculation. Aspirated cultures obtained after 4 days of treatment were always negative. Histologic specimens revealed progressive joint destruction, but at a slower rate after frequent treatment independent of the period. We concluded that antibiotic therapy alone could not prevent destruction of articular cartilage once bacterial arthritis was established.