Table 2.
Histopathological and microbiological data from patients with chronic BJI due to C. acnes
| Patients | Type of implant/location | Samples | No. of positive intraoperative culture to C. acnes* | Sinus tract | PMNs /5 HPFs** |
Infection according Mirra's criterion (≥ 5 PMNs/5 HPFs) | Plasma cells /5 HPFs** |
Infection according CRIOAc Lyon's criterion (≥ 5 Plasma cells /5 HPFs) |
Diagnosis restored by adding CRIOAc Lyon's criterion to Mirra's criterion | Granulation tissue | Fibrin | Necrosis | Giant cells |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | PJ/knee | bone/synovial | 3 | - | 0 | - | 2-5 | - | - | + | + | - | + |
| 2 | OS/shoulder | bone/synovial | 8 | - | ≥5 | I | ≥5 | I | - | - | + | - | + |
| 3 | PJ/hip | bone/synovial | 3 | - | EX | EX | EX | EX | EX | EX | EX | EX | EX |
| 4 | PJ/hip | bone/synovial | 4 | - | ≥5 | I | ≥5 | I | - | + | + | - | - |
| 5 | OS/parietal bone | bone | 2 | - | 0 | - | ≥5 | I | + | - | - | - | - |
| 6 | OS/parietal bone | bone | 2 | - | 0 | - | 2-5 | - | - | - | - | - | + |
| 7 | PJ/knee | bone/synovial | 1*** | - | 0 | - | 2-5 | - | - | + | + | - | - |
| 8 | PJ/hip | bone/synovial | 1*** | - | <2 | - | <2 | - | - | + | + | - | - |
| 9 | PJ/knee | bone/synovial | 2 | - | <2 | - | 2-5 | - | - | - | + | - | + |
| 10 | PJ/hip | bone/synovial | 7 | - | ≥5 | I | ≥5 | I | - | + | + | - | - |
| 11 | PJ/hip | bone/synovial | 5 | - | ≥5 | I | <2 | - | - | + | - | - | - |
| 12 | PJ/hip | bone/synovial | 5 | + | ≥5 | I | 2-5 | - | - | + | + | - | - |
| 13 | PJ/knee | bone/synovial | 4 | - | ≥5 | I | ≥5 | I | - | + | + | - | + |
| 14 | PJ/hip | bone/synovial | 6 | - | ≥5 | I | ≥5 | I | - | - | + | - | + |
| 15 | PJ/hip | bone/synovial | 5 | - | <2 | - | 2-5 | - | - | + | + | - | - |
| 16 | PJ/knee | bone/synovial | 2 | - | <2 | - | ≥5 | I | + | - | + | - | - |
| 17 | PJ/hip | bone/synovial | 3 | - | ≥5 | I | ≥5 | I | - | + | + | - | + |
| 18 | PJ/hip | synovial | 1*** | + | 0 | - | ≥5 | I | + | + | - | - | - |
| 19 | PJ/hip | bone/synovial | 3 | - | ≥5 | I | ≥5 | I | - | + | + | - | - |
| 20 | OS/femur | bone/synovial | 6 | - | ≥5 | I | ≥5 | I | - | + | + | + | - |
| 21 | OS/ankle | bone | 7 | - | 0 | - | ≥5 | I | + | - | - | - | - |
| 22 | OS/femur | bone | 5 | - | 2-5 | - | ≥5 | I | + | + | + | + | - |
| 23 | OS/femur | bone | 2 | - | 0 | - | ≥5 | I | + | + | + | - | - |
| 24 | OS/humerus | bone | 4 | - | ≥5 | I | ≥5 | I | - | + | - | - | - |
| 25 | OS/femur | bone | 4 | + | ≥5 | I | ≥5 | I | - | - | + | - | - |
HPFs: high-power fields; I: Infected; -: absence; +: presence; EX: excluded; PJ: Prosthetic joint; OS: Osteosynthesis.
*All positive cultures for C. acnes were monomicrobial and performed on separate deep samples collected intraoperatively from the site of infection. **PMNs per field/5 HPFs and plasma cells per field/5 HPFs with 4 possible scores: 0, <2, 2-5, ≥5. Patients were considered as infected, if they had ≥5 plasma cells and/or PMNs per field/5 high-power fields. *** Patients with only one C. acnes positive culture were not included in the final histopathological analysis, in order to analyse the proven C. acnes infections only.