We prospectively evaluated four different microbiological tools for diagnostics of prosthetic joint infections (PJI), and assessed their impact on the categorization of infection according to EBJIS guidelines. We compared culture, in-house real-time mPCR for A total of 341 samples (sonication fluid, tissue biopsy, synovial fluid) were collected from 32 patients with suspected PJI who underwent 56 revision surgeries at the Orthopaedic Centre University Hospital Ljubljana, between 2022 and 2024. Samples were processed using standard protocols for routine culture, followed by DNA isolation using the MagnaPure24 (Roche). All samples were tested with mPCR, and an additional ≥4 samples from each revision (244 in total) were subjected to further metagenomic analysis. Culture results were considered positive if the same microorganism was detected in ≥2 samples, ≥50 CFU/ml were present in the sonication fluid, or ≥1 sample was positive for a more virulent microorganism or if the patient had received antibiotic treatment.Aim
Methods
To date, no ultimate diagnostic gold standard for prosthetic joint infections (PJI) has been established. In recent years, next generation sequencing (NGS) has emerged as a promising new tool, especially in culture-negative samples. In this prospective study, we performed metagenomic analysis using 16S rRNA V3-V4 amplicon NGS in samples from patients with suspected PJI. A total of 257 (187 culture-negative (CN) and 70 culture-positive (CP)) prospectively collected tissues and sonication fluid from 32 patients (56 revisions) were included. 16S rRNA V3-V4 amplicons were sequenced using Illumina's MiSeq (California, USA) followed by bioinformatic analysis using nf-core/ampliseq pipeline.Aim
Methods
The aim of our study was to evaluate culture-negative prosthetic joint infections in patients who were pre-operatively evaluated as aseptic failure. For the purpose of the study we included patients planed for revision surgery for presumed aseptic failure. Intraoperatively acquired samples of periprosthetic tissue and explanted prosthesis were microbiologicaly evaluated using standard microbiologic methods and sonication. If prosthetic joint infection was discovered, additional therapy was introduced.Aim
Method
Clear differentiation between aseptic failure and prosthetic joint infection remains one of the goals of modern orthopaedic surgery. New diagnostic methods can provide more precise evaluation of the etiology of prosthetic joint failure. With the introduction of sonication an increasing number of culture-negative prosthetic joint infection were detected. The aim of our study was to evaluate culture-negative prosthetic joint infections in patients who were preoperatively evaluated as aseptic failure. For the purpose of the study we included patients planed for revision surgery for presumed aseptic failure. Intraoperatively acquired samples of periprosthetic tissue and explanted prosthesis were microbiologically evaluated using standard microbiologic methods and sonication. If prosthetic joint infection was discovered, additional therapy was introduced.Aim
Method
The treatment of orthopedic implant infections is often difficult and complex, although the chances of successful treatment with a properly selected diagnostic, surgical and antibiotic treatment protocol have recently increased significantly. Surgical treatment is a key factor in the treatment of infections of orthopedic implants, and any errors in this respect often lead to worse clinical outcomes. Surgical errors. The most important and frequent surgical errors include:
- conservative treatment of periprosthetic infections with antibiotics alone: successful treatment requires adequate surgical procedure combined with long-term antimicrobial Th that is active against biofilm microorganism. Without adequate surgical procedure just the suppression of symptoms is usually achieved, rather than eradication of the infection. - delayed surgical revision: in acute infections, early surgical intervention plays a critical role, especially by patients where retention of the prosthesis is expected. Early evacuation of postop haemathoma after primary or revision surgery is important in order to prevent the possibility of infection. It is important to take into consideration, that a postop apparently superficial surgical site infection may be indicative of deeper infection involoving the implant. - insufficient debridement during surgical revision: thorough and extensive debridement is the most critical predictor of success (removal of the haemathoma, abscess formations, fibrous membranes, sinus tracts, devitalized bone and soft tissue, removal of all cement, cement restrictors, foreign and prosthetic material; eventual exchange of modular components and liners). Finally meticulous irrigation of the op region is obligatory. - inadequate intraoperative sampling for bacteriological and histological analysis: tissue samples from the areas with the most florid inflammatory changes have to be taken and sent for bacteriological and histological examination (3–6 samples). Removed implants or parts of them have to be sent to sonication. Swab cultures have low sensitivity and should be avoided. - the importance of selecting the appropriate surgical strategy for the individual patient cannot be overemphasized: not having, following and treating patients with PJI accordingly to an algorithm that is proven and successful one usually leads to unsuccessful clinical results. We present illustrative cases with each common surcical error combined with proper solution. Treatment of PJI is a demanding procedure, the goal is a long-term pain-free functional joint, that can be achieved by eradication of the infection. For a successful clinical outcome an appropriate diagnostic, surgical and antimicrobial procedure for the individual patient has to be selected.
Clear differentiation between aseptic failure and prosthetic joint infection remains one of the goals of modern orthopaedic surgery. The development of new diagnostic methods enabled more precise evaluation of the etiology of prosthetic joint failure. With the introduction of sonication an increasing number of culture-negative prosthetic joint infection were detected. The aim of our study was to evaluate culture-negative prosthetic joint infections in patients who were preoperatively evaluated as aseptic failure. For the purpose of the study we included patients planed for revision surgery for aseptic failure. Intraoperatively acquired samples of periprosthetic tissue and explanted prosthesis were microbiologicaly evaluated using standard microbiologic methods and sonication. If prosthetic joint infection was discovered, additional therapy was introduced. Between October 2010 and April 2013 54 patients were operated (12 revision knee arthroplasty, 42 revision hip arthroplasty). 10 (18,6%) patients had positive sonication and negative periprosthetic tissue sample, 5 (9,2%) patients had positive tissue samples, but negative sonication, in 9 (16,7%) patients both tests were positive and in 30 (55,5%) patients all microbiologic tests were negative. The microbiologic isolates of sonicate fluid were in 12 cases coagulase-negative staphylococci, in 3 cases P.acnes in 3 cases mixed flora, in 1 case enterococcus and in 1 case SA. From periprosthetic tissue cultures 5 samples have yielded coagulase-negative staphylococci in 5 cases P.acnes in 2 cases mixed flora, in 1 case enterococcus and in 1 case SA were isolated. With the increasing number of patients requiring revision arthroplasty, a clear differentiation between aseptic failure and prosthetic joint infection is crucial for the optimal treatment. Sonication of explanted material is more successful in the isolation of pathogens compared to periprosthetic tissue cultures. Sonication of explanted prosthetic material is helpful in the detection of culture-negative prosthetic joint infections.
Accurate identification of pathogens is a crucial step for successful treatment of implant-associated infections. Sonication of explanted foreign material and subsequent sonicate-fluid culture is regarded to be more sensitive than conventional tissue culture. However, the duration of incubation of cultures remains controversial. The aim of our study was to evaluate diagnostic yield of prolonged 14-days incubation compared to more classical 7-days incubation. Consecutive sonicate fluid culture results from a 2-years period (2013–2015) were retrospectively analysed. All sonicate fluids were cultured aerobically, anaerobically and using blood culture system for 14 days and inspected for growth on day 1, 2, 7 and 14 days. Terminal subcultivation was performed on day 7 from broth and blood culture system for additional 7 days aerobically and anaerobically. Time of bacterial isolation was recorded. Microbiological significance was determined based on isolate quantity and concomitant growth in conventional tissue cultures. A total of 394 sonicate fluid cultures from 304 patients (8–95 years, mean age 62), 53.9% (n=164) women, were analysed. 51.0% (n=201) were from explanted osteosynthetic material, 37.6% (n=148) from hip prosthesis and 11.4% (n=45) from knee prosthesis. Overall, 57.1% (n=225) of cultures were positive. Among them, 71.1% (n=160) were monomicrobial, 21.3% bimicrobial and 7.6% (n=17) polymicrobial. In total, 312 bacterial isolates were isolated. The most frequently isolated bacteria were coagulase-negative staphylococci (CoNS) 34.6% (n=108), Staphylococcus aureus 16.4% (n=51) and Propionibacterium acnes 11.2% (n=35). Gram-negative bacteria and anaerobes represented 18.3% (n=57) and 14.4% (n=45) of isolates, respectively. Among all sonicate fluid cultures, 92.0% (n=207) were positive after 7 days while 8.0% (n=18) were positive only after prolonged 14-days incubation with P. acnes being the predominant bacteria isolated after prolonged incubation. Among all P. acnes isolates 57.1% (n=20) were isolated within 7 days and 42.9% (n=15) within 14 days. Based on microbiologic criteria, 45.7% (n=16) of them were diagnostic; 37.1% (n=13) among early isolates and 8.6% (n=3) among late isolates, difference being statistically significant (p=0.016). Prolonged 14-days incubation of sonicate fluid culture for the diagnosis of implant-associated infections offers only minor 8.0% improvement with regard to conventional 7-days incubation. The majority of P. acnes isolated after prolonged incubation are non-diagnostic using microbiologic criteria. Caution in an interpretation of significance of P. acnes isolated after 14-days incubation is warranted. However, due to a significant impact on patient management prolonged 14-days incubation is still recommended.
Introduction: In recent years the implementation of sonication in the diagnosis of orthopaedic implant infections has improved the detection of subclinical infections. With the use of sonication of removed orthopaedic material we can detect the presence of biofilm. The method has already shown encouraging results, especially in cases of preoperative antibiotic therapy. Aim: The aim of the study was to detect infections of orthopaedic material using both sonication and standard diagnostic methods, and to compare the obtained results of both methods. For the purpose of the study we sonicated all explanted material at revision surgery and cultured the obtained samples. During revision surgery soft tissue biopsies were collected and analyzed using standard microbiologic methods. The results were compared, analyzed and additional therapy was applied, if an infection of the material was proven. During the period from September 2009 to the end of March 2014 we studied 249 cases (198 patients) of revision surgery (166 cases of revision hip arthroplasty, 53 cases of revision knee arthroplasty, 13 cases of revision foot surgery, 17 cases of revision spine surgery). Of studied cases infection was proven in 20 (8,0%) cases by soft tissue biopsies only, 90 cases (36,1%) were diagnosed both by soft tissue biopsies and sonication, 45 cases (18,1%) were diagnosed only by sonication of explanted prosthetic material and in 94 cases (37,8%) all results were negative. The statistical analysis has shown statistically significant (p<0,05) improvement of infection detection using sonication. According to our experience the implementation of sonication has shown an improvement in the diagnosis of orthopaedic implant infections. Despite certain limitations, sonication should be considered in doubtful cases of revision surgery. The use of sonication should be emphasized in cases of preoperative antibiotic treatment.
