Aim. Orthopedic implants play a tremendous role in fixing bone damages due to aging as well as fractures. However, these implants tend to get colonized by bacteria on the surface, leading to infections and subsequently prevention of healing and osteointegration. Recently, Roupie et al. showed that a nisin layer-by-layer based coating applied on biomaterials has both osteogenic and antibacterial properties. The Galleria mellonella larva is a well-known insect infection model that has been used to test the virulence of bacterial and fungal strains as well as for the high throughput screening of antimicrobial compounds against infections. Recently, we have developed an insect infection model with G. mellonella larvae to study implant-associated biofilm infections using Kirschner (K)-wires as implant material. Here, we would like to test the antibacterial capacity of nisin layer-by-layer based coatings on K-wires against Staphylococcus aureus in the G. mellonella larva implant infection model. Method. Prior to the implantation procedure, G. mellonella larvae are maintained at room temperature on wheat germ in an incubator. The larvae received bare titanium K-wires (uncoated), or either control-coated or nisin-coated K-wires. After one hour, the larvae were injected with 5×10. 5. S. aureus bacteria per larva (i.e., hematogenous implant infection model). Next, the larvae were incubated at 37. o. C in an incubator and the survival of the larvae was monitored for five days. Moreover, the number of bacteria on the implant surface and in the surrounding tissue was determined after 24h of incubation. Further, scanning electron microscopy (SEM) analyses were performed to study the effect of nisin on biofilm formation. Results. The larvae receiving the nisin-coated K-wires showed significantly higher survival rates compared to uncoated titanium K-wires, although not when compared to control-coated K-wires. A more than 1-log reduction in number of bacteria on the implant surface and in the surrounding tissue was observed in larvae receiving the nisin-coated K-wires, when compared to uncoated titanium K-wires SEM analysis showed reduced colonization of the bacteria nisin-coated K-wires compared to the controls. Conclusions. In conclusion, the antimicrobial nisin layer-by-layer based coating applied on titanium surfaces is able to prevent implant-related S. aureus biofilm infection in G. mellonella and is a promising antimicrobial strategy to prevent implant-related infections

Aim. Treatment of prosthetic joint infection (PJI) by systemic administration of high doses of long-term antibiotics often proves ineffective, causing severe side effects. Thus, we presented the phage Sb-1, which coding extracellular polymeric substances (EPS) degradation depolymerases, conjugated with rifampicin-loaded liposomes (Lip-RIF@Phage) by bio-orthogonal functionalization strategy to target biofilm (Figure1). Method. Methicillin-resistant Staphylococcus aureus (MRSA) biofilm was grown on porous glass beads for 24 h in vitro. After the biofilm formation, beads were exposed to 0.9% saline, then sonication. Quantitative and qualitative biofilm analyses were performed by colony counting, scanning electron microscopy and isothermal microcalorimetry. A rat model of total knee arthroplasty infected with the bioluminescent MRSA strain was developed as the PJI model to evaluate the efficacy of Lip-RIF@Phage anti-biofilm therapy in vivo, then the creatinine, alanine transaminase, and aspartate transaminase values were evaluated throughout the entire treatment process. Results. After treatment with Lip-RIF@Phage, no bacterial colonies were observed, consistent with findings from scanning electron microscopy. Similarly, isothermal microcalorimetry revealed no detectable heat following Lip-RIF@Phage treatment, aligning with these observations. In vivo experiments demonstrated a significant reduction in biofilm cell load compared to all other tested conditions, with no evidence of systemic toxicity on renal and liver functions attributed to Lip-RIF@Phage. Conclusions. The innovative depolymerase-phagobot nanosystem (Lip-RIF@Phage) exhibits remarkable efficacy in completely eliminating biofilm cells in vitro. It serves as an excellent carrier for antibiotic delivery, enhancing antibiotic penetration through biofilms and improving biofilm eradication efficacy. Furthermore, it enables personalized treatment strategies against biofilm-associated multidrug-resistant (MDR) infections by maximizing the effectiveness of any remaining sensitive antibiotics. For any tables or figures, please contact the authors directly

Aim. Antimicrobial peptides occur naturally in our intrinsic immune system. PLG0206 is a novel, engineered, 24-amino acid peptide which has broad-spectrum antimicrobial activity, including in biofilm and against multi-drug resistant pathogens (1,2). This is the first clinical study to evaluate the safety and tolerability of PLG0206 when administered via an irrigation solution in patients with periprosthetic joint infections (PJI) following total knee arthroplasty (TKA) during debridement, antibiotics, and implant retention (DAIR). Secondary objectives were to evaluate pharmacokinetics (PK), biomarkers and initial clinical efficacy at one year post-DAIR procedure. Method. This prospective, multicenter, open-label, interventional study assessed two dose levels of PLG0206. Fourteen patients underwent revision for PJI after TKA. At the end of debridement, they received a single intra-articular irrigation of PLG0206 into the wound cavity lasting 15 minutes at concentrations of 3 mg/mL (n=7) or 10 mg/mL (n=7). Patients received post-operative care and intravenous/oral antimicrobial therapy as per their institutional guidelines. Patients were monitored for safety and signs of relapse or persistent infection for 12 months post study drug administration and PK and blood biomarkers were assessed. Results. All patients completed their final study assessment at Day 365. Over the 1-year follow-up, only one recurrence (7%) was noted at Day 169 in the low-dose cohort. Following dosing, nine patients (64.3%) had limited systemic exposure; maximum plasma concentration occurred 1-hour post-administration and declined rapidly to undetectable levels by 24 hours following treatment in all patients. The incidence of drug related treatment-emergent adverse events (TEAEs) was low. Two patients, both in the higher dose cohort, experienced a transient drug related TEAE; one of hypertransaminasaemia and one of neuralgia. Both events were moderate in severity and resolved within two weeks of onset. Conclusions. A single 15-minute irrigation of PLG0206 into the wound cavity of patients undergoing a DAIR procedure for PJI following TKA, is safe and well tolerated by patients. This new antimicrobial peptide offers a promising therapeutic option in musculoskeletal infection. The initial clinical efficacy is encouraging but now needs to be investigated in a much larger clinical trial

Aim. Arthroscopic interventions have revolutionized the treatment of joint pathologies. The appropriate diagnostics and treatment are required for infections after ligament reconstructions using non-resorbable material such as tendon grafts, anchors, and sutures, prone to biofilm formation. The infection rate is around 1% for knee and shoulder, while up to 4% for Achilles tendon reconstructions. Despite high number of these procedures worldwide, there is limited evidence about the best treatment protocol. Our study aimed to provide a general protocol for the treatment of small implants for soft tissue reconstruction. Method. Between 2019 and 2023, we treated 48 infections of ligament, meniscus, and tendon reconstructions out of 7291 related procedures performed in the same time period. Early infection (<30 days) were treated with an arthroscopic debridement and implant retention (DAIR), except Achilles tendons had open DAIR, while those with delayed or chronic infection (>30 days) were treated with extensive debridement and lavage combined with one-stage exchange (OSE) or implant removal. During surgery, at least 5 microbiological s and samples for histopathology were obtained. The removed material was sonicated. After surgery, all patients were one week on iv. antibiotics, followed by oral antibiofilm antibiotics for 6 weeks including rifampicin and/or a quinolone. All patients were followed for at least 1 year. Failure was defined as the need for additional revision surgery after finished iv. antibiotic treatment. Results. Among 48 patients, 38 were early and 10 were late acute or chronic infections. The incidence of infection for our cohort was 0.7%. We observed 27 infections after ligament reconstruction of the knee, 15 of the shoulder, 5 of the ankle, and 1 infection of the elbow joint. 40 patients were treated with DAIR, 5 with OSE, and 3 with implant removal. We had 11 C. acnes, 10 S. aureus, 6 S. epidermidis, 2 P. aeruginosa, 2 S. lugdunensis, 10 mixed flora, and 3 culture-negative infections. 12 patients received antibiotics before surgery, and all culture-negative infections were related to this subgroup. We observed 2 failures, both in a combination of proximal tibial osteotomy and ligament reconstruction of the knee joint. The success rate of our protocol was 96%. Conclusions. Prompt surgical treatment followed by 6 weeks of antibiotic treatment cured 96% of infections of small implants after reconstruction procedures of knee, shoulder, and ankle joints. Our study is the first to provide a treatment protocol for infections of small implants after ligament reconstruction procedures

Aim. The management of PJIs is slowed down by the presence of bacteria forming biofilms where they may withstand antibiotic therapy. The use of adjuvant strategies, such as hydrolytic enzymes cocktail targeting biofilm matrices and facilitating their dispersion, is a promising option to limit impact of biofilms. Our aim was to evaluate the effect of enzymes cocktail combined with antibiotic dual therapy of rifampicin and vancomycin in a relevant in-vitro model. Method. Mature methicillin-resistant Staphylococcus aureus biofilms were grown on Ti-6Al-4V coupons by adding 1mL of a 8Log10 ATCC 33591 suspension in TGN (TSB + 1% glucose + 2% NaCl) to 24-wells plates containing the coupons and incubating the plates for 24h at 37°C with a continuous 50rpm agitation. The samples were rinsed and placed in 6 wells plates containing 1ml of the enzymatic cocktail (C.D.D.) solution (tris-buffered (pH 7.0) solution of 400 U/ml of aspecific DNA/RNA endonuclease, 50 U/ml of endo-1,4-b-D-glucanase, and 0.06 U/ml of β-N-acetylhexosaminidase). 9ml of TGN or TGN containing antibiotics RIF/VAN (rifampicin 5µg/mL + vancomycin 8µg/mL) at clinically relevant concentrations found locally in bone or joints, was then added and the samples were incubated in identical conditions for 24h. The samples were then recovered and rinsed. CFU counts were obtained by recovering the bacteria with sonication, serial dilutions, and TSA plating. Biomass was determined via crystal violet staining, followed by dye solubilization in acetic acid, and absorbance measurement using a spectrophotometer. Results. Significant reductions in bacterial counts were observed in biofilms exposed to either RIF/VAN or RIF/VAN+CDD, by respectively 2,6 and 3,7Log10 when compared to samples reincubated with TGN alone (p <0.05). Additionally, CFU counts in samples exposed to RIF/VAN+CDD were reduced by 1,1Log10 when compared to those exposed to RIF/VAN (p<0,05). Significant reduction in biomass (-29,8%, p<0.05) was observed for coupons exposed to RIF/VAN+CDD when compared to C.D.D alone (figure 1). Conclusions. The concurrent utilization of enzymes with rifampicin and vancomycin, holds promise as a feasible method to address periprosthetic joint infections (PJIs). For any tables or figures, please contact the authors directly

Aim. Diagnosis of prosthetic joint infection are often complicated by the presence of biofilm, which hampers bacteria dislodging from the implants, thus affecting sensitivity of cultures. In the last 20 years several studies have evidenced the usefulness of implant sonication to improve microbial recovery from biofilm formed on inert substrates. More recently, treatment of prosthetic joints and tissues with Dithiothreitol, a sulphur compound already used in routine diagnostic workflow for fluidification of respiratory samples, has proved to be not inferior to sonication in microbiological diagnosis of prosthetic joint infections. This study aimed to evaluate if the combination of the two treatments could further improve microbial retrieval from biofilm in an in vitro model. Method. Three isolates of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Eschericha coli and Pseudomonas aeruginosa responsible of prosthetic joint infections were used. They were grown onto 3 titanium discs (20 mm diameter) and incubated in 3 sterile plastic containers with 15 mL of Triptyc Soy Broth. After overnight incubation, not adhered cells were removed and fresh broth was added to each sample. After 48 hours incubation, the exausted broth was removed and one sample was used for sonication, one for treatment with 0,1% (v:v) Dithiothreitol and one treated with Dithiothreitol followed by sonication. Treated fluids were plated on Muller Hinton Agar plates for colony count. One-way ANOVA analysis was performed to evidence statistical differences between treatments. Results. Similar colony counts were observed for the 3 treatments: 10.1± 0.77 log CFU/mL for Dithiothreitol, 10.0 ± 0.75 for sonication and 10.1 ±0.73 for dithiothreitol + sonication. No statistical differences between the 3 treatments were evidenced by ANOVA analysis. Conclusions. Results seems to confirm that treatment with dithiothreitol is equivalent to sonication in recovering bacteria from biofilm grown on inert surface. Combining dithiotreitol treatment with sonication does not significantly improve bacterial recovery in respect to each treatment alone

Aim. Periprosthetic joint infections follow 1-3% of arthroplasty surgeries, with the biofilm nature of these infections presenting a significant treatment challenge. 1. Prevention strategies include antibiotic-loaded bone cement; however, increases in cementless procedures means there is an urgent need for alternative local antimicrobial delivery methods. 2. A novel, ultrathin, silica-based sol-gel technology is evaluated in this research as an anti-infective coating for orthopaedic prosthetic devices, providing local antibiotic release following surgery. Method. Reduction in clinically relevant microbial activity and biofilm reduction by antimicrobial sol-gel coatings, containing a selection of antibiotics, were assessed via disc diffusion and microdilution culture assays using the Calgary biofilm device. 3. Proliferation, morphology, collagen, and calcium production by primary bovine osteoblasts cultured upon antibiotic sol-gel surfaces were examined, and cytotoxicity evaluated using Alamar blue staining and lactate dehydrogenase assays. Concentrations of silica, calcium and phosphorus compounds within the cell layer cultured on sol-gel coatings and concentrations eluted into media, were quantified using ICP-OES. Furthermore, cellular phenotype was assessed using alkaline phosphatase activity with time in culture. Results. Low antibiotic concentrations within sol-gel had an inhibitory effect on clinically relevant biofilm growth, for example 0.8 mg ml. -1. tobramycin inhibited clinically isolated S. aureus (MRSA) growth with an 8-log reduction in viable colony forming units. There was no significant difference in metabolic activity between untreated and sol-gel exposed primary bovine osteoblasts in elution-based assays. Reduction (2-fold) in metabolic activity in direct contact assays after 48 hours exposure was likely to be due to increased osteoinduction, whereas no impact upon cell proliferation were observed (p=0.92 at 14 days culture). The morphology of primary osteoblasts was unaffected by culture on sol-gel coatings and collagen production was maintained. Calcium containing nodule production within bovine osteoblastic cells was increased 16-fold after 14 days culture upon sol-gel. Conclusions. The ultrathin sol-gel coating showed low cytotoxicity, strong biofilm reducing activity and antimicrobial activity, which was comparable to antibiotics alone, demonstrating that sol-gel delivery of antibiotics could provide local antimicrobial effects to inhibit PJI growth without the need for bone cement. Future work will develop and evaluate sol-gel performance in an ex vivo explant bone infection model which will reduce the need for animal experimentation

Aim. Diagnosing low-grade periprosthetic joint infections (PJI) can be very challenging due to low-virulent microorganisms capable of forming biofilm. Clinical signs can be subtle and may be similar to those of aseptic failure. To minimize morbidity and mortality and to preserve quality of life, accurate diagnosis is essential. The aim of this study was to assess the performance of various diagnostic tests in diagnosing low-grade PJI. Methods. Patients undergoing revision surgery after total hip and knee arthroplasty were included in this retrospective cohort study. A standardized diagnostic workup was performed using the components of the 2021 European Bone and Joint Infection Society (EBJIS) definition of PJI. For statistical analyses, the respective test was excluded from the infection definition to eliminate incorporation bias. Receiver-operating-characteristic curves were used to calculate the diagnostic performance of each test, and their area-under-the-curves (AUC) were compared using the z-test. Results. 422 patients undergoing revision surgery after total hip and knee arthroplasty were included in this study. 208 cases (49.3%) were diagnosed as septic. Of those, 60 infections (28.8%) were defined as low-grade PJI (symptoms >4 weeks and caused by low-virulent microorganisms (e. g. coagulase-negative staphylococci, Cutibacterium spp., enterococci and Actinomyces)). Performances of the different test methods are listed in Table 1. Synovial fluid (SF) - WBC (white blood cell count) >3000G/L (0.902), SF - %PMN (percentage of polymorphonuclear neutrophils) > 65% (0.959), histology (0.948), and frozen section (0.925) showed the best AUCs. Conclusion. The confirmatory criteria according to the EBJIS definition showed almost ideal performances in ruling-in PJI (>99% specificity). Histology and synovial fluid cell count (SF-WBC and SF-%PMN) showed excellent accuracies for diagnosing low-grade PJI. However, a reduced immune reaction in these cases may necessitate lower cut-off values. Intraoperative frozen section may be valuable in cases with inconclusive preoperative diagnosis. For any tables or figures, please contact the authors directly

Introduction. In specific conditions, infection may lead to bone loss and is difficult to treat. 1. Current clinical approaches rely on the introduction of antibiotics. While these may be effective, there are concerns regarding the rise of antimicrobial resistance. There is therefore interest in the development of antimicrobial bone graft substitutes for dental and trauma surgery. Aim & Objectives. The incorporation of zinc into biomaterials has been shown to confer broad spectrum antimicrobial activity, but this has not yet been applied to the development of a commercial bone graft substitute. The aim of this research was therefore to prepare and characterise a series of zinc-substituted nanoscale hydroxyapatite (nHA) materials, including evaluation of antimicrobial activity. Method. Zinc (Zn) substituted nHA materials were prepared (0, 5, 10, 15 & 20 mol.% Zn) using a wet chemical precipitation method with a rapid mixing. (2). The reaction was carried out using zinc hydroxide at pH 10. The suspension formed was washed and dried into both powder & paste forms. The resultant powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The antimicrobial activity was evaluated against Staphylococcus aureus (S8650 strain - isolated from an osteomyelitis case), by two techniques. The Miles and Misra method was applied to determine the number of colony-forming units (CFUs) in bacterial suspensions incubated with pastes. Secondly, a biofilm initialization method was used to evaluate the capacity of the materials to prevent biofilm formation. One-way analysis of variance (ANOVA) was used for the statistical analysis and results with p-value < 0.05 were considered statistically significant. Results. XRD indicated the formation of pure hydroxyapatite with up to 10 mol.% Zn without any side products. However, when Zn was increased to 15 & 20 mol %, zinc oxide (ZnO) peaks were detected. The TEM showed nanoscale needle-like particles when Zn was increased compared to nHA particles. Regarding the antibacterial activity, ZnHA pastes at all concentrations caused a significant reduction in bacterial CFUs in a dose-dependent manner (50, 100 & 200 mg). Additionally, even the lowest zinc substitution (5 mol.%) significantly reduced biofilm formation. Conclusion. The results demonstrated a novel method to produce a Zn-substituted nHA that showed antimicrobial activity against a pathogen isolated from a bone infection

Aim. Prosthetic joint infections (PJI) remain a great challenge in orthopedic surgery with a high mortality rate. It is particularly complicated by biofilms and infections caused by Methicillin-resistant Staphylococcus aureus (MRSA). It concurrently shields bacteria from host immune responses and confers resistance to antibiotics. This study aims to investigate the efficacy of radioimmunotherapy as an innovative therapeutic modality to address the challenges posed by MRSA and its biofilm. Method. We induced specific monoclonal antibodies 4497-IgG1 as carriers, which target wall teichoic acids (WTA) existing on MRSA and its biofilm. Radionuclides actiniumr-225 (. 225. Ac, α-emitter) and lutetium-177 (. 177. Lu, β-emitter) were conjugated with mAbs using DOTA as chelator. Quality control was assessed using thin layer chromatography and immunoreactivity assays. . 225. Ac- and . 177. Lu-labelled 4497-IgG1 were employed to evaluate the susceptibility of MRSA and its biofilm to the radioimmunotherapy in vitro. Planktonic MRSA and biofilms, at concentrations of 10. 8. and 10. 7. CFU/mL, were incubated at 37°C for 60 minutes in PBS containing either . 225. Ac-mAb (0 - 14.8 kBq) or . 177. Lu-mAb (0 - 14.8 MBq). Radiolabelled dunituximab and free radionuclides serve as isotype-matched negative control. The bacterial viability and metabolic activity were subsequently quantified using CFU and XTT assays. Results. The radiochemical purity of the . 225. Ac-mAbs and . 177. Lu-mAbs complex were determined to be 95.4% and 96.16%. Immunoreactivity fractions of them were measured at 81.8% and 80.8%. . 225. Ac-mAbs and . 177. Lu-mAbs exhibited significant and dose-dependent antimicrobial effects on both planktonic MRSA and biofilm. . 225. Ac- and . 177. Lu-4497IgG1 at doses of 7.4 kBq and 7.4 MBq resulted in more than 4-log reduction in bacterial counts. In biofilms, 2-log reduction at the highest . 225. Ac radioactivity of 14,8kBq. The . 177. Lu complex showed a strong dose-dependent effect, with a reduction of up to 4-log. The XTT assay confirmed these findings, showing a decrease in metabolic activity corresponding to a decrease in bacterial counts, and a slight increase in metabolic activity at the lower dose. Conclusions. Our study demonstrates the efficacy of . 225. Ac and . 177. Lu-labelled 4497-IgG1 antibodies in mediating dose-dependent bactericidal effects against planktonic MRSA and biofilms in vitro. This indicates that radioimmunotherapy could be a potential targeted therapeutic strategy against MRSA and its biofilm. Further research in preclinical and clinical settings is warranted to validate and refine these findings on biofilm-associated implant infections

Aim. Irrigation and debridement with an irrigation solution are essential components of the surgical management of acute and chronic periprosthetic joint infection (PJI). Nevertheless, there is a lack of agreement regarding the most effective solution to use. The aim of the study was to perform a systematic review and meta-analysis of the current literature concerning the efficacy of different irrigation solutions over bacterial biofilm. Method. This study was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis extension for Network meta-analysis (PRISMA-NMA) checklist for systematic reviews and meta-analyses. A comprehensive literature search of PubMed, Cochrane Library, Web of Science and Scopus databases from inception to September 1, 2023. We combined terms related to PJI, biofilm and irrigation solutions studied in vitro. We performed a network meta-analysis to analyze which irrigation solution achieved a higher reduction of colony forming units (CFU) after specific exposure times, always with a maximum of five minutes, replicating intraoperative conditions. Effect-size was summarized with logarithmic response ratio (logRR) and 95% confidence intervals (95% CI). The rank probability for each treatment was calculated using the p-scores. Results. We screened 233 potential sources. Following deduplication, screening and full-text review, four studies with ten irrigation solutions for different duration of exposures were included, always less than five minutes, replicating intraoperative conditions. Solutions were studied over mature biofilms of most frequent bacteria grown over metal, bone cement or polyethylene surfaces. The highest effect was achieved with povidone iodine 10% during 5 minutes (logRR: −12.02; 95% CI: −14.04, −9.99). The best ranked solutions were povidone iodine 10% during five, three and one minute (respective p-scores: 0.977, 0.932, 0.887) and its combination with hydrogen peroxide for 3 minutes (p-score: 0.836). Povidone iodine 0.3% acting for 5 minutes completed the top 5 best ranked solutions in this study (p-score: 0.761). We assumed that there were no inconsistencies in our network because after examining both scenarios, with and without inconsistencies, the results were not significantly different. Conclusions. Our results show that 10% povidone-iodine is the best antiseptic solution when studied in vitro in the context of prosthetic joint infection. However, the included studies did not evaluate the possible cytotoxic effects of these solutions. This should also be taken into account before choosing the most appropriate antiseptic solution

Aim. In trauma surgery, the development of biomaterial-associated infections (BAI) is one of the most common complications affecting trauma patients, requiring prolonged hospitalization and the intensive use of antibiotics. Following the attachment of bacteria on the surface of the biomaterial, the biofilm-forming bacteria could initiate a chronic implant-related infection. Despite the use of conventional local and systemic antibiotic therapies, persistent biofilms involve various resistance mechanisms that contribute to therapeutic failures. The development of in vivo chronic BAI models to optimize antibiofilm treatments is a major challenge. Indeed, the biofilm pathogenicity and the host response need to be finely regulated, and compatible with the animal lifestyle. Previously, a Galleria mellonella larvae model for the formation of an early-stage biofilm on the surface of a Kirschner (K)-wire was established. In the present study, two models of mature biofilm using clinical Staphylococcus aureus strains were assessed: one related to contaminated K-wires (in vitro biofilm maturation) and the second to hematogenous infections (in vivo biofilm maturation). Rifampicin was used as a standard drug for antibiofilm treatment. Method. In the first model, biofilms were formed following an incubation period (up to 7 days) in the CDC Biofilm Reactor (CBR, BioSurface Technologies). Then, after implantation of the pre-incubated K-wire in the larvae, rifampicin (80 mg/kg) was injected and the survival of the larvae was monitored. In the second model, biofilm formation was achieved after an incubation period (up to 7 days) inside the larvae and then, after removing the K-wires from the host, in vitro rifampicin susceptibility assays were performed (according to EUCAST). Results. The first model indicate that in vitro biofilm maturation affects the bacterial pathogenicity in the host, depending on the S. aureus strain used. Furthermore, the more the biofilm is matured, the more the rifampicin treatment efficiency is compromised. The second model shows that, despite the fast in vivo biofilm formation in the host, the number of bacteria, either attached to the surface of the K-wire surface or in surrounding tissue of the larvae, was not increased over time. Conclusions. Altogether, these results allow the establishment of biofilm models using G. mellonella larvae in order to understand the impact of biofilm maturation on both the bacterial pathogenicity and the efficiency of antibiofilm treatments

Aim. Chemical debridement is a fundamental step during Periprosthetic joint infection (PJI) surgery. Antiseptic solutions are commonly used, but evidence on the optimal antiseptic, concentration, and irrigation time is lacking. The aim of this study is to analyze and compare the anti-biofilm capacity of povidone iodine, H. 2. 0. 2. , acetic acid and Bactisure™ after different exposure times, as well as their combinations. Method. Surgical steel discs inoculated with methicillin susceptible (MSSA) and resistant S. aureus (MRSA), P. aeruginosa, and S. epidermidis were exposed to the following antiseptic solutions: 0.3% (PI0.3) and 10% povidone iodine (PI10), H. 2. 0. 2. , 3% Acetic acid (AA3) and Bactisure™. Combinations included AA3, H. 2. 0. 2. , and PI10 in various orders. Exposure time for the antiseptics solutions was 1, 3 and 5 minutes, while combinations had a 9-minute total exposure, 3 minutes per antiseptic sequentially. All experiments were performed in triplicate and with a sterile saline control. nThe reduction in colony-forming units (CFU) was measured after sonication, and biofilm structure was analyzed via scanning electron microscopy. Results. PI showed the highest antibiofilm activity. PI0.3 eradicated bacteria on the discs after 3 and 5 minutes of exposure, but only achieved a 77.1% reduction after 1 minute. After PI10 treatment, we did not recover any bacteria regardless of exposure time. H. 2. 0. 2. , AA3, and Bactisure™ reached a significantly lower bacterial decrease at all exposure times compared to PI0.3 and PI10. AA3 was less effective against MSSA and S. epidermidis. H. 2. 0. 2. showed less activity against MRSA than PI0.3, PI10, and Bactisure™. Combinations of antiseptics starting with AA3 showed the best results in terms of CFU reduction and cell viability. Conclusions. We propose a sequential combination of AA3 + H. 2. 0. 2. + PI10 with an exposure time of 9 minutes for the chemical debridement in PJI surgery. First, AA3 performs debridement and disruption of the biofilm. Then, H. 2. 0. 2. has a bactericidal effect and increases the porosity of the cell wall, and PI10 has a final bactericidal effect. If combinations are unavailable, PI is a cost-effective alternative

Aim. Dalbavancin is a lipoglycopeptide with a broad antimicrobial spectrum against Gram-positive bacteria and effect against microorganisms in biofilm in vitro. Its pharmacokinetic properties, with an exceptionally long half-life of approximately 300 hours, allow for simplified administration that may be of value in the long-term treatment of bone and joint infections, such as prosthetic joint infections (PJIs). Several case reports and case series with “off-lable” treatment with dalbavancin of PJIs exist, but the optimal dosing regimen remains to be defined. Therapeutic drug monitoring (TDM) is recommended for treatment with >2 doses of dalbavancin. In the absence of TDM, the Swedish national guidelines for bone and joint infections (2023, . www.infektion.net. ) recommends a loading dose of dalbavancin 1,500 mg on day 1 and 1,500 mg on days 8 – 14, after which from day 28 1,000 mg is given biweekly or 500 mg every week. The aim of the present study was to determine trough levels of dalbavancin in patients with long-term treatment of PJIs according to the national guidelines. Method. Twelve patients with PJI were treated with at least 6 doses of dalbavancin, of which the first two doses were 1500 mg and the following doses were 1000 every second week, and prospectively sampled biweekly for determination of serum concentrations (trough levels) of dalbavancin which was measured by liquid chromatography coupled to electrospray tandem mass spectrometry (LC-MS/MS). The renal function was also examined. Results. The median serum concentration 14 days after the first dose of dalbavancin 1500 mg was 36.3 mg/L (range 6.6 – 62.4 mg/L). The median value 14 days after the second dose of 1500 mg (day 27 – 28) was 48.2 mg/L (range 12.2 – 77.3 mg/L). The trough value after the last dose of a total of 6 – 7 doses was as median 43.1 mg/L (range 26.2 – 97.5 mg/L). Three patients showed a tendency towards successive accumulation of dalbavancin during treatment. None of the patients, including those three with increasing through levels during treatment, showed any significant alteration in creatinine nor glomerular filtration rate. Conclusions. TDM during long-term treatment with dalbavancin is recommended to avoid the risk of accumulation and unnecessarily high trough values. With TDM, the dosing interval can be extended in several cases. In addition, with the support of TDM, subtherapeutic serum concentrations, with the risk of developing resistance, can be avoided

Periprosthetic joint infection represents a devastating complication after total elbow arthroplasty. Several measures can be implemented before, during, and after surgery to decrease infection rates, which exceed 5%. Debridement with antibiotics and implant retention has been reported to be successful in less than one-third of acute infections, but still plays a role. For elbows with well-fixed implants, staged retention seems to be equally successful as the more commonly performed two-stage reimplantation, both with a success rate of 70% to 80%. Permanent resection or even amputation are occasionally considered. Not uncommonly, a second-stage reimplantation requires complex reconstruction of the skeleton with allografts, and the extensor mechanism may also be deficient. Further developments are needed to improve our management of infection after elbow arthroplasty.

Cite this article: Bone Joint J 2024;106-B(11):1321–1326.

Aims. The efficacy of saline irrigation for treatment of implant-associated infections is limited in the presence of porous metallic implants. This study evaluated the therapeutic efficacy of antibiotic doped bioceramic (vancomycin/tobramycin-doped polyvinyl alcohol composite (PVA-VAN/TOB-P)) after saline wash in a mouse infection model implanted with titanium cylinders. Methods. Air pouches created in female BalBc mice by subcutaneous injection of air. In the first of two independent studies, pouches were implanted with titanium cylinders (400, 700, and 100 µm pore sizes) and inoculated with Staphylococcus aureus (1 × 10. 3. or 1 × 10. 6. colony-forming units (CFU)/pouch) to establish infection and biofilm formation. Mice were killed after one week for microbiological analysis. In the second study, pouches were implanted with 400 µm titanium cylinders and inoculated with S. aureus (1 × 10. 3. or 1 × 10. 6. CFU/pouch). Four groups were tested: 1) no bacteria; 2) bacteria without saline wash; 3) saline wash only; and 4) saline wash plus PVA-VAN/TOB-P. After seven days, the pouches were opened and washed with saline alone, or had an additional injection of PVA-VAN/TOB-P. Mice were killed 14 days after pouch wash. Results. The first part of the study showed that low-grade infection was more significant in 400 µm cylinders than cylinders with larger pore sizes (p < 0.05). The second part of the study showed that saline wash alone was ineffective in eradicating both low- and high-grade infections. Saline plus PVA-VAN/TOB-P eradicated the titanium cylinder-associated infections, as manifested by negative cultures of the washouts and supported by scanning electron microscopy and histology. Conclusion. Porous titanium cylinders were vulnerable to bacterial infection and biofilm formation that could not be treated by saline irrigation alone. Application of PVA-VAN/TOB-P directly into the surgical site alone or after saline wash represents a feasible approach for prevention and/or treatment of porous implant-related infections. Cite this article: Bone Joint Res 2024;13(11):622–631

Aims

The optimum type of antibiotics and their administration route for treating Gram-negative (GN) periprosthetic joint infection (PJI) remain controversial. This study aimed to determine the GN bacterial species and antibacterial resistance rates related to clinical GN-PJI, and to determine the efficacy and safety of intra-articular (IA) antibiotic injection after one-stage revision in a GN pathogen-induced PJI rat model of total knee arthroplasty.

Aims. We aimed to determine the concentrations of synovial vancomycin and meropenem in patients treated by single-stage revision combined with intra-articular infusion following periprosthetic joint infection (PJI), thereby validating this drug delivery approach. Methods. We included 14 patients with PJI as noted in their medical records between November 2021 and August 2022, comprising eight hip and seven knee joint infections, with one patient experiencing bilateral knee infections. The patients underwent single-stage revision surgery, followed by intra-articular infusion of vancomycin and meropenem (50,000 µg/ml). Synovial fluid samples were collected to assess antibiotic concentrations using high-performance liquid chromatography. Results. The peak concentrations of vancomycin and meropenem in the joint cavity were observed at one hour post-injection, with mean values of 14,933.9 µg/ml (SD 10,176.3) and 5,819.1 µg/ml (SD 6,029.8), respectively. The trough concentrations at 24 hours were 5,495.0 µg/ml (SD 2,360.5) for vancomycin and 186.4 µg/ml (SD 254.3) for meropenem. The half-life of vancomycin was 6 hours, while that of meropenem ranged between 2 and 3.5 hours. No significant adverse events related to the antibiotic administration were observed. Conclusion. This method can achieve sustained high antibiotic concentrations within the joint space, exceeding the reported minimum biofilm eradication concentration. Our study highlights the remarkable effectiveness of intra-articular antibiotic infusion in delivering high intra-articular concentrations of antibiotics. The method provided sustained high antibiotic concentrations within the joint cavity, and no severe side-effects were observed. These findings offer evidence to improve clinical treatment strategies. However, further validation is required through studies with larger sample sizes and higher levels of evidence. Cite this article: Bone Joint Res 2024;13(10):535–545

Aims

This study aimed to assess the risk of acute kidney injury (AKI) associated with combined intravenous (IV) and topical antibiotic therapy in patients undergoing treatment for periprosthetic joint infections (PJIs) following total knee arthroplasty (TKA), utilizing the Kidney Disease: Improving Global Outcomes (KDIGO) criteria for classification.

Aims. This study investigated vancomycin-microbubbles (Vm-MBs) and meropenem (Mp)-MBs with ultrasound-targeted microbubble destruction (UTMD) to disrupt biofilms and improve bactericidal efficiency, providing a new and promising strategy for the treatment of device-related infections (DRIs). Methods. A film hydration method was used to prepare Vm-MBs and Mp-MBs and examine their characterization. Biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were treated with different groups. Biofilm biomass differences were determined by staining. Thickness and bacterial viability were observed with confocal laser scanning microscope (CLSM). Colony counts were determined by plate-counting. Scanning electron microscopy (SEM) observed bacterial morphology. Results. The Vm-MBs and Mp-MBs met the experimental requirements. The biofilm biomass in the Vm, Vm-MBs, UTMD, and Vm-MBs + UTMD groups was significantly lower than in the control group. MRSA and E. coli biofilms were most notably damaged in the Vm-MBs + UTMD group and Mp-MBs + UTMD group, respectively, with mean 21.55% (SD 0.08) and 19.73% (SD 1.25) remaining in the biofilm biomass. Vm-MBs + UTMD significantly reduced biofilm thickness and bacterial viability (p = 0.005 and p < 0.0001, respectively). Mp-MBs + UTMD could significantly decrease biofilm thickness and bacterial viability (allp < 0.001). Plate-counting method showed that the numbers of MRSA and E. coli bacterial colonies were significantly lower in the Vm-MBs + UTMD group and the Mp, Mp-MBs, UTMD, Mp-MBs + UTMD groups compared to the control group (p = 0.031). SEM showed that the morphology and structure of MRSA and E. coli were significantly damaged in the Vm-MBs + UTMD and Mp-MBs + UTMD groups. Conclusion. Vm-MBs or Mp-MBs combined with UTMD can effectively disrupt biofilms and protectively release antibiotics under ultrasound mediation, significantly reducing bacterial viability and improving the bactericidal effect of antibiotics. Cite this article: Bone Joint Res 2024;13(9):441–451