Bacteriophages are remerging as alternative and adjunctive therapy for fracture-related infection (FRI). However, current administration protocols involve prolonged retention of a percutaneous draining tube with potential risk of developing superinfection. In this study, we applied a cocktail of Two evolved bacteriophages (MRSA-R14 and COL-R23) with improved antibiofilm activity against a clinical isolate (MRSA3) were tested in combination with vancomycin and a carboxymethylcellulose (CMC) hydrogel Aim
Method
Antimicrobial suppression has shown to significantly improve treatment success of streptococcal periprosthetic joint infection (PJI) compared to 12-week standard antimicrobial therapy, however, only short-term follow-up was investigated. In this study we assessed the impact of suppression on the long-term outcome of streptococcal PJI. Consecutive patients with streptococcal PJI (defined by EBJIS criteria) treated 2009–2021 were prospectively included and allocated into standard and suppression (> 6 months) treatment group. Infection-free survival was assessed with Kaplan-Meier-method and compared between the groups with log rank test. Rates of infection-free, streptococcal infection-free and relapse-free status as well as tolerability of suppression were assessed.Aim
Method
Antibiotics have limited activity in the treatment of multidrug-resistant or chronic biofilm-associated infections, in particular when implants cannot be removed. Lytic bacteriophages can rapidly and selectively kill bacteria, and can be combined with antibiotics. However, clinical experience in patients with surgical infections is limited. We investigated the outcome and safety of local application of bacteriophages in addition to antimicrobial therapy. 8 patients (2 female and 6 male) with complex orthopedic and cardiovascular infections were included, in whom standard treatment was not feasible or impossible. The treatment was performed in agreement with the Article 37 of the Declaration of Helsinki. Commercial or individually prepared bacteriophages were provided by ELIAVA Institute in Tbilisi, Georgia. Bacteriophages were applied during surgery and continued through drains placed during surgery three times per day for the following 5–14 days. Follow-up ranged from 1 to 28 months.Aim
Method
Synovial fluid D-lactate may be useful for diagnosing septic arthritis (SA) as this biomarker is almost exclusively produced by bacteria. We evaluated the performance of synovial fluid D-lactate and determined its optimal cut-off value for diagnosing SA. Consecutive patients with suspicion of septic arthritis were prospectively included. They underwent joint aspiration and synovial fluid was collected for culture, leukocyte count and D-lactate concentration (by spectrophotometry). Youden's J statistic was used for determining optimal D-lactate cut-off value on the receiver operating characteristic (ROC) curve by maximizing sensitivity and specificity.Aim
Method
The rise of multidrug-resistant bacteria and the decreasing efficacy of antibiotic therapy in successfully treating biofilm-associated infections are prompting the exploration of alternative treatment options. This study investigates the efficacy of different bioactive glass (BAG) formulations - alone or combined with vancomycin - to eradicate biofilm. Further, we study the influence of BAG on pH and osmotic pressure as important factors limiting bacterial growth. Different BAG-S53P4 formulations were used for this study, including (a) BAG-powder (<45 μm), (b) BAG-granules (500–800 μm), (c) a cone-shaped BAG-scaffold and (d) two kinds of BAG-putty containing granules, with no powder (putty-A) or with additional powder (putty-B), and a synthetic binder. Inert glass beads were included as control. All formulations were tested in a concentration of 1750 g/ml in Müller-Hinton-Broth. Targeted bacteria included methicillin-resistant To investigate the antibiofilm effect of BAG alone or combined with vancomycin, 3 hour-old MRSA or MRSE biofilms were formed on porous glass beads and exposed to BAG ± vancomycin for 24h, 72h and 168h. After co-incubation, biofilm-beads were deep-washed in phosphate-buffered saline and placed in glass vials containing fresh medium. Recovering biofilm bacteria were detected by measuring growth-related heat production at 37°C for 24h by isothermal microcalorimetry. Changes in pH and osmotic pressure over time were assessed after co-incubation of each BAG formulation in Müller-Hinton-Broth for 0h, 24h, 72h and 168h.Aim
Method
Quadrupled hamstring anterior cruciate ligament plasties (4xHp) have been described as having a higher risk of infection than bone patellar tendon bone plasties (BPTBp). There are 2 theories that might explain this phenomenon. One is the presence of sutures in a 4xHp that could act as a foreign body, The other is the more complex preparation of a 4xHp that might lead to higher contamination rates during the process. The objective of the present study was to evaluate the formation of biofilm in these plasties and to compare it between a 4xHp and a BPTBp. The hypothesis was that the presence of sutures in 4xHp would increase the amount of biofilm present in them in comparison to BPTBp. A descriptive in vitro study was conducted. One 4xHp and one BPTBp were prepared. They were subsequently divided into 8 fragments. Three of them were reserved for negative control, and the rest were contaminated with a strain of S. Epidermidis (ATCC 35984) 10–5. Finally, a quantitative analysis was carried out by means of microcalorimetry and sonication with plating. Additionally, a qualitative analysis was carried out by means of electron microscopy.Aim
Method
Rifampicin plays an important role in the treatment of staphylococcal prosthetic joint infection, as rifampicin-containing combinations have shown a high efficacy against Four rifampicin-resistant MRSA strains were used in this study. The MIC for all tested antibiotics was determined by Etest. Biofilms were formed on porous glass beads for 24h and exposed to Sb1 (107 PFU/mL) for 24h followed by exposure to antibiotic for 24h. Viability of bacteria after antimicrobial treatment was detected by beads sonication and plating of the sonication fluids. The minimum biofilm eradication concentration (MBEC) was defined as the lowest concentration of antibiotic required to kill all cells resulting in the appearance of no colony after plating of the sonication fluid (detection limit <20 CFU/mL). The synergistic effects were observed when Sb1 combined with antibiotics used at least 2 log-reduction lower concentrations.Aim
Method
We evaluated the efficacy and safety of treatment regimens in a pathogen and surgery specific mode according to a standardized algorithm for the treatment of periprosthetic joint infection (PJI) based on combinations with 15g/d intravenous fosfomycin followed by oral antibiotics for totally 12 weeks. Consecutive patients with PJI caused by at least one of the following isolates were prospectively included: staphylococci (MIC ≤32 mg/l), streptococci (MIC ≤128 mg/l), enterococci (MIC ≤128 mg/l), Enterobacteriaceae (MIC ≤32 mg/l) and Pseudomonas spp. (MIC ≤128 mg/l). PJI was defined by the proposed European Bone and Joint Infection Society (EBJIS) criteria. Follow up with clinical (joint function and quality of life scores), laboratory and radiological evaluation at 3, 12 and 24 months after last surgery is performed. Infection outcome was assessed as the proportion of infection-free patients. The probability of infection-free survival was estimated using the Kaplan-Meier survival method.Aim
Method
To investigate the ability of the bacteriophage Sb-1 to treat and prevent implant-associated infections due to methicillin-resistant Staphylococcus aureus (MRSA) in The stability of Sb-1 in Aim
Method
To evaluate the analytical performance of synovial fluid D-lactate test for the diagnosis of PJI. Consecutive patients undergoing diagnostic joint aspiration of prosthetic joint were prospectively included. PJI was diagnosed according to the proposed European Bone and Joint Infection Society (EBJIS) definition criteria. Synovial fluid was collected for culture, D-lactate measurement (by spectrophotometry, λ = 570 nm) and leukocyte count and differential (by flow cytometry). The receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of D-lactate and leukocyte count.Aim
Method
Ciprofloxacin is recommended as anti-biofilm therapy for gram-negative periprosthetic joint infection. With ciprofloxacin monotherapy, resistance in gram-negative bacteria was observed. Therefore, we evaluated
Aim
Method
Surgical and antimicrobial treatment of periprosthetic joint infections (PJI) depends largely on the causative pathogen. We assessed the pathogen detection rates and the concordance of preoperative synovial fluid culture and culture of intraoperative samples harvested during revision surgery in patients with PJI. Culture-positive PJI cases treated at our institution from 02/2011 to 07/2018, for which culture results from preoperative (synovial fluid) and intraoperative samples (periprosthetic tissue, synovial or sonication fluid) were available, were retrospectively assessed. For organisms belonging to the resident skin flora (coagulase-negative staphylococci, cutibacteria and corynebacteria) significant growth was considered, if the identical pathogen grew in ≥2 samples or >50 cfu/ml sonication fluid. For other pathogens (S. aureus, streptococci, enterococci, fungi and gram-negative rods) or patients under antimicrobials, any growth was considered positive. We determined the pathogen detection rate in preoperative and intraoperative cultures and compared it in different subgroups using Fisher's exact test. Furthermore, we assessed the concordance of preoperative and intraoperative cultures.Aim
Method
Most orthopedic infections are due to the microbial colonization of abiotic surfaces, which evolves into biofilm formation. Within biofilms, persisters constitute a microbial subpopulation of cells characterized by a lower metabolic-activity, being phenotipically tolerant to high concentrations of antibiotics. Due to their extreme tolerance, persisters may cause relapses upon treatment discontinuation, leading to infection recalcitrance hindering the bony tissue regeneration. Using isothermal microcalorimetry (IMC), we aimed to evaluate A 24h-old MRSA ATCC 43300 biofilm was exposed to 1024 µg/ml VAN for 24h. Metabolism-related heat of biofilm-embedded cells, either during or after VAN-treatment, was monitored in real-time by IMC for 24 or 48h, respectively. To evaluate the presence of VAN-derived “persisters” after antibiotic treatment, beads were sonicated and detached free-floating bacteria were further challenged with 100xMIC VAN (100 µg/ml) in PBS+1% Cation Adjusted Mueller Hinton Broth (CAMHB).. Suspensions were plated for colony counting. The resumption of persister cells' normal growth was analysed by IMC on dislodged trated cells for 15h in CAMHB. Activity of 16 µg/ml daptomycin was assessed against persister cells by colony counting.Aim
Method
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. 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.Aim
Method
Virulent bacteriophages are known to be an effective therapy against various human bacterial infections. The aims of the study are to evaluate i) the killing activity of an antistaphylococcal phage lysate (ASPL), available in the Czech Republic for topical application, against The susceptibility of 25 MRSA and 18 methicillin-sensitive Sa (MSSA) strains to the ASPL was evaluated by spot assay. In addition, susceptibility of four laboratory MRSA strains, including ATCC 43300, ATCC 33591, Mu3 (MRSA/hetero vancomycin intermediate resistant Sa) and Mu50 (MRSA/vancomycin-resistant Sa) was also tested. The activity of ASPL against planktonic and biofilm-embedded MRSA ATCC 43300 was evaluated in real-time by isothermal microcalorimetry. The minimum heat inhibitory concentrations (MHIC) was defined as the lowest antimicrobial concentration leading to the lack of heat flow production after 24h for both planktonic and biofilm-embedded cells. The viability of bacterial cells was assessed by plating and colony counting. The minimum bactericidal concentration (MBC) was defined as the lowest antimicrobial concentration leading the reduction of 3 log CFU compared to the untreated control.Aim
Method
To compare the performance of sonication and chemical methods (EDTA and DTT) for biofilm removal from artificial surface. In vitro a mature biofilms of Aim
Method
Aim of this study was to evaluate the ability of Sb-1 to enhance the antibiotic activity (tested in combination) degrading the biofilm matrix (impairing the freely diffusion of antimicrobials) and specifically targeting “persister” cells (biofilm sub-population tolerant to most antibiotics and responsible for the infection recalcitrance) of methicillin-resistant MRSA ATCC 43300 24h-old biofilm was treated for 18h with Sb-1 titers (from 104 to 106 pfu/ml). Biofilm matrix was evaluated by confocal laser scanning microscopy after staining with wheat germ agglutinin conjugate with Alexafluor488 (WGA488) to label exopolysaccharide matrix and Syto 85 to label bacterial cells. Persister status was induced using two different protocols: i) by exposing stationary phase Aim
Method
Optimal strategies for surgical and antimicrobial management of Patients treated at our institution with Aim
Method
Two stage revision is the most commonly used surgical treatment strategy for periprosthetic hip infections (PHI). The aim of our study was to assess the intra- and postoperative complications during and after two stage revision using resection arthroplasty between ex- and reimplantation. In this retrospective cohort study, all patients treated with a two stage revision using resection arthroplasty for PHI were included from 2008 to 2014. During the first stage, the prosthesis was removed resulting in a resection arthroplasty without the use a PMMA spacer. During second stage, (cemented or uncemented) reimplantation of the hip prosthesis was performed. The cohort was stratified into two groups according to the length of prosthesis-free interval (≤10 weeks and >10 weeks). Data on complications during explantation, prosthesis-free interval, reimplantation, and after reimplantation was collected. The overall complication rate between both groups was compared using the chi-squared test. The revision-free and infection-free survival was estimated using Kaplan-Meier survival analysis.Aim
Method
Ciprofloxacin was tested alone and in combination with Pyo-bacteriophage cocktail against Aim
Method
Spinal implant-associated infections (SIAI) require combined surgical and antimicrobial treatment and prolonged hospital stay. We evaluated the clinical, laboratory, microbiological and radiological characteristics and treatment approaches in patients with SIAI. Consecutive adult patients with SIAI treated between 2015 and 2017 were prosepctively included. SIAI was defined by: (i) significant microbial growth from intraoperative tissue or sonication fluid, (ii) intraoperative purulence, secondary wound dehiscence or implant on view, (iii) radiographic evidence of infection and fever (>38°C) without other recognized cause, increasing back pain or neurologic impairment, (iv) peri-implant tissue inflammation in histopathology.Aim
Method
To assess the analytical performance and to establish the cut-off of synovial fluid D-lactate concentration for the diagnosis of prosthetic joint infection (PJI) and septic arthritis (SA) using commercial kits provided by two manufacturers (A and B). We prospectively included patients with native or prosthetic joints undergoing synovial fluid aspiration as routine diagnostic procedure. Among 224 patients with prosthetic joints, 137 patients had aseptic loosening (AL) and 87 were diagnosed with PJI. Among 71 patients with native joints, 39 were diagnosed with osteoarthrosis (OA) and 32 with SA.Aim
Method
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. 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.Aim
Method
Radiologic signs such as radiolucent lines around the implant, hardware fracture or displacement and periosteal reaction have been considered suggestive of implant-associated infection. The goal of this study is to assess the correlation of these signs with confirmed internal fixation-associated infection evaluated in a prospective cohort. We evaluated the radiologic appearance of preoperative standard x-ray images in 421 surgeries performed in 380 patients with internal fixation device in place (56.8% male, mean age 53 ± 17 years). This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. Infection was suspected preoperatively in only 23.8% of the surgeries. The most common indications for surgeries in which infection was not suspected were nonunion (84 cases) and symptomatic hardware (57 cases). All removed implants were sent to sonication for biofilm removal and detection. In addition, several peri-implant tissue samples were collected. Radiographs were analyzed in a blinded fashion for signs of radiolucent lines around the implant before removal, hardware fracture or displacement, and soft periosteal reactions suggestive of infection. Diagnosis was established according to the IDSA criteria for PJI. Contingency tables were constructed to determine sensitivity and specificity, and to perform Chi-square tests to compare the presence of infection with radiological signs of infection.Aim
Method
Unexpected positive infections are distinct entity in prosthetic revision surgery. The prevalence and characteristics of unexpected positive cultures in internal fixation are however less established. The aim of this study was to describe the prevalence and characteristics of unexpected diagnosis of infection in a prospective cohort of revision surgeries following internal fixation. We reviewed the microbiological results following 356 surgeries that included partial or complete removal of internal fixation, performed in 328 patients (54% male, mean age 53 ± 17 years), in which infection was not initially suspected. This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. The implants most commonly removed were plate and/or screws (281 cases, 78,9%), followed by intramedullary nails (64 cases, 18,0%). The main indications for surgery were nonunion (89 cases, 25%) and symptomatic hardware (70 cases, 19,7%). All removed implants were sonicated, and tissue cultures were obtained depending on the surgeon's criteria. Diagnosis of infection was established by the presence of 2 or more positive tissue cultures (1 with a highly virulent microorganism), or ≥ 50 colony-forming units found in the sonication fluid.Aim
Method
The increase of antimicrobial resistance reduces treatment options for implant-associated infections caused by methicillin-resistant Rifampin, fosfomycin, vancomycin and daptomycin were tested alone and in combination with Aim
Methods
Phage therapy has attracted attention as a promising alternative treatment option for biofilm infections. To establish a successful phage therapy, a comprehensive stock of different phages covering a broad bacterial spectrum is crucial. We screened human and environmental sources for presence of lytic phages against selected bacteria. Saliva collected from 10 volunteers and 500 ml of sewage water were screened for the presence of lytic phages active against 20 clinical strains of Aim
Methods
The diagnosis of prosthetic-joint infection (PJI) is challenging, as bacteria adhere on implant and form biofilm. Therefore, current diagnostic methods, such as preoperative culture of joint aspirate have limited sensitivity with false-negative results. To evaluate the performance of measurement synovial fluid (SF) D-lactate (as a pathogen-specific marker) for the diagnosis of PJI and estimate of treatment success. 224 patients undergoing removal knee or hip prosthesis were included in the study between January 2015 and March 2017. 173 patients of this group had aseptic loosening of prosthesis and 87 were diagnosed with PJI. Prior to surgery, synovial fluid routine culture, D-lactate test, leukocyte count and neutrophils (%) were performed for each patient. In order to evaluate a treatment success, the measurement of SF D-lactate before second two-stage exchange procedure (after treatment) was implemented in 30 patients. Diagnosis of PJI was established according to modified Zimmerli criteria.Aim
Method
The aim of the study was to assess the accuracy of the alpha defensin lateral flow test for diagnosis of periprosthetic joint infection (PJI) using an optimized diagnostic algorithm and three classification systems. In addition, we compared the performance with synovial fluid leukocyte count, the most sensitive preoperative test. In this prospective multicenter study we included all consecutive patients with painful prosthetic hip and knee joints undergoing diagnostic joint aspiration. Alpha defensin lateral flow test was used according to manufacturer instructions. The following diagnostic criteria were used to confirm infection: Musculoskeletal Infection Society (MSIS), Infectious Diseases Society of America (IDSA) and Swiss orthopedics and Swiss Society of Infectious Diseases (SOSSID). In the latter, PJI was confirmed when at least one of following criteria applied: macroscopic purulence, sinus tract, positive cytology of joint aspirate (>2000 leukocytes/μl or >70% granulocytes), histological proof of acute inflammation in periprosthetic tissue, positive culture (from aspirate, tissue or sonication fluid). Infection was classified as chronic, if symptom duration was more than 3 weeks or if infection manifested after more than 1 month after surgery. The sensitivity and specificity of the alpha defensin lateral flow test and leukocyte count in synovial fluid were calculated and compared using McNemar Chi-square test.Aim
Method
The incidence of hematogenous periprosthetic joint infections (hPJI) is unknown and the cases probably largely underreported. Unrecognized and untreated primary infectious foci may cause continuous bacteremia, further spread of microorganisms and thus treatment failure or relapse of infection. This study aimed at improving knowledge about primary foci and microbiological characteristics of this entity to establish preventive measures and improve diagnostic and therapeutic strategies to counteract hPJI. We retrospectively analysed all consecutive patients with hPJI, who were treated at our institution from January 2010 until December 2016. Diagnosis of PJI was established if 1 of the following criteria applied:(i) macroscopic purulence, (ii) presence of sinus tract, (iii) positive cytology of joint aspirate (>2000 leukocytes/μl or >70% granulocytes), (iv) significant microbial growth in synovial fluid, periprosthetic tissue or sonication culture of retrieved prosthesis components, (v) positive histopathology. PJI was classified as hematogenous if the following criteria were fulfilled additionally: (1) onset of symptoms more than 1 month after arthroplasty AND (2) i) isolation of the same organism in blood cultures OR ii) evidence of a distant infectious focus consistent with the pathogen.Aim
Method
Alpha-defensin is a new synovial fluid biomarker for the diagnosis of periprosthetic joint infections (PJI). We compared the performance of two different alpha-defensin assays: quantitative ELISA test and qualitative lateral flow test. In this prospective cohort study, consecutive patients with a painful prosthesis of the lower limb were eligible for inclusion. In addition to standard diagnostics of PJI, alpha-defensin was determined in the aspirated synovial fluid between October 2016 and April 2017. PJI was defined according to the modified Zimmerli criteria, the Musculoskeletal Infection Society (MSIS) criteria and the Infectious Disease Society of America (IDSA) criteria. A positive quantitative alpha-defensin test was defined at a cut-off value of 5.2 mg/L. The sensitivity, specificity, accuracy and area under the curve of each test were determined and the AUCs were compared among each other.Aim
Method
Periprosthetic joint infections (PJI), caused by pathogens, for which no biofilm-active antibiotics are available, are often referred to as difficult-to-treat (DTT). It is unclear whether DTT PJI has worse outcome due to unavailability of biofilm-active antibiotics. We evaluated the outcome of DTT and non-DTT PJI managed according to a standardized treatment regimen. Patients with hip and knee PJI from 2013 to 2015 were prospectively included and followed-up for ≥2 years. DTT PJI was defined as growth of microorganism(s) resistant to biofilm-active antibiotics. The Kaplan-Meier survival analysis was used to compare the probability of infection-free survival between DTT and non-DTT PJI.Background
Methods
To assess the clinical characteristics, diagnostic tests and treatment strategies in orthopedic implant-associated infections (OIAI) caused by Cutibacterium spp. We retrospectively included consecutive patients with OIAI caused by Cutibacterium spp. treated at our institution from January 2012 to January 2017. OIAI was diagnosed when: (i) macroscopic purulence, sinus tract or exposed implant was present; (ii) acute inflammation in peri-implant-tissue was documented; (iii) Cutibacterium spp. grew in joint aspirate, ≥2 intraoperative peri-implant tissue samples or in sonication fluid of the removed implant (>50 CFU/ml).Aim
Method
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
The risk of haematogenic periprosthetic joint infection (PJI) after dental procedures is discussed controversially. To our knowledge, no study has evaluated infections according to the origin of infection based on the natural habitat of the bacteria. We investigated the frequency of positive monomicrobial cultures involving bacteria from oral cavity in patients with suspected PJI compared to bone and joint infections without joint prosthesis. In this retrospective study we included all patients with suspected PJI or bone and joint infection without endoprosthesis, hospitalized at our orthopaedic clinic from January 2009 through March 2014. Excluded were patients with superficial surgical site infections or missing data. Demographic, clinical and microbiological data were collected using a standardized case report form. Groups were compared regarding infections caused by oral bacteria. χ2 test or Fisher's exact test was employed for categorical variables and t-test for continuous variables.Aim
Method
The primary aim of this in vitro study was to test the efficacy of daptomycin to eradicate staphylococcal biofilms on various orthopedic implant surfaces and materials. The secondary aim was to quantitatively estimate the formation of staphylococcal biofilm on various implant materials with different surface properties. We tested six clinically important biomaterials: cobalt chrome alloy, pure titanium, grid-blasted titanium, porous plasma-coated titanium with/without hydroxyapatite, and polyethylene. Two laboratory strains of bacteria commonly causing PJI were used, namely The time to detection expressed as the heat flow >50 µW (TTD-50) indirectly quantifies the initial amount of biofilm bacteria, with a shorter TTD-50 representing a larger amount of bacteria.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
To evaluate antimicrobial activity of Sb-1 and Pyo-bacteriophage in preventing and eradicating MRSA biofilm Two Aim
Method
To investigate the antimicrobial activity of a gentamicin-loaded bone graft substitute (GLBGS) in the prevention and eradication of bacterial biofilms associated with prosthetic joint infections (PJI). The GLBGS (17,5 mg gentamicin/ml paste) with 40% hydroxyapatite/60% calcium sulfate1 was tested against biofilms of methicillin-resistant Aim
Method
Despite the lack of data regarding the diagnostic validity of synovial aspiration in Girdlestone hips a Girdlestone-aspiration is often performed before reimplantation to detect a possible persistence of infection during two staged revision total hip arthroplasty (THA). The aim of this study was to assess the diagnostic performance of the synovial aspiration in Girdlestone hips, without a PMMA-Spacer, for the detection of infection persistence prior to THA reimplantation. Seventy four patients undergoing a two staged revision THA surgery between 2006 and 2013 were included in this retrospective cohort study. Both synovial cultures and CRP values were acquired before explantation of the THA and of the Girdlestone hip before reimplantation. An antibiotic holiday of 14 days was observed prior to synovial aspiration. A PJI was defined according to the following criteria: intraarticular presence of pus or a sinus tract, a periprosthetic membrane indicative of infection in the histological analysis, or a positive microbiological isolation in a minimum of two samples.Introduction
Methods
The main reasons for hip prosthesis failure are aseptic loosening and periprosthetic joint infection (PJI). The real frequency of PJI is probably largely underestimated because of non-standardized definition criteria, diagnostic procedure, treatment algorithm and other confounders. Therefore, data from joint registries are not reflecting the frequency of PJI and can be misleading; particularly low-grade PJI can be frequently misdiagnosed as aseptic failure. Therefore, prospective clinical studies with standardized protocol, comprehensive diagnostic procedure and sufficient follow-up should be performed. Sonication of explanted prosthesis is highly sensitive for detection of biofilms on prosthetic surface and allows quantitative analysis of biofilm formation. We hypothesize that by using sonication, ceramic components (BIOLOX®delta, BIOLOX®forte) will show higher resistance against biofilm adhesion compared to polyethylene (PE) and metal (CoCrMo). In this prospective multicentre study (level of evidence: Ia), we included all consecutive adults ≥18 years of age, who underwent explantation of the hip prosthesis for infection or aseptic reason. Excluded were patients in whom part of the prosthetic components were retained. A standardized and comprehensive diagnostic algorithm was applied, including sonication of all removed prosthetic components for qualitative and quantitative microbiological analysis (ultrasound bath 40 kHz, 1 W/cm2, 1 min). Individual components (metal, PE, ceramic) were separately placed in sterile boxes for investigation. All patients were simultaneously included in the European Prosthetic joint infection cohort (EPJIC, Background
Methods
The aim of the present study was to assess the antibiofilm activity of daptomycin- and vancomycin-loaded poly(methyl methacrylate) (PMMA) and PMMA-Eudragit RL100 (EUD) microparticles against mature biofilms of polysaccharide intercellular adhesin-positive S. epidermidis. The effect of plain, daptomycin- and vancomycin-loaded PMMA and PMMA-EUD microparticles on S. epidermidis biofilms was assessed by isothermal microcalorimetry (IMC) and fluorescence in situ hybridization (FISH). Biofilms were grown for 48h onto poly-urethane pieces of fixed dimensions. Each sample was washed with PBS in order to remove planktonic bacteria and incubated for 24h with different concentrations of acrylic microparticles (20–1.25 mg/mL). The minimal biofilm inhibitory concentration (MBIC) of the antibiotic-loaded particles was defined as the lowest concentration of particles that was able to prevent heat flow associated to the recovery of the biofilms. After incubation with the microparticles, sessile cocci were hybridized with the pan-bacterial EUB338-FITC and the staphylococci-specific STAPHY-FICT probes and stained with DAPI. Biofilm structure and metabolic state were characterized by fluorescence microscopy. According to the IMC results, plain PMMA-particles showed no effect on S. epidermidis biofilms, whereas PMMA-EUD-microparticles negatively influenced the recovery of the biofilm probably due to the highly positive charge of these particles. The MBIC of daptomycin-loaded PMMA-microparticles was 20 mg/mL, whereas vancomycin-loaded PMMA microparticles were not able to inhibit biofilm recovery. Adding EUD to the formulation reduced the MBIC of daptomycin-loaded microparticles to 1.25 mg/mL, corresponding to a 16-fold reduction. Regarding the vancomycin-loaded microparticles, EUD caused a further decrease of their antibiofilm activity. The FISH micrographs corroborated the IMC results and provided additional insights on the antibiofilm effect of these carriers. According to FISH, daptomycin-loaded PMMA-EUD microparticles were responsible for the most pronounced reduction in biofilm mass. In addition, FISH showed that both PMMA and PMMA-EUD microparticles were able to attach to the biofilms. Adding EUD to the formulations proved to be a powerful strategy to improve daptomycin-loaded microparticles antibiofilm activity. In addition, the combination of IMC and FISH was essential in order to fully assess the effect of polymeric microparticles on sessile S. epidermidis. Although the present study enabled gaining further insights on this subject, the nature of these interactions remains unclear. However, this may be a crucial aspect for the enhancement of antibiofilm activity of antibiotic-loaded polymeric microcarriers against mature biofilms. This work was supported by the Portuguese government (Fundação para a Ciência e a Tecnologia) and FEDER (grant SFRH/BD/69260/2010 and research project EXCL/CTM-NAN/0166/2012) and strategic project PEst-OE/SAU/UI4013/2011.
We have prospectively studied the outcome of infections associated with implants which were retained and treated using a standardised antimicrobial protocol. Over a period of four years, we studied 24 consecutive patients who had symptoms of infection for less than one year, a stable implant, no sinus tract and a known pathogen which was susceptible to recommended antimicrobial agents. The infections involved hip prostheses (14), knee prostheses (5), an internal fixation device (4), and an ankle prosthesis (1). Twenty patients had a successful outcome at a median follow-up of 3.7 years (1.8 to 4.7); four had failure of the implant after a median follow-up of 1.2 years (0.3 to 2.5). The probability of survival without failure of treatment was 96% at one year (95% confidence interval (CI) 88 to 100), 92% at two years (95% CI 80 to 100) and 86% at three years (95% CI 72 to 100). Patients with a short-term infection but with a stable implant, no sinus tract and a known pathogen may be successfully treated by retention of the implant and the use of a standardised regimen of antimicrobial treatment.