Abstract Background. The treatment of bone and joint infections (BJI) involving multi-drug resistant bacteria remains a challenge. MDR Staphylococcus epidermidis (MDRSE) clones, resistant to methicillin, clindamycin, levofloxacin, rifampicin and even linezolid, have been reported worldwide. The interest of delafloxacin (DFX), theoretically active on MRSA, remains to be evaluated with respect to MDRSE. Purpose. Our objective was to evaluate during a retrospective multicenter study the DFX minimal inhibitory concentrations (MICs) and compare its efficacy between ofloxacin-susceptible and ofloxacin-resistant S. epidermidis clinical strains involved in BJI. Methods. In this multicenter retrospective study (Reference centers from the West part of France, CRIOGO), 529 strains were collected mostly from BJI. DFX MICs were determined by using a 0.5 Mc Farland bacterial inoculum on Mueller-Hinton agar plates with gradient strips incubated for 24h at 35°C. For S. aureus, breakpoints differentiate skin and soft tissue infections from other infections. Breakpoints followed 2022 EUCAST criteria, with S. aureus values adopted for S. epidermidis. Results. Of the 529 strains collected, 355 were from prosthetic infections, 159 from synthetic infections and 15 from non-device infections. 152 strains were susceptible to ofloxacin (110 males vs 42 females) and 377 resistant (210 vs 167). As presented in Figure 1, all the ofloxacin-susceptible strains presented a DFX MIC ≤0.006mg/L. Resistant strains presented a double population distribution, with 3.7% categorized susceptible according to skin and soft tissues infections breakpoint, against 88.9% according to other breakpoint infections (0.016 or 0.25mg/L respectively). Conclusion. DFX shows excellent activity against ofloxacine-susceptible strains. Concerning the ofloxacin-resistant strains, more than 80% strains or less than 10% can be considered as DFX-susceptible depending on the breakpoints used. Further clinical studies are needed to validate the real breakpoints that must be used in MDRSE BJI, allowing a microbiological cure and a favourable clinical outcome. For any tables or figures, please contact the authors directly

Abstract. Background. Distinction between foot and ankle wound healing complications as opposed to infection is crucial for appropriate allocation of antibiotic therapy. Our aim was to evaluate the diagnostic accuracy of white cell count (WCC) and C-reactive protein (CRP) as diagnostic tools for this distinction in the non-diabetic cohort. Methods. Data were reviewed from a prospectively maintained Infectious Diseases Unit database of 216 patients admitted at Leicester University Hospitals – United Kingdom between July 2014 and February 2020 (68 months). All diabetic patients were excluded. For the infected non-diabetic included patients, we retrospectively retrieved the inflammatory markers (WCCs and CRP) at the time of presentation. Values of CRP 0–10 mg/L and WCC 4.0–11.0 ×109 /L were considered normal. Results. 25 patients met our inclusion criteria. Infections were confirmed microbiologically with positive intra-operative culture results. 7 (28%) patients with foot osteomyelitis (OM), 11 (44%) with ankle OM, 5 (20%) with ankle septic arthritis, and 2 (8%) patients with post-surgical wound infection were identified. Previous bony surgery was identified in 13 (52%) patients. 21 (84%) patients did have raised inflammatory markers while 4 (16%) patients failed to mount an inflammatory response even with subsequent debridement and removal of metalwork. CRP sensitivity was 84%, while WCC sensitivity was only 28%. Conclusion. CRP had good sensitivity, whereas WCC is a poor inflammatory marker in the detection of such cases. In presence of a clinically high level of suspicion of foot or ankle infection, a normal CRP should not rule out the diagnosis of OM

Aim. We aimed to assess the incidence and the outcome of Gram-negative prosthetic-joint infections (PJI) in 3 international tertiary hospital. Method. We included patients with Gram-negative PJI at Humanitas Clinical and Research Hospital (Milan, Italy), Centre Hospitalier Universitaire Vaudois (Lausanne, Switzerland) and Hospital Parc de Salut Mar (Barcelona, Spain) between 2014 and 2018 in a retrospective cohort. We described the treatment's success rate according to Gram-negative species and type of surgical procedure. Results. In the present cohort we have 780 PJI out of which 71 (9.1%) were caused by Gram-negative bacteria (polymicrobial infection 30%, Escherichia coli 25%, Pseudomonas aeruginosa 20%, Proteus spp. 4%, Klebsiella spp. 3%, Morganella morganii 3%, Enterobacter 3%, others 12%). Gram-negative PJI were more common in females (60%) than males (40%). Sixty percent had a hip infection, 40% a knee infection, the median age was 74 years and the median ASA score was 3. It was a chronic infection in 60% of the cases and an acute one in 40%. Two-step exchange was performed in 55%, débridement and retention (DAIR) in 30%, one-step exchange in 11% and implant removal without replacement in 4% of the patients. The overall treatment success rate was 89%. The success rate was better for two-step exchange (95%) compared to DAIR (81%) and one-step exchange (87%) (p=0.068). The median antibiotic duration was 68 days and ciprofloxacin was used in 70% of the cured patients versus in 88% of the failures (p=0.388). Infections caused by Escherichia coli were associated with a lower success rate (83%) especially compared to Pseudomonas aeruginosa (93%) and polymicrobial infections (90%) (p=0.358). Finally, the success rate was better in knee PJI compared to hip PJI (97% versus 83%, p=0.121) and in females compared to males (93% versus 82%, p=0.121). Conclusions. The treatment's success of Gram-negative PJI is comparable to reported rates for all bacteria. However, our results suggest that surgical management with two-step exchange might be useful in selected patients’ groups such as those with Escherichia coli PJI. Moreover, ciprofloxacin use seems not to improve cure rate

Staphylococcus aureus osteo-articular infections (OAI) are frequently accompanied by blood stream infections (BSI) diagnosed by positive blood culture (BC). Microbiological protocols in adults advise prolonged intravenous antibiotics and repeat BC 48-hourly in the presence of a BSI, however evidence to support the systematic employment of these guidelines in paediatric patients is lacking. We aimed to determine whether there was an increased incidence of orthopaedic and systemic complications in patients with s aureus BSI, and whether a shorter duration of intravenous antibiotics was associated with the development of complications.

Following ethical approval, the departmental surgical database was searched for patients that underwent surgery for acute OAI over a 5-year period. Patients with no sample taken for BC were excluded, as were those with other or no organisms identified from any site. Demographic and clinical data were captured, including duration of IV antibiotics and development of complications. Statistical significance was set at p<0.05.

Following exclusions, 44 patients with a median age of 85 months remained to be analysed. Thirty patients (68%) had a positive BC. A positive BC was associated with a higher rate of systemic complications (p=0.026) but not orthopaedic complications (p=0.159). Patients who had developed any complication had a significantly longer duration of IV antibiotic treatment compared to those without complications (p<0.001). The presenting CRP levels were significantly higher in patients that developed complications (p=0.004).

Patients with staphylococcal BSI in association with an OAI are at increased risk of developing systemic complications. In our cohort, a shorter duration of antibiotic use was not associated with the development of complications, which does not support the systematic use of long courses of IV antibiotics in s aureus BSI. Further research will be required to determine the ideal protocol for these patients.

Aim. National Joint Replacement Registries, which are important sources for periprosthetic joint infection (PJI) data, report an average PJI incidence ranging from 0.5 to 2.0%. Unfortunately, national registries including the Dutch Arthroplasty Register (LROI), are not specifically designed to register PJI. In the Netherlands, the LROI is a nationwide population-based registry with an overall completeness of more than 95%. 3. To ensure usability and reliability of PJI data from the LROI, it is important to evaluate the quality and completeness of these data. From 2013 onwards, eight hospitals in the South-East of the Netherlands, collected their PJI data in a detailed regional infection cohort (RIC), specifically designed for this purpose. This study aimed to determine the accuracy and completeness of PJI registration (hip and knee arthroplasty) in the LROI, by comparing the LROI with the RIC. Method. All patients registered with an acute PJI in the RIC between 2014–2018 were selected for the study and were matched with the LROI. According to the Workgroup of American Musculoskeletal Infections Society (MSIS), an acute PJI was defined as at least two phenotypically identical pathogens, isolated in cultures from at least two separate tissues, obtained from the affected peri-prosthetic tissue during the DAIR treatment (debridement, antibiotics, irrigation, and retention). Only PJI occurring within 90 days after primary hip or knee arthroplasty were included. The LROI data and completeness was based on the entered procedures and documented reason for revision infection, which was not specially based on the MSIS criteria. After checks on missing and incorrectly data, the completeness of registration in the LROI was calculated by comparing the number of registrations in the LROI with data from the RIC (gold standard). Results. Of the 639 primary total hip and knee arthroplasty with a suspected PJI registered in the RIC between 2014–2018, 352 cases met the definition of acute PJI. The overall incidence was 1%. When compared with the LROI, 164 of these cases were also registered in the LROI as PJI revision, resulting in a 53% underestimation of PJI for the LROI. Conclusions. LROI data on acute PJI shows a significant underestimation, which is comparable to scarce other literature sources. To ensure reliability and usability of national PJI data, a specifically part of the LROI has to be designed for registering PJI similar to the regional cohort

Introduction. Polymicrobial infections are expected to complicate the treatment of bone and joint infections. Septic nonunions often occur after initial open fractures, which prophylactically receive broad-spectrum antibiotics. However, no data that describes frequencies of polymicrobial infections and pathogens evident in course of the treatment of septic nonunions is published. Therefore, this study aims at investigating the frequency and pathogen types in polymicrobial infections. Methods. Surgically treated Patients with long bone septic nonunion admitted between January 2010 and March 2018 were included in the study. Following parameters were examined: age, gender, American Society of Anesthesiologists (ASA) score, body mass index (BMI), and anatomical location of the infected nonunion. Microbiological culture data, polymerase-chain-reaction results of tissue samples, sonication, and joint fluid of the initial and follow-up revision surgeries were assessed. No exclusion criteria were determined. Results. The study encompassed 42 patients with a mean age of 53.9 ± 17.7 years (range, 23 – 93). Sixteen (38.1%) patients were female. In 46.3% of the patients open fractures led to septic nonunion. Twenty-six nonunions occurred at the tibia or fibula, 11 were localized at the femur, 2 at the humerus and 3 at the forearm. Only 2 patients were assessed as ASA type 1, while 26 were ASA type 2 and 12 patients ASA type 3. Mean number of performed surgeries was 6 ± 0.67 (range 2 – 21). In 6 patients (14.3%) polymicrobial infection were evident. A change of evidenced pathogens in course of the treatment occurred in 21 patients (50%). In 16 patients (38.1%) previously detected bacteria could be evidenced by microbial testing after further revision surgery. Staphylococcus aureus was most often evident (n=34, 30.6%), followed by Enterococcus species (n=25, 22.5%) and Staphylococcus epidermidis (n=18, 16.2%). Five Staphylococcus aureus were resistant to methicillin (MRSA). In patients without polymicrobial infection or further germ detection in course of the treatment 86.4% of the infections were due to Staphylococcus species. Patients with change of detected pathogens and polymicrobial infections suffered from more enterococci infections. Infections due to streptococci and gram-negative bacteria could only be evidenced in patients with polymicrobial infection and pathogen change in course of the treatment. Conclusion. The observed difference of microbiological patterns in septic nonunion may help to facilitate adjuvant local and systemic antibiotic treatment in septic nonunion patients. Reasons for the observed difference of microbiological patterns and its influence on patient outcome have still to be elucidated

The total hip arthroplasty (THA) is an effective operation for the restoration of the hip function. The number of operations is steadily climbing and is going to reach new heights in the future. The most devastating complication is the deep infection of the joint and has to be treated with a total revision of the prostheses. The risk factors for an infection play a very important role in the preoperative assessment of the patient and for the antibiotic treatment. There are many different opinions on which risk factors are associated with the development of a deep infection in the literature. Our goal was to analyze and find the risk factors, which matter most in the clinical treatment of patients. We searched the database “PubMed” and “Embase” with the keywords: „(((hip AND infection)) AND (arthroplasty OR replacement)”. With the help of check lists and limits we extracted the most viable studies for our research. Risk factors associated with a deep infection included the BMI (Body mass index), male gender, prolonged duration of surgery, diabetes mellitus type 2, the ASA (American society of anesthesiologists) score, the Charlson score and the NNIS (National Nosocomial Infections Surveillance System) risk index score. Female gender, age and the diagnosis of rheumatoid arthritis were not associated with deep infections. Patients with risk factors should be assessed preoperatively and receive an appropriate prophylactic antibiotic treatment, to reduce the risk of a deep infection. With the reduction of their weight and adjustment of the diabetes, patients can reduce the risk for infection by their own. Total hip replacement is still a safe and effective operation and thus should not be withheld from patients

Over 300,000 total hip arthroplasties (THA) are performed annually in the USA. Surgical Site Infections (SSI) are one of the most common complications and are associated with increased morbidity, mortality and cost. Risk factors for SSI include obesity, diabetes and smoking, but few studies have reported on the predictive value of pre-operative blood markers for SSI. The purpose of this study was to create a clinical prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of THA based on commonly ordered pre-operative lab markers and using data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. All adult patients undergoing an elective unilateral THA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was used to determine coefficients, with manual stepwise reduction. Receiver Operating Characteristic (ROC) curves were also graphed. The SSI prediction model included the following covariates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphate, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. Since the data met logistic assumption requirements, bootstrap estimation was used to measure internal validity. The area under the ROC curve for final derivations along with McFadden's R-squared were utilized to compare prediction models. A total of 130,619 patients were included with the median age of patients at time of THA was 67 years (mean=66.6+11.6 years) with 44.8% (n=58,757) being male. A total of 1,561 (1.20%) patients had a superficial or deep SSI (overall SSI). Of all SSI, 45.1% (n=704) had a deep SSI and 55.4% (n=865) had a superficial SSI. The incidence of SSI occurring annually decreased from 1.44% in 2011 to 1.16% in 2016. Area under the ROC curve for the SSI prediction model was 0.79 and 0.78 for deep and superficial SSI, respectively and 0.71 for overall SSI. CHF had the largest effect size (Odds Ratio(OR)=2.88, 95% Confidence Interval (95%CI): 1.56 – 5.32) for overall SSI risk. Albumin (OR=0.44, 95% CI: 0.37 – 0.52, OR=0.31, 95% CI: 0.25 – 0.39, OR=0.48, 95% CI: 0.41 – 0.58) and sodium (OR=0.95, 95% CI: 0.93 – 0.97, OR=0.94, 95% CI: 0.91 – 0.97, OR=0.95, 95% CI: 0.93 – 0.98) levels were consistently significant in all clinical prediction models for superficial, deep and overall SSI, respectively. In terms of pre-operative blood markers, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI. In this large NSQIP database study, we were able to create an SSI prediction model and identify risk factors for predicting acute superficial, deep and overall SSI after THA. To our knowledge, this is the first clinical model whereby pre-operative hyponatremia (in addition to hypoalbuminemia) levels have been predictive of SSI after THA. Although the model remains without external validation, it is a vital starting point for developing a risk prediction model for SSI and can help physicians mitigate risk factors for acute SSI post THA

Total knee arthroplasty (TKA) is the most commonly performed elective orthopaedic procedure. With an increasingly aging population, the number of TKAs performed is expected to be ∼2,900 per 100,000 by 2050. Surgical Site Infections (SSI) after TKA can have significant morbidity and mortality. The purpose of this study was to construct a risk prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of a TKA based on commonly ordered pre-operative blood markers and using audited administrative data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. All adult patients undergoing an elective unilateral TKA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was conducted to estimate coefficients, with manual stepwise reduction to construct models. Bootstrap estimation was administered to measure internal validity. The SSI prediction model included the following co-variates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphatase, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. To compare clinical models, areas under the receiver operating characteristic (ROC) curves and McFadden's R-squared values were reported. The total number of patients undergoing TKA were 210,524 with a median age of 67 years (mean age of 66.6 + 9.6 years) and the majority being females (61.9%, N=130,314). A total of 1,674 patients (0.8%) had a SSI within 30 days of the index TKA, of which N=546 patients (33.2%) had a deep SSI and N=1,128 patients (67.4%) had a superficial SSI. The annual incidence rate of overall SSI decreased from 1.60% in 2011 to 0.68% in 2016. The final risk prediction model for SSI contained, smoking (OR=1.69, 95% CI: 1.31 – 2.18), previous/current steroid use (OR=1.66, 95% CI: 1.23 – 2.23), as well as the pre-operative lab markers, albumin (OR=0.46, 95% CI: 0.37 – 0.56), blood urea nitrogen (BUN, OR=1.01, 95% CI: 1 – 1.02), international normalized ratio (INR, OR=1.22, 95% CI:1.05 – 1.41), and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98;). Area under the ROC curve for the final model of overall SSI was 0.64. Models for deep and superficial SSI had ROC areas of 0.68 and 0.63, respectively. Albumin (OR=0.46, 95% CI: 0.37 – 0.56, OR=0.33, 95% CI: 0.27 – 0.40, OR=0.75, 95% CI: 0.59 – 0.95) and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98, OR=0.96, 95% CI: 0.93 – 0.99, OR=0.97, 95% CI: 0.96 – 0.99) levels were consistently significant in all prediction models for superficial, deep and overall SSI, respectively. Overall, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI. To our knowledge, this is the first prediction model for acute SSI post TKA whereby hyponatremia (and hypoalbuminemia) are predictive of SSI. This prediction model can help fill an important gap for predicting risk factors for SSI after TKA and can help physicians better optimize patients prior to TKA

Aim. Diagnosing Fracture-Related Infections (FRI) is challenging. White blood cell (WBC) scintigraphy is considered the best nuclear imaging technique to diagnose FRI; a recent study by our group found a diagnostic accuracy of 92%. However, many centers use . 18. F-fluorodeoxyglucose positron emission tomography/computed tomography (. 18. F-FDG-PET/CT) which has several logistic advantages. Whether . 18. F-FDG-PET/CT has better diagnostic performance than white blood cell (WBC) scintigraphy is uncertain. Therefore, we aimed: 1) to determine the diagnostic performance of . 18. F-FDG-PET/CT for diagnosing FRI (defined as infection following an open fracture or fracture surgery) and 2) to determine cut-off values of standardized uptake values (SUV) that result in optimal diagnostic performance. Method. This retrospective cohort study included all consecutive patients who received . 18. F-FDG-PET/CT to diagnose FRI in two level 1 trauma centers. Baseline demographic- and surgical characteristics were retrospectively reviewed. The reference standard consisted of at least 2 representative microbiological culture results or the presence or absence of clinical confirmatory FRI signs in at least 6 months of clinical follow-up. A nuclear medicine specialist, blinded to the reference standard, re-reviewed all scans. Additionally, SUVs were measured using the “European Association of Nuclear Medicine Research Ltd. (EARL)” reconstructed . 18. F-FDG-PET/CT scans. Volume of interests were drawn around the suspected- and corresponding contralateral area to obtain the absolute values (SUVmax) and the ratio between suspected and contralateral area (SUVratio). Diagnostic accuracy of the re-reviewed scans was calculated (sensitivity and specificity). Additionally, diagnostic characteristics of the SUV measurements were plotted in the area under the receiver operating characteristics curve (AUROC). The sensitivity and specificity at the optimal threshold was deducted from the AUROC with the Q-point method. Results. 158 . 18. F-FDG-PET/CTs were included. Mean age was 46.2 years, 71.5% was male. Most cases (56.3%) were tibial shaft- or ankle fractures. Sixty patients (38.0%) had FRI. The sensitivity and specificity of the FDG-PET/CT scan was 70.0% (95% CI 56.8–81.2) and 79.6% (95% CI 70.3–87.1) respectively. Diagnostic accuracy was 76.0% (95% CI 68.5–82.4). AUROCs of SUVmax and SUVratio were 0.80 (95% CI 0.73–0.87) and 0.73 (95% CI 0.64–0.81), respectively. The optimal SUVmax threshold of 4.2 resulted in 80.0% sensitivity and 71.3% specificity, while an SUVratio of 2.9 resulted in 58.3% sensitivity and 80.9% specificity. Conclusions. The . 18. F-FDG-PET/CT has a sensitivity of 70.0%, specificity of 79.6% and a diagnostic accuracy of 76.0%. This makes . 18. F-FDG-PET/CT less accurate than WBC scintigraphy in diagnosing FRI, although adding SUV measurements may possibly increase its diagnostic accuracy

There is currently no consensus on the use of suppressive antibiotic therapy (SAT) in prosthetic joint infections (PJI) (1). We describe herein the experience of a French Reference Centre for Complex Osteo-Articular Infections on use of oral cyclines (doxycline and minocycline) for SAT. A retrospective analysis was performed on consecutive patients with PJI who received oral cyclines (doxycycline or minocycline) for SAT between January 2006 and June 2014. All patients had surgical management, followed by systemic antibiotic treatment and SAT instauration thereafter. Remission was defined as an asymptomatic patient with a functioning prosthesis. Seventy-nine patients with a mean age of 63.8 ± 16.8 years were included. Sixteen patients (20%) had neoplasia, 9 (11%) diabetes mellitus, 10 (13%) rheumatoid arthritis, and 6 patients (8%) were receiving corticosteroids or chemotherapy. There were 37 knee (47%), 36 hip (46%), 4 elbow (5%), and 2 shoulder (3%) infections, with a mean delay from implantation of 7.37 ± 6.94 months (range 1–27). Surgical management consisted in debridement and implant retention for 60 patients (76%), or in implant exchange for 19 patients (24%). Main pathogens were coagulase-negative staphylococci (37%) and Staphylococcus aureus (41%); 23 patients had polymicrobial infection (29%). The most frequent initial antibiotic regimens debuted before SAT were rifampicin combinations (70%). Mean duration of curative antibiotic therapy was 103 ± 75 days. Indications of SAT were (i) patients unsuitable for or refusing further surgery (n=23), suboptimal (ii) surgery (n=26) or (iii) curative antibiotic therapy (n=11), (iv) complex orthopaedic surgery (n=11), and (v) immunosuppressive status (n=8). Seventy-three patients received doxycycline and 6 patients received minocycline as SAT (n=48). Mean SAT duration was 625± 536 days (range 30–2900), with a mean follow-up of 765 ± 572 days. Adverse events were reported in 13 patients (16%), leading to SAT discontinuation in 5 (6%). During follow-up, 59 patients were considered in remission (75%), and 20 failed including 13 relapses (16%) and 7 reinfections (9%). Among failure patients, 10 pathogens resistant to doxy/minocycline were identified, including 5 with acquisition of cycline resistance. In our study, SAT with cyclines is associated to a 75% remission rate, with an acceptable tolerability. Further studies are warranted to determine ideal regimens and optimal duration of SAT. We would like to thank Dron Hospital and Lille University Hospital medical teams. The authors declare that there are no conflicts of interest

Aim. Data of optimal management of infections after internal fixation (IIF) is scarce and long-term follow-up results often lack. We analyzed characteristics of infections after intramedullary (IIIF) and extramedullary long bone fixation (IEIF) and evaluated their infection and functional outcome. Method. Consecutive patients with IIF diagnosed at our institution from 01/2010-10/2017 were retrospectively included. Infection was defined as visible purulence, sinus tract, microbial growth in ≥2 independent samples or positive histopathology. The outcome was compared before and after implementation of a comprehensive surgical and antimicrobial treatment algorithm in 04/2013. Results. Of 127 patients, infection involved lower extremity in 111 patients (87%). Median age was 53 years (range, 19–89 years), 70% were men. Fixation was performed with intramedullary nail in 47 (37%) and with extramedullary osteosynthesis (plates, screws, pins) in 80 patients (63%). At infection diagnosis, the implant was in situ in 96 patients (76%), whereas 31 patients (24%) had residual osteomyelitis after implant removal. The time from bone fixation to infection was longer in IIIF than IEIF (25 vs. 7 months, p=0.027). Pain was reported in 55 patients (43%) and local infection signs in 96 patients (75%), including sinus tract in 46 patients, more commonly reported after IIIF than IEIF (49% vs. 29%, p=0.035). Infections were monomicrobial in 85 (67%), polymicrobial in 18 (14%) and culture-negative in 23 patients (18%). Most common pathogens were S. aureus (43%), coagulase-negative staphylococci (28%) and gram-negative rods (22%). Débridement (with device retention, if present) was performed in 40, device removal in 43, one-stage exchange in 16 and two-stage exchange in 20 patients. One patient had no surgery and 7 patients underwent limb amputation. 43 patients (34%) were treated before implementation of the interdisciplinary treatment concept and 84 patients (66%) afterwards. Among 111 patients with available follow-up (median, 5.2 months; range, 0.2–86 months), in 78 cases (70%) infection eradication was achieved (similar in IIIF and IEIF). However, overall infection and functional outcome was only 48% (53 patients). After implementation of the treatment algorithm, the infection outcome improved from 56% to 79% (p=0.03) and the overall success from 33% to 56% (p=0.016). Conclusions. Approximately half of infections after IIF failed in terms of infection eradication or restoration of function. After implementation of standardized surgical and antibiotic treatment concept, infection and functional outcome improved significantly. No significant differences between IIIF and IEIF was observed in terms of infection and functional success

Aim

Treatment recommendations for periprosthetic joint infections (PJI) include surgical debridement, antibiotic therapy or staged revision. In surgical related foot and ankle infections (SR-FAI), implant removal will lead to instability. Debridement is difficult because the implant is outside the joint. Recommendations regarding PJI treatment can therefore not be extrapolated to the treatment of SR-FAI.

Aim

Diagnosing periprosthetic joint infections (PJI) can be very challenging, especially infections caused by low virulence microorganisms. No single test with a 100% accuracy is available yet. Hence, different infection definitions were introduced to improve the diagnostic confidence and quality of research articles. Due to constant developments in this field, infection definitions are adopted continuously. The aim of our study was to find the most sensitive currently available infection definition among three currently used criteria (International Consensus Meeting – criteria 2018 (ICM), Infectious Diseases Society of America - criteria 2013 (IDSA), and European Bone and Joint Infection Society – criteria 2021 (EBJIS)) for the diagnosis of PJI.

The diagnosis of infection following shoulder arthroplasty is notoriously difficult. The prevalence of prosthetic shoulder infection after arthroplasty ranges from 3.9 – 15.4% and the most common infective organism is Cutibacterium acnes. Current preoperative diagnostic tests fail to provide a reliable means of diagnosis including WBC, ESR, CRP and joint aspiration. Fluoroscopic-guided percutaneous synovial biopsy (PSB) has previously been reported in the context of a pilot study and demonstrated promising results. The purpose of this study was to determine the diagnostic accuracy of percutaneous synovial biopsy compared with open culture results (gold standard).

This was a multicenter prospective cohort study involving four sites and 98 patients who underwent revision shoulder arthroplasty. The cohort was 60% female with a mean age was 65 years (range 36-83 years). Enrollment occurred between June 2014 and November 2021. Pre-operative fluoroscopy-guided synovial biopsies were carried out by musculoskeletal radiologists prior to revision surgery. A minimum of five synovial capsular tissue biopsies were obtained from five separate regions in the shoulder. Revision shoulder arthroplasty was performed by fellowship-trained shoulder surgeons. Intraoperative tissue samples were taken from five regions of the joint capsule during revision surgery.

Of 98 patients who underwent revision surgery, 71 patients underwent both the synovial biopsy and open biopsy at time of revision surgery. Nineteen percent had positive infection based on PSB, and 22% had confirmed culture positive infections based on intra-operative tissue sampling. The diagnostic accuracy of PSB compared with open biopsy results were as follows: sensitivity 0.37 (95%CI 0.13-0.61), specificity 0.81 (95%CI 0.7-0.91), positive predictive value 0.37 (95%CI 0.13 – 0.61), negative predictive value 0.81 (95%CI 0.70-0.91), positive likelihood ratio 1.98 and negative likelihood ratio 0.77.

A patient with a positive pre-operative PSB undergoing revision surgery had an 37% probability of having true positive infection. A patient with a negative pre-operative PSB has an 81% chance of being infection-free. PSB appears to be of value mainly in ruling out the presence of peri-prosthetic infection. However, poor likelihood ratios suggest that other ancillary tests are required in the pre-operative workup of the potentially infected patient.

Aim

The most frequent mechanical failure in the osteosynthesis of intertrochanteric fractures is the cut-out. Fracture pattern, reduction quality, tip-apex distance or the position of the cervico-cephalic screw are some of the factors that have been associated with higher cut-out rates. To date, it has not been established whether underlying bacterial colonization or concomitant infection may be the cause of osteosynthesis failure in proximal femur fractures (PFF). The primary objective of this study is to assess the incidence of infection in patients with cut-out after PFF osteosynthesis.

Aim

Smoking is known to impair wound healing and to increase the risk of peri-operative adverse events and is associated with orthopaedic infection and fracture non-union. Understanding the magnitude of the causal effect on orthopaedic infection recurrence may improve pre-operative patient counselling.

Aim

Sepsis is a life-threatening complication of periprosthetic joint infections (PJI) that requires early and effective therapy. This study aims to investigate the epidemiology, associated risk factors, and outcome of sepsis in the context of periprosthetic joint infections (PJI).

Aim

Dalbavancin is a lipoglycopeptide with a half-life of 14 days (range 6.1 to 18.4), significantly longer than other antimicrobials, which avoids the need for daily antibiotic dosing. This multi-centre observational study aims to describe the use of dalbavancin to facilitate discharge in treating bone and joint infections.

Aim

Fungal periprosthetic joint infections are difficult to treat and often associated with a limited outcome for patients. Candida species account for approximately 90% of all fungal infections. In vivo biofilm models play major role to study biofilm development, morphology, and regulatory molecules for bacteria. However, in vivo modeling of biofilm-associated fungi models are very rare. Furthermore, due to ethical restrictions, mammalian models are replaced with other alternative models in basic research. Recently, we have developed insect infection model G. mellonella larvae to study implant associated biofilm infections with bacteria. This model organism was not used for fungi biofilm infection yet. Thus, we aimed to establish G. mellonella as in vivo model to study fungal implant infections using Candida albicans as model organism and to test anti-fungal medication.