Abstract
Aim
Treatment of enterococcal periprosthetic joint infections (PJI) is challenging due to heterogeneous pathogenesis, non-standardized management strategies and lack of biofilm-active antibiotics. Previous studies report treatment success from 50–76%. We evaluated the characteristics and outcome of enterococcal PJI, in particular the influence of antimicrobial treatment regimens.
Method
Consecutive patients with enterococcal PJI treated at two specialized orthopaedic institutions were retrospectively included from 2010 to 2017. PJI was defined by the proposed European Bone and Joint Infection Society (EBJIS) criteria. Adequate antimicrobial treatment was considered when the antibiotic was appropiate for the treatment of enterococcal bone infections (activity, dose, oral bioavailability, bone penetration). The treatment success (defined as no relapse of enteroccal infection) and clinical success(i.e. infection-free status) was evaluated and compared using Fishers exact test.
Results
We included 75 episodes with enterococcal PJI, involving 41 hip, 30 knee, 2 elbow, 1 shoulder prosthesis. The median patient age was 76 years (range, 30–90 years), 48 (64%) were female. The infection occurred perioperatively in 61 episodes (81%), haematogenously in 13 (17%) and by contiguous spread in 1 case. Sinus tract was present in 16 patients (21%), predominantly in polymicrobial compared to monomicrobial infections (13 vs. 3 episodes, p= 0.01). Preoperative serum C-reactive protein level was elevated in 63/75 patients (84%) and synovial fluid leukocyte count was increased in 25/29 patients (86%). Enterococci grew in synovial fluid in 76%, in periprosthetic tissue in 78% and in sonication fluid in 73% of patients. Predominantly, E. faecalis was identified (n=64), followed by E. faecium (n=10) and E. casseliflavus (n=1); mixed infections were diagnosed in 38 patients (51%). Two-stage prosthesis exchange was performed in 44 (59%), debridement and retention in 13 (17%), resection arthroplasty in 11 (15%) and one-stage exchange in 10 patients (13%). Of 66 patients with available follow-up data (median, 31.8 months; range, 0.3–83.3 months), the treatment success was 85% (56/66), however, clinical success was only 68% (45/66). Treatment success was similar in monomicrobial and polymicrobial infections. Adequate antimicrobial treatment was associated with significant better outcome (91% vs. 38%, p=0.002). Treatment with fosfomycin (19/20, 95%) and combination therapy (45/50, 90%) was associated with better outcome, however, did not reach statistical significance (p >0.05).
Conclusions
The treatment outcome of enterococcal PJI was high (85%), however, a second episode of PJI caused by a new pathogen was common in the later course. Adequate antimicrobial treatment was the only significant factor associated with better treatment success.
