The purpose of this study was to evaluate the infection-free outcome of patients underwent revision of total joint arthroplasty (TJA) for presumed aseptic causes, with positive intra-operative cultures. A retrospective cohort study was assembled with 130 patients undergoing revision knee (21 cases) or hip arthroplasty (109 cases) for presumed aseptic causes. For all patients five to seven separate intra-operative cultures were obtained and prosthesis sonication was done. Patients were diagnosed with a previously unsuspected prosthetic joint infection (PJI) if two or more cultures were positive or a positive prosthesis sonication. Data were reviewed for demographic details, preoperative laboratory results and culture results. The endpoint was infection-free implant survival at 24 months.Aims
Patients and Methods
Diagnosis of periprosthetic joint infection (PJI) is challenging given the limitations of available diagnostic tests. Recently, several studies have shown a role of the long pentraxin PTX3 as a biomarker in inflammatory diseases and infections. This single-center prospective diagnostic study evaluated the diagnostic ability of synovial fluid and serum PTX3 for the infection of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Consecutive patients undergoing revision surgery for painful THA or TKA were enrolled. Patients with antibiotic therapy suspended for less than 2 weeks prior to surgery and patients eligible for metal-on-metal implant revision or spacer removal and prosthesis re-implantation were excluded. Quantitative assessment of synovial fluid and serum PTX3 was performed with ELISA method. Musculoskeletal Infection Society (MSIS) criteria were used as reference standard for diagnosis of PJI. Continuous data values were compared for statistical significance with univariate unpaired, 2-tailed Student's t-tests. Receiver operating characteristic (ROC) curve analyses was performed to assess the ability of serum and synovial fluid PTX3 concentration to determine the presence of PJI. Youden's J statistic was used to determine optimum threshold values for the diagnosis of infection. Sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative (LR-) likelihood ratio, area under the ROC curve (AUC) were calculated.Aim
Method
Diagnosis of periprosthetic joint infection (PJI) is still challenging due to limitations of available diagnostic tests. Many efforts are ongoing to find out novel methods for PJI diagnosis. Recently, several studies have shown a role of the long pentraxin PTX3 as a biomarker in inflammatory diseases and infections. This pilot diagnostic study evaluated the diagnostic ability of synovial fluid and serum PTX3 for the infection of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Consecutive patients undergoing revision surgery for painful THA or TKA were enrolled. Patients with antibiotic therapy suspended for less than 2 weeks prior to surgery and patients eligible for spacer removal and prosthesis re-implantation were excluded. Quantitative assessment of synovial fluid and serum PTX3 was performed with ELISA method. Musculoskeletal Infection Society (MSIS) criteria were used as reference standard for diagnosis of PJI. Continuous data values were compared for statistical significance with univariate unpaired, 2-tailed Student's t-tests. Receiver operating characteristic (ROC) curve analyses was performed to assess the ability of serum and synovial fluid PTX3 concentration to determine the presence of PJI. Youden's J statistic was used to determine optimum threshold values for the diagnosis of infection. Sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values, positive (LR+) and negative (LR-) likelihood ratio, area under the ROC curve (AUC) were calculated.Aim
Method
Almost any kind of bacteria can be involved in prosthetic joint infections (PJI). In 2014 we collected data on 3 patients presenting with hip or knee pain and radiological signs of prosthetic joint mobilization without any other clinical or biochemical suspect of infection. Interestingly, in all cases we isolated bacteria very rarely involved in human infections: Cupriavidus pauculus, Ralstonia paucula and Neisseria flavescens. Both Cupriavidus pauculus and Ralstonia paucula are Gram negative environmental bacteria which can contaminate water (tap, pool and mineral) and have been isolated from a variety of human clinical sources including blood, wounds, sputum, urine, eye, throat and peritoneal fluid, as non pathogenic flora. In such two patients we were able to cure the infection with quinolones (both strains were sensible). Neisseria species are Gram-negative bacteria included among the proteobacteria. Neisseria flavescens is often found in the upper respiratory tract and oropharynx of humans, rarely associated with infectious process (necrotizing pneumonia and empyema). In this last patient we successfully used piperacillin-tazobactam i.v. during hospitalization and shifted to amoxicillin-clavulanate per os at discharge. In conclusion, any bacteria can induce PJI: in some cases pre-operative blood tests are normal and therefore useless. We need new tests to overcome this diagnostic problem (such as alpha-defensin) and we must check on rare bacteria prolonging incubation to a more extended period of time (as in Propionebacterium acnes or Mycobacterium spp) and/or sending samples to specialized laboratories. We thank all the medical and nurse staff of Prosthetic Joint Replacement Unit of Orthopaedic Center, Humanitas Research Hospital
