Introduction. Multiple studies have identified Cutibacterium acnes (C.acnes) and other microbes in intervertebral disc tissue using 16S DNA Sequencing and microbial cultures. However, it remains unclear whether these bacteria are native to the discs or result from perioperative contamination. Our study aimed to detect Gram-positive bacteria in non-herniated human disc samples and explore correlations with Toll-like receptors (TLR) 2, TLR4, NLRP3, and Gasdermin D. Methods. Immunohistochemical staining was conducted on 75 human IVD samples for Gram-positive bacteria, S. aureus, C.acnes, TLR2, TLR4, NLRP3, and Gasdermin D. Cell detection and classification were performed using QuPath. NP cells were treated with Lipopolysaccharide (LPS) and Peptidoglycan (PGN) in monolayer and alginate beads for up to 72 hours, followed by secretome analysis using Luminex. Statistical analysis included Kruskal-Wallis, Dunn's multiple comparison test, and Pearson correlation. Results. Immunohistochemical staining revealed Gram-positive bacteria exclusively within cells, with C. acnes positivity ranging from 5–99% and correlating with patient age (r=0.41, p= 0.007). TLR2 positivity ranged from 5–99% and TLR4 from 3–72%, showing a strong correlation (r= 0.62, p= 1.5e-006). Females with mid-degenerative grades exhibited significantly decreased TLR2 expression compared to those without degeneration signs. Treatment with LPS and PGN increased catabolic cyto- and chemokines associated with IVD degeneration. Conclusion. In conclusion, this study confirms Gram-positive bacteria presence in non-herniated human disc samples and highlights their role in triggering a catabolic response in disc cells. No conflicts of interest.  . Sources of funding. This project is part of the Disc4All Training network to advance integrated computational simulations in translational medicine, applies to intervertebral disc degeneration and funded by Horizon 2020 (H2020-MSCA-ITN-ETN-2020 GA: 955735)

Objectives. This study aims to investigate whether bacteria are present in intervertebral discs (IVDs) and their influence. Causality between chronic infection of the IVD and its degenerative process gained great interest recently. Granville Smith et al. (2021) identified 36 articles from 34 research studies investigating bacteria in IVDs, from these 27 studies found, Cutibacterium acnes being the most abundant. However, whether bacteria identified were present in vivo or if they represent contamination remains unclear. Methods. Human IVD tissue was fixed in paraffin and Immunohistochemical stained for Gram-positive bacteria. NP cells in monolayer have been stimulated with LPS (0.1–50 µg/ml) and Peptidoglycan (0.1–50 µg/ml) for 24, 48 and 72 hrs to investigate their influence. The concentration of proinflammatory and catabolic cytokines in the media is being measured using ELISA. RNA extracted and RT-qPCR utilised for factors associated with disc degeneration matrix genes, matrix degrading enzymes, cytokines, neurotrophic factors and angiogenic factors. Results. Bacteria were detected within IVD tissue. Bacteria was internalized by the NP cells and influenced the nuclei morphology. Preliminary results of the exposure of NP cells to bacterial components demonstrate that ADAMTS4 as well as IL-8 were showed an increase in gene expression after LPS and peptidoglycan treatment compared to the non-treated control. Underlining these results, IL-8 protein was increased in treated groups, whereas peptidoglycan treated groups showed a dose dependence. Conclusion. This study demonstrates that Gram positive bacteria are present within the IVD. The exposure of NP cells to peptidoglycans indicates that bacterial components trigger a stress response. Conflicts of Interest: No conflict of interest. Sources of Funding: This project is part of the Disc4All Training network to advance integrated computational simulations in translational medicine, applies to intervertebral disc degeneration and funded by Horizon 2020 (H2020-MSCA-ITN-ETN-2020 GA: 955735)

A key cause of low back pain is the degeneration of the intervertebral disc (IVD). Causality between infection of the IVD and its degenerative process gained great interest over the last decade. Granville Smith et al. (2021) identified 36 articles from 34 research studies investigating bacteria in human IVDs. Bacteria was identified in 27 studies, whereas 9 attributed bacterial presence to contamination. Cutibacterium acnes was the most abundant, followed by coagulase-negative staphylococcus. However, whether bacteria identified were present in vivo or represent perioperative contamination remains unclear. This study investigated whether bacteria are present in IVDs and what potential effects they may have on native disc cells. Immunohistochemical staining for Gram positive bacteria was performed on human IVD tissue to identify presence and characterise bacterial species. Nucleus pulposus (NP) cells in monolayer and 3D alginate were stimulated with LPS and Peptidoglycan (0.1-50 µg/ml) for 48hrs. Following stimulation qPCR for factors associated with disc degeneration including matrix genes, matrix degrading enzymes, cytokines, neurotrophic factors and angiogenic factors and conditioned media collected for ELISA and luminex analysis. Gram positive bacteria was detected within human IVD tissue. Internalisation of bacteria by NP cells influenced the cell and nuclei morphology. Preliminary results of exposure of NP cells to bacterial components indicate that LPS as well as Peptidoglycan increase IL-8 and ADAMTS-4 gene expression following 48 hours of stimulation with a dose response seen for IL-8 induction by peptidoglycan compared to the control group. Underlining these results, IL-8 protein release was increased for treated groups compared to non-treated control. Further analysis is underway investigating other output measures and additional biological repeats. This study has demonstrated bacteria are present within IVD cells within IVD tissue removed from degenerate IVD and is determining the potential influence of these on disc degeneration

The Global Burden of Disease Study 2019 showed a 33.4% increase in fractures and a 65.3% increase in Years lived with disability (YLD) since 1990. Although the overall rate of fracture related infection (FRI) is low, it increases to 30% in complex fractures. In addition, the implantation of foreign materials, such as fracture stabilizing implants, decreases the number of bacteria needed to cause an infection. Then, when infections do occur, they are difficult to treat and often require multiple surgeries to heal. The bacteria can persist in the canaliculi of the bony tissue, in cells, in a biofilm on material or necrotic bone or in abscess communities. In the last decades, different approaches have been pursued to modify biomaterials as well as implant surface and to develop antimicrobial surfaces or local drug release strategies. This talk will give an introduction to the problem of bony and implant associated infections and presents the development and preclinical (as well as clinical) studies of two approaches for local drug delivery

Aim. Antimicrobial resistance (AMR) aggravates an already difficult treatment of periprosthetic joint infections (PJI). The prevalence of drug-resistant pathogens varies across countries and increases over time. Regular monitoring of bacteriological analyses should be performed. Due to many factors influencing the AMR, the correct choice of antimicrobial management remains arguable. The primary purpose of this retrospective study was to identify and compare causative bacteria and to compare the incidence of antibiotic resistance between the septic revision total knee arthroplasty (TKA) and septic revision total hip arthroplasty (THA). Method. A review of all revision TKAs and revision THAs, undertaken between 2007 and 2020 in a tertiary referral centre, was performed. Included were cases meeting the consensus criteria for PJI, in which an organism has been identified. There were no major differences in tissue sampling between revision TKAs and revision THAs over time. Results. A total of 228 bacterial strains, isolated after revision TKA and THA, were analysed for their resistance to 20 different antibiotics. There was a statistically significant higher occurrence of Gram-negative bacteria (p=0.002) and Enterococcus species (p=0.026) identified after revision THAs compared to TKA. The comparison of antibiotic resistance between revision TKAs and revision THAs was statistically significant in 9 of 20 analysed antibiotics. Pathogens isolated after revision THA were much more resistant compared to pathogens isolated after revision TKA. Resistance in revision THAs was significantly higher to oxacillin (p=0.03), ciprofloxacin (p<0.001), levofloxacin (p<0.001), moxifloxacin (p=0.005), clindamycin (p<0.001), co-trimoxazole (p<0.001), imipenem (p=0.01), rifampicin (p=0.005) and tetracycline (p=0.009). There was no significantly higher resistance of pathogens isolated after revision TKAs detected. No statistically significant difference in antibiotic resistance of Gram-negative bacteria between revision TKA and revision THA was observed. Conclusions. The occurrence and the resistance of bacteria to antibiotics differs significantly between revision TKAs and revision THAs. This has implications on of the choice of empirical antibiotic in revision surgery as well as prophylactic antibiotic in primary surgery, depending on the joint that is to be replaced

Prosthetic joint infections represent complications connected to the implantation of biomedical devices, they have high incidence, interfere with osseointegration, and lead to a high societal burden. The microbial biofilm, which is a complex structure of microbial cells firmly attached to a surface, is one of the main issues causing infections. Biofilm- forming bacteria are acquiring more and more resistances to common clinical treatments due to the abuse of antibiotics administration. Therefore, there is increasing need to develop alternative methods exerting antibacterial activities against multidrug-resistant biofilm-forming bacteria. In this context, metal-based coatings with antimicrobial activities have been investigated and are currently used in the clinical practice. However, traditional coatings exhibit some drawbacks related to the insufficient adhesion to the substrate, scarce uniformity and scarce control over the toxic metal release reducing their efficacy. Here, we propose the use of antimicrobial silver-based nanostructured thin films to discourage bacterial infections. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture, allow tuning silver release, and avoid delamination. To mitigate interference with osseointegration, here silver composites with bone apatite and hydroxyapatite were explored. The antibacterial efficacy of silver films was tested in vitro against gram- positive and gram-negative species to determine the optimal coatings characteristics by assessing reduction of bacterial viability, adhesion to substrate, and biofilm formation. Efficacy was tested in an in vivo rabbit model, using a multidrug-resistant strain of Staphylococcus aureus showing significant reduction of the bacterial load on the silver prosthesis both when coated with the metal only (>99% reduction) and when in combination with bone apatite (>86% reduction). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses

Aims. Prosthetic joint infection (PJI) remains the most severe complication of arthroplasty. Failure of intensive, long-term antibiotic treatment for PJI often requires removal of the implant. Antibiotic failure is thought to be caused by biofilm and persister formation. Novel anti-biofilm and anti-persister strategies are urgently needed. Here, we investigated the effects of several antimicrobial peptides on the bacteria within antibiotic-treated biofilms in an in vitro mature biofilm model on abiotic surfaces. Methods. On polystyrene, a mature (7 day-old) methicillin-resistant Staphylococcus aureus (MRSA) biofilm was developed. Thereafter, bacteria in the biofilm were exposed to rifampicin and ciprofloxacin (both 10× >MIC) for three days. Surviving bacteria in the antibiotic-treated biofilm, presumed to include persisters, were exposed to increasing doses of the antimicrobial peptides SAAP-148, acyldepsipeptide 4 (ADEP4), LL-37 and pexiganan. SAAP-148 was further tested on antibiotic-treated mature biofilms on titanium/aluminium/niobium (TAN) discs and prosthetic joint liners. Results. Daily exposure of the mature biofilm for seven days with antibiotics resulted in a 4-log reduction of MRSA without elimination of the bacteria. The surviving bacteria within the biofilm were eliminated upon subsequent exposure to SAAP-148 and pexiganan but not with LL-37 ad ADEP4. Antibiotic treatment of mature biofilms on TAN discs followed by SAAP-148 also resulted in eradication of bacteria within the biofilm. SAAP-148 also fully eliminated bacteria within antibiotic-treated mature MRSA biofilms on an ex vivo liner of a prosthetic joint. Conclusions. A novel mature biofilm model has been developed in which the efficacy of antimicrobial peptides against bacteria, including persisters, residing within a biofilm was investigated. SAAP-148 and pexiganan were highly effective against the bacteria residing in antibiotic-exposed mature MRSA biofilms. This in vitro model system will be used to analyze the effects of novel antibiotic strategies and other anti-PJI agents

Aim. Septic arthritis (SA) is considered a medical emergency. The most common etiological agents are glucose consuming bacteria, so we evaluated the clinical utility of synovial fluid (SF) glucose levels and other biochemical parameters for supporting the diagnosis of the disease and their association with a positive bacteria culture and joint destruction. Methods. Adult patients with SA diagnose were enrolled prospectively between July 2018 and October 2019. As control group, adults with knee osteoarthritis, meniscus and/or knee ligaments lesions were enrolled. SF samples were obtained from the joints by arthrocentesis/arthrotomy. Microbiological analyses of SF were performed using Brucella broth blood culture flasks, samples were incubated at 37°C with 5% CO. 2. for 24 hours. Gram stain, chocolate and blood agar were used for the identification and growth of the bacteria. SF glucose levels, pH and leukocyte esterase were measured as biochemical parameters using a glucometer and colorimetric test strips. The Outerbridge classification was used for grading the osteochondral injury. Furthermore, blood samples were collected from patients and control subjects for determining glucose levels. Results. We included 8 subjects with knee ligaments lesions, 6 with meniscus lesions and 5 with osteoarthritis as control group, as well as 20 patients with SA diagnose. The mean age of the patients was 57.8 years with a 65% of male predominance. The most common affected joint was the knee (85%). SF culture was positive in 60% of the cases and the most common etiological agent was Staphylococcus aureus (58.3%). SF glucose levels from patients were lower than the controls (P=0.0018) and showed the lowest concentration in patients with a positive culture (P=0.0004). There was also a difference between blood and SF glucose concentration from the positive culture patients (P<0.0001). Leucocyte esterase presented the highest values in positive culture patients (P=<0.0001) and a more acidic pH was found compared to the control group (P<0.0001). Regarding the osteochondral injury, the lowest concentrations of SF glucose were found in patients with a higher grade in the classification (P = 0.0046). Conclusions. SF glucose and leukocyte esterase concentrations might be a quick and cheap useful parameter for the physician for distinguishing between bacterial infection and not infected joint. In addition, the lowest SF glucose levels might give information about the joint damage due to the disease

Aim. Currently, gram-negative bacteria (GNB), including multidrug-resistant (MDR-GNB) pathogens, are gaining importance in the aetiology of prosthetic joint infection (PJI). To characterize the antimicrobial resistance patterns of Gram-negative bacteria (GNB) causing hip prosthetic joint infections in elderly patients treated at a Brazilian tertiary academic hospital. Method. This is a retrospective, cross-sectional study of patients over 60 years of age undergoing hip arthroplasty from 2018 to 2023 at a tertiary academic trauma, which were diagnosed with hip prosthetic joint infection. PJI diagnosed was based on EBJIS criteria, in which intraoperative tissue cultures identified the pathogens. Demographics, reason for arthroplasty, type of implant and susceptibility patterns using disk diffusion method were analysed. Results. Overall, among 17 elderly patients diagnosed with hip infected arthroplasty, 45 bacterial isolated were identified. Debridement, irrigation, antibiotic and implant retention (DAIR) procedures due to uncontrolled infection occurred in 47.0% (n=8/17), and five patients underwent more than two DAIR surgeries. Tissue cultures yielded eleven different bacterial species, with GNB accounted for 64.4% (n=29/45) of pathogens. Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa were identified in 34.5% (n=10/29), 17.25% (n=5/29), 13.8% (n=4/29), and 13.8% (n=4/29), respectively. In the resistance profile analysis, E. coli was most sensitive to antibiotics, whereas K. pneumoniae showed resistance rates higher than 70% for cephalosporins, carbapenems, and quinolones. All A. baumannii isolates were resistant to meropenem, and 80% of these isolates were resistant to amikacin. Conclusions. This study emphasizes the role of GNB in the microbiological profile of PJI among elderly patients at a tertiary hospital in a Brazilian centre. The present study portrays a worryingly higher rates of MDR-GNB, mainly to quinolones and cephalosporins resistance which have been the cornerstone of PJI antibiotic treatment. In addition, higher rates carbapenems and aminoglycosides resistance shows a threat to antibiotic treatment of PJI. More global studies need to be carried out to show a likely change in the microbial epidemiology of PJI

Aims. The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI). Methods. Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polymethylmethacrylate (PMMA) or vancomycin powder. Results. A total of 19 patients with acute PJI after TKA were identified and 29 unique bacterial isolates were recovered. The mean time to revision was 37 days (6 to 84). Nine isolates (31%) were resistant to gentamicin, ten (34%) were resistant to tobramycin, and seven (24%) were resistant to vancomycin. Excluding one Fusobacterium nucleatum, which was resistant to all three antibiotics, all isolates resistant to tobramycin or gentamicin were susceptible to vancomycin and vice versa. Overall, 2.4 g of tobramycin hand-mixed into 80 g of PMMA and 1 g of intra-articular vancomycin powder consistently achieved concentrations above the minimum inhibitory concentrations of susceptible organisms. Conclusion. One-third of bacteria causing acute PJI after primary TKA were resistant to the aminoglycosides commonly mixed into PMMA, and one-quarter were resistant to vancomycin. With one exception, all bacteria resistant to tobramycin were susceptible to vancomycin and vice versa. Based on these results, the optimal cover for organisms causing most cases of acute PJI after TKA can be achieved with a combination of tobramycin mixed in antibiotic cement, and vancomycin powder. Cite this article: Bone Joint J 2020;102-B(6 Supple A):163–169

Title. Longitudinal Intravital Imaging to Quantify the “Race for the Surface” Between Host Immune Cell and Bacteria for Orthopaedic Implants with S. aureus Colonization in a Murine Model. Aim. To assess S. aureus vs. host cell colonization of contaminated implants vis intravital multiphoton laser scanning microscopy (IV-MLSM) in a murine model. Method. All animal experiments were approved by IACUC. A flat stainless steel or titanium L-shaped pin was contaminated with 10. 5. CFU of a red fluorescent protein (RFP) expressing strain of USA300LAC, and surgically implanted through the femur of global GFP-transgenic mice. IV-MLSM was performed at 2, 4, and 6 hours post-op. Parallel cross-sectional CFU studies were performed to quantify the bacteria load on the implant at 2,4,6,12,18 and 24 hours. Results. 1) We developed a high-fidelity reproducible IV-MLSM system to quantify S. aureus and host cell colonization of a bone implant in the mouse femur. Proper placement of all implants were confirmed with in vivo X-rays, and ex vivo photos. We empirically derive the ROI during each imaging session by aggregating the imaged volume which ranges from (636.4um × 636.4um × 151um) = 0.625 +/- 0.014 mm. 3. of bone marrow in a global GFP-transgenic mouse. 2) IV-MLSM imaging acquisition of the “race for the surface”.In vitro MPLSM images of implants partially coated with USA300LAC (RFP-MRSA) were verified by SEM image. Results from IV-MLSM of RFP-MRSA and GFP. +. host cell colonization of the contaminated implants illustrated the mutually exclusive surface coating at 3hrs, which to our knowledge is the first demonstration of “the race for the surface” between bacteria and host cells via intravital microscopy. 3) Quantifying the “race for the surface” with CFU verification of S. aureus on the implant. 3D volumetric rendering of the GFP. +. voxels and RFP+ voxels within the ROI were generated in Imaris. The voxel numbers suggeste that the fight for the surface concludes ∼3hrs post-infection, and then transitions to an aggressive MRSA proliferation phase. The results of WT control demonstrate a significant increase in CFU by 12hrs post-op for both stainless steel (P<0.01) and titanium (P<0.01). Conclusions. We developed IV-MLSM to quantify the “Race for the Surface” between host cells and contaminating S. aureus in a murine femur implant model. This race is remarkably fast, as the implant surface is completely covered with 3hrs, peak bacterial growth on the implant occurs between 2 and 12 hours and is complete by 12hrs

Aims. To investigate the efficacy of ethylenediaminetetraacetic acid-normal saline (EDTA-NS) in dispersing biofilms and reducing bacterial infections. Methods. EDTA-NS solutions were irrigated at different durations (1, 5, 10, and 30 minutes) and concentrations (1, 2, 5, 10, and 50 mM) to disrupt Staphylococcus aureus biofilms on Matrigel-coated glass and two materials widely used in orthopaedic implants (Ti-6Al-4V and highly cross-linked polyethylene (HXLPE)). To assess the efficacy of biofilm dispersion, crystal violet staining biofilm assay and colony counting after sonification and culturing were performed. The results were further confirmed and visualized by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). We then investigated the efficacies of EDTA-NS irrigation in vivo in rat and pig models of biofilm-associated infection. Results. When 10 mM or higher EDTA-NS concentrations were used for ten minutes, over 99% of S. aureus biofilm formed on all three types of materials was eradicated in terms of absorbance measured at 595 nm and colony-forming units (CFUs) after culturing. Consistently, SEM and CSLM scanning demonstrated that less adherence of S. aureus could be observed on all three types of materials after 10 mM EDTA-NS irrigation for ten minutes. In the rat model, compared with NS irrigation combined with rifampin (Ti-6Al-4V wire-implanted rats: 60% bacteria survived; HXLPE particle-implanted rats: 63.3% bacteria survived), EDTA-NS irrigation combined with rifampin produced the highest removal rate (Ti-6Al-4V wire-implanted rats: 3.33% bacteria survived; HXLPE particle-implanted rats: 6.67% bacteria survived). In the pig model, compared with NS irrigation combined with rifampin (Ti-6Al-4V plates: 75% bacteria survived; HXLPE bearings: 87.5% bacteria survived), we observed a similar level of biofilm disruption on Ti-6Al-4V plates (25% bacteria survived) and HXLPE bearings (37.5% bacteria survived) after EDTA-NS irrigation combined with rifampin. The in vivo study revealed that the biomass of S. aureus biofilm was significantly reduced when treated with rifampin following irrigation and debridement, as indicated by both the biofilm bacterial burden and crystal violet staining. EDTA-NS irrigation (10 mM/10 min) combined with rifampin effectively removes S. aureus biofilm-associated infections both in vitro and in vivo. Conclusion. EDTA-NS irrigation with or without antibiotics is effective in eradicating S. aureus biofilm-associated infection both ex and in vivo. Cite this article: Bone Joint Res 2024;13(1):40–51

Aim. Here we describe a cohort study to determine the performance of a commercially available Fluorescence In Situ Hybridization (FISH)-kit on samples of 65 consecutive patients suspected of orthopedic implant associated infections (IAI). Culture is routinely used and has a high specificity and sensitivity but requires days to more than a week for slow growing bacteria. FISH results are available within 45–60 minutes and thus specific treatment can start immediately. In addition, previous antibiotic therapy may hinder culture while bacteria may still be detected by FISH. Method. The hemoFISH-kit from Miacom diagnostics (Dusseldorf, Germany) was used on a total of 82 joint aspirates, sonication fluids and tissue samples of 65 consecutive patients to detect and identify possible microorganisms. This FISH-kit contains a universal 16S rRNA probe and species-specific probes for bacteria commonly encountered in blood infections. FISH and culture were compared to the clinical definition of IAI. These definitions were based on the criteria described by Pro-Implant Foundation criteria for IAI after fracture fixation or prosthetic joint infection. If no criteria were described in the literature for a specific IAI then MSIS criteria were used. Results. FISH and culture was done in 33 plain tissue samples, 43 sonication fluid samples and 6 joint aspirates of 65 patients. Results are shown in table 1. In clinical infections FISH provided earlier results in 7 and 2 extra for culture-negative. In 5 IAI-negative cases FISH was false-positive. Conclusions. Faster diagnosis by FISH is appealing, however with a PPV of 64% the hemoFISH-kit is not accurate enough for clinical use. Also, blood and orthopedic infections have different common pathogens, therefor FISH could not identify all of the bacterial strains due to a lack of specific probes. An orthopedic FISH-kit could solve this problem

Objectives. Irrigation is the cornerstone of treating skeletal infection by eliminating pathogens in wounds. A previous study shows that irrigation with normal saline (0.9%) and ethylenediaminetetraacetic acid (EDTA) could improve the removal of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) compared with normal saline (NS) alone. However, it is still unclear whether EDTA solution is effective against infection with drug-resistant bacteria. Methods. We established three wound infection models (skin defect, bone-exposed, implant-exposed) by inoculating the wounds with a variety of representative drug-resistant bacteria including methicillin-resistant S. aureus (MRSA), extended spectrum beta-lactamase-producing E. coli (ESBL-EC), multidrug-resistant Pseudomonas aeruginosa (MRPA), vancomycin-resistant Enterococcus (VRE), multidrug-resistant Acinetobacter baumannii (MRAB), multidrug-resistant Enterobacter (MRE), and multidrug-resistant Proteus mirabilis (MRPM). Irrigation and debridement were repeated until the wound culture became negative. The operating times required to eliminate pathogens in wounds were compared through survival analysis. Results. Compared with other groups (NS, castile soap, benzalkonium chloride, and bacitracin), the EDTA group required fewer debridement and irrigation operations to achieve pathogen eradication in all three models of wound infection. Conclusion. Irrigation with EDTA solution was more effective than the other irrigation fluids used in the treatment of wound infections caused by drug-resistant pathogens. Cite this article: Z. Deng, F. Liu, C. Li. Therapeutic effect of ethylenediaminetetraacetic acid irrigation solution against wound infection with drug-resistant bacteria in a rat model: an animal study. Bone Joint Res 2019;8:189–198. DOI: 10.1302/2046-3758.85.BJR-2018-0280.R3

Aim. 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. Method. 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. Results. A total of 1673 patients were included, of whom 996 (60%) had a suspected PJI and 677 (40%) an osteoarticular infection without joint endoprosthesis (control group). In patients with suspected PJI the median age (standard deviation) was 67 (14) years; 407 (41%) were males. The anatomic location of the prosthesis was hip in 522 (52%) patients, knee in 437 (44%), megaprostheses in 14 (1%), shoulder in 8 (1%) and other endoprosthesis in 15 (2%) patients. In 437 (44%) of PJI cases pathogen(s) were detected, 271 (62%) were monomicrobial and 166 (38%) polymicrobial. Of 996 patients with suspected PJI, 2.4% (n = 24) had monomicrobial infections caused by bacteria belonging to the normal oral flora, predominantly oral streptococci (n = 21). In contrast, only 0.4% (n =3) of the control group without joint prosthesis had monomicrobial infections caused by oral bacteria. This difference was statistically significant (p = 0.002), whereas the patient age (p = 0.058) and the anatomic location of the joint prosthesis (p = 0.622) did not have any effect on the infections due to oral bacteria. Conclusions. The incidence of infections caused by oral bacteria was significantly higher in patients with endoprosthesis than in other osteoarticular infections (2.4% versus 0.4%). This finding indicates that joint prostheses are at risk of haematogenous PJI originating from oral cavity. Future prospective studies need to determine the exact risk of haematogenic PJI caused by oral bacteria, as well as the potential of preventing these infections by antibiotic prophylaxis

In the past decades, titanium-based biomaterials have been broadly used in maxillofacial and periodontology surgery. The main aetiological agents related to complications in this procedures are Porphyromonas gingivalis, a Gram-negative anaerobic bacteria that is also responsible for the development of chronic gingivitis, and Streptococcus oralis, a Gram positive facultative anaerobic bacteria. In previous studies, we have demonstrated that the fluorine doping of titanium-based alloys reduces bacterial adherence. The aim of this study is to evaluate the bacterial adherence on fluorine-doped titanium (TiF) probes compared to chemical polishing titanium (Ti) probes. The P. gingivalis ATCC 33277 and S. oralis ATCC 9811 adherence study was performed by introducing each probe in a well of 6-well plate with 5 ml containing 106 colony forming units (CFU/ml) in sterile 0.9% NaCl and was incubated 37°C 5% CO2 for 90 minutes, in anaerobiosis in the case of P. gingivalis. After incubation, samples were stained with LIVE/DEAD BacLight Bacterial Viability Kit. Proportion of live and dead bacteria was calculated and studied by using ImageJ software. The experiments were performed in triplicate. The statistical data were analyzed by nonparametric Wilcoxon test with a level of statistical significance of 0.05. Our results showed a significant (p<0.0053) 14.41% decrease of the adherence of P. gingivalis on TiF and an increase of 30% of dead cells. For S. oralis we did not get significant results. In conclusion, TiF can be considered a promising approach to prevent and treat infections related to maxillofacial and periodontology surgery

The passage of bacteria through surgical drapes is a potential cause of wound infection. Previous studies have shown that liquids and human albumin penetrate certain types of drapes. 12. We studied the passage of bacteria through seven different types of surgical drape and an operating tray. We also studied the effect of different wetting agents on the passage of bacteria through wet reusable woven drapes. Bacteria were grown on an overfilled whole horse blood agar plate. The plate was covered with the drape to be tested and a second agar plate was inverted and placed on the drape. After 30 minutes the second agar plate was removed, incubated and inspected for bacterial growth. The experiment was repeated removing the second plate at 60 minutes and then again at 90 minutes. The entire experiment was repeated for each drape and then for each wetting agent. Bacteria easily penetrated all the woven reusable fabrics within 30 minutes. The disposable non-woven drapes proved to be impermeable up to 90 minutes, as did the operating tray. Chlorhexidine and Povidone-Iodine were demonstrated to slow, but not stop the passage of bacteria through reusable woven drapes. Normal saline and human blood accelerated the passage of bacteria through reusable woven drapes. We recommend the use of non-woven disposable drapes or woven drapes with an impermeable operating tray, in all surgical cases

Aims. Bacteriophages infect, replicate inside bacteria, and are released from the host through lysis. Here, we evaluate the effects of repetitive doses of the Staphylococcus aureus phage 191219 and gentamicin against haematogenous and early-stage biofilm implant-related infections in Galleria mellonella. Methods. For the haematogenous infection, G. mellonella larvae were implanted with a Kirschner wire (K-wire), infected with S. aureus, and subsequently phages and/or gentamicin were administered. For the early-stage biofilm implant infection, the K-wires were pre-incubated with S. aureus suspension before implantation. After 24 hours, the larvae received phages and/or gentamicin. In both models, the larvae also received daily doses of phages and/or gentamicin for up to five days. The effect was determined by survival analysis for five days and quantitative culture of bacteria after two days of repetitive doses. Results. In the haematogenous infection, a single combined dose of phages and gentamicin, and repetitive injections with gentamicin or in combination with phages, resulted in significantly improved survival rates. In the early-stage biofilm infection, only repetitive combined administration of phages and gentamicin led to a significantly increased survival. Additionally, a significant reduction in number of bacteria was observed in the larvae after receiving repetitive doses of phages and/or gentamicin in both infection models. Conclusion. Based on our results, a single dose of the combination of phages and gentamicin is sufficient to prevent a haematogenous S. aureus implant-related infection, whereas gentamicin needs to be administered daily for the same effect. To treat early-stage S. aureus implant-related infection, repetitive doses of the combination of phages and gentamicin are required. Cite this article: Bone Joint Res 2024;13(8):383–391

Aims. Arthroplasty surgery of the knee and hip is performed in two to three million patients annually. Periprosthetic joint infections occur in 4% of these patients. Debridement, antibiotics, and implant retention (DAIR) surgery aimed at cleaning the infected prosthesis often fails, subsequently requiring invasive revision of the complete prosthetic reconstruction. Infection-specific imaging may help to guide DAIR. In this study, we evaluated a bacteria-specific hybrid tracer (. 99m. Tc-UBI. 29-41. -Cy5) and its ability to visualize the bacterial load on femoral implants using clinical-grade image guidance methods. Methods. 99m. Tc-UBI. 29-41. -Cy5 specificity for Stapylococcus aureus was assessed in vitro using fluorescence confocal imaging. Topical administration was used to highlight the location of S. aureus cultured on femoral prostheses using fluorescence imaging and freehand single photon emission CT (fhSPECT) scans. Gamma counting and fhSPECT were used to quantify the bacterial load and monitor cleaning with chlorhexidine. Microbiological culturing helped to relate the imaging findings with the number of (remaining) bacteria. Results. Bacteria could be effectively stained in vitro and on prostheses, irrespective of the presence of biofilm. Infected prostheses revealed bacterial presence on the transition zone between the head and neck, and in the screw hole. Qualitative 2D fluorescence images could be complemented with quantitative 3D fhSPECT scans. Despite thorough chlorhexidine treatments, 28% to 44% of the signal remained present in the locations of the infection that were identified using imaging, which included 500 to 2,000 viable bacteria. Conclusion. The hybrid tracer . 99m. Tc-UBI. 29-41. -Cy5 allowed effective bacterial staining. Qualitative real-time fluorescence guidance could be effectively combined with nuclear imaging that enables quantitative monitoring of the effectiveness of cleaning strategies. Cite this article: Bone Joint Res 2023;12(1):72–79

Prosthetic joint infection is one of the most challenging complications of joint alloplasty and the diagnosis remains difficult. The aim of the study was to investigate the bacterial flora in surgical samples from 22 prosthetic patients using a panel of culture-independent molecular methods including broad range 16S rRNA gene PCR, cloning, sequencing, phylogeny, quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH). Concomitant samples were cultured by standard methods. Molecular methods detected presence of bacteria in samples from 12 of 22 patients. Using clone libraries a total of 40 different bacterial species were identified including known pathogens and species not previously described in association with prosthetic joint infections. The predominant species were Propionibacterium acnes and Staphylococcus epidermidis; polymicrobial infections were found in 9 patients. Culture-based methods showed bacterial growth in 8 cases with the predominant species being S. epidermidis. Neither anaerobic bacteria (including P. acnes) nor any of the species not previously described in implant infections were isolated. Additionally, 7 of the 8 culture positive cases were monomicrobial. Overall, the results of culture-based and molecular methods showed concordance in 11 cases (hereof 9 negative by both methods) and discrepancy in 6 cases. In the remaining 5 cases, culture-based methods identified only one species or a group of bacteria (e.g., coagulase negative staphylococci or coryneform rods), while culture-independent molecular methods were able to detect several distinct bacterial species including a species within the group identified by culture. A qPCR assay was developed to assess the abundance of Propionibacterium while S. aureus was quantified by a published S. aureus qPCR assay. These quantifications confirmed the findings from the clone library approach and showed the potential of qPCR for fast detection of bacteria in orthopedic samples. Additionally, both single cells and microcolonies were visualized using FISH and confocal scanning laser microscopy. In conclusion, the molecular methods detected a more diverse bacterial flora in prosthetic joint infections than revealed by standard culture-based methods, and polymicrobial infections were more frequently observed. The pathogenesis of these microorganisms and their role in implant-associated infections needs to be determined