Of these, neutrophil collagenase (MMP8) was most consistent with a fold change of 22.9 when comparing septic arthritis before (PID1) and post eradication of joint infection (PID4), and a 4.2 fold change when comparing septic arthritis and experimentally induced non-septic synovitis PID1 (Table 3). Here, MMP8 is linked to bacterial arthritis.