Treatment of chronic prosthetic joint infection (PJI) combines exchange arthroplasty and effective antibiotic therapy. Minocycline, a cyclin antibiotic, is naturally effective against methicillin-resistant staphylococci. We use this antibiotic since many years in combination with vancomycin for the treatment of multi-drug resistant staphylococcal bone and joint infections. The aim of this study is to analyze the outcome of patients treated with combination antibiotic therapy including minocycline for the treatment of chronic methicillin-resistant staphylococcal PJI. We conducted a cohort study between 2004 and 2014 in our referral center for bone and joint infections. Data were extracted from the prospective database. All the patients receiving an initial combination therapy including at least 4 weeks of minocycline, given orally, and another IV antibiotic, usually high-dose continuous IV vancomycin, for chronic MR staphylococcal PJI and who underwent one or two stage exchange arthroplasty, were included. They were followed prospectively for at least 2 years.Aim
Method
The diagnosis of prosthetic joint infections (PJI) represents a critical challenge for orthopedic surgeons and infectious disease specialists. The diagnosis of PJI is often delayed because non-invasive assays lack sensitivity and specificity. A novel multiplex immunoassay detecting antibodies against Staphylococci, Propionibacteria and Streptococcus agalactiae was developed and its performance evaluated in a prospective, multicenter, non-interventional study. The Luminex-based assay measures serum IgG against a proprietary panel of recombinant purified antigens from Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae and Propionibacterium acnes. Patients undergoing revision arthroplasty were included over a 2-year period (from 2012 up to 2014) in two French reference centers in compliance with IRB and French regulations. PJI cases were defined microbiologically (≥2 intraoperative samples yielding the same microorganism) for confrontation of microbiological and immunoassay data. 455 patients were eligible for study analyses. 149 patients (32.7%) were found to be infected. Among the most frequent infecting species recovered were S. aureus (30%), S. epidermidis (26%), P. acnes (9%), S. lugdunensis (6%), and S. agalactiae (4%). The sensitivity and specificity values of the test were, respectively, 75.9% (63/83) and 82.2% (180/219) for staphylococci (S. aureus, S. epidermidis, S. lugdunensis), 38.5% (5/13) and 81.9% (190/232) for P. acnes, and 66.7% (4/6) and 92.4% (208/225) for S. agalactiae. Interestingly, all cases (9/9) involving S. lugdunensis were detected by the test and the sensitivity for S. epidermidis reached 79.4% in patients more than three months after joint replacement. In a similar fashion, 89.5% (17/19) in the subpopulation with elevated inflammatory markers (ESR>30 and CRP>10). The assay correctly identified 67% of the microbiologically positive patients that were negative by ESR or CRP screening. This novel multiplex serological test allows the rapid and non-invasive diagnosis of the most frequent PJI pathogens, showing a good correlation with microbiological culture. and appears to be a new promising tool in the management of PJI, adding sensitivity to the current serological assays and enhancing the management of patients with pauci-inflammatory PJI.
