Laboratory characteristics in reactive and bacterial arthritis
| Characteristics | Reactive arthritis | Bacterial arthritis |
| ESR mm 1st h (median) | 79 | 78 |
| CRP g/l (median) | 129 | 125 |
| Peripheral blood | ||
| Leucocytes∗109/l (median) | 9.9 | 11.6 |
| Synovial fluid (knee) | ||
| Leucocytes∗109/l (median) | 19.0 | 36.0 |
| Granulocytes; % of leukocytes (median) | 85 | 89 |
These findings are based on a study of 20 patients with B27 associated reactive arthritis and of 20 patients with culture positive bacterial arthritis.61 Reactive arthritis was caused byYersinia (14 patients),Salmonella (4) orChlamydia (2).