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Macrophages and osteocytes are important regulators of inflammation, osteogenesis and osteoclastogenesis. However, their interactions under adverse conditions, such as biomaterial-associated infection (BAI) are not fully understood. We aimed to elucidate how factors released from macrophages modulate osteocyte responses in an in vitro indirect 3D co-culture model. Human monocyte-derived macrophages were cultured on etched titanium disks and activated with either IL-4 cytokine (anti-inflammatory M2 phenotype) or Staphylococcus aureus secreted virulence factors to simulate BAI (pro-inflammatory M1 phenotype). Primary osteocytes in collagen gels were then stimulated with conditioned media (CM) from these macrophages. The osteocyte response was analyzed by gene expression, protein secretion, and immunostaining. M1 phenotype macrophages were confirmed by IL-1β and TNF-α secretion, and M2 macrophages by ARG-1 and MRC-1.Osteocytes receiving M1 CM revealed bone inhibitory effects, denoted by reduced secretion of bone formation osteocalcin (BGLAP) and increased secretion of the bone inhibitory sclerostin (SOST). These osteocytes also downregulated the pro-mineralization gene PHEX and upregulated the anti-mineralization gene MEPE. Additionally, exhibited pro-osteoclastic potential by upregulating pro-osteoclastic gene RANKL expression. Nonetheless, M1-stimulated osteocytes expressed a higher level of the potent pro-osteogenic factor BMP-2 in parallel with the downregulation of the bone inhibitor genes DKK1 and SOST, suggesting a compensatory feedback mechanisms. Conversely, M2-stimulated osteocytes mainly upregulated anti-osteoclastic gene OPG expression, suggesting an anti-catabolic effect. Altogether, our findings demonstrate a strong communication between M1 macrophages and osteocytes under M1 (BAI)-simulated conditions, suggesting that the BAI adverse effects on osteoblastic and osteoclastic processes in vitro are partly mediated via this communication. STATEMENT OF SIGNIFICANCE: Biomaterial-associated infections are major challenges and the underlying mechanisms in the cellular interactions are missing, especially among the major cells from the inflammatory side (macrophages as the key cell in bacterial clearance) and the regenerative side (osteocyte as main regulator of bone). We evaluated the effect of macrophage polarization driven by the stimulation with bacterial virulence factors on the osteocyte function using an indirect co-culture model, hence mimicking the scenario of a biomaterial-associated infection. The results suggest that at least part of the adverse effects of biomaterial associated infection on osteoblastic and osteoclastic processes in vitro are mediated via macrophage-to-osteocyte communication., Competing Interests: Declaration competing of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Technological and implant design advances have helped reduce the frequency of aseptic total joint arthroplasty failure, but periprosthetic joint infections (PJI) remain a clinical important problem with high patient morbidity. Misinterpreting PJI as aseptic mechanical loosening commonly leads to unsatisfactory revision arthroplasty, persistent infection, and poor long-term results. While there is no single "gold standard" diagnostic test for PJI, recent collaborative efforts by Orthopaedic and Infectious Disease Societies have developed algorithms for diagnosing PJI. However, the efficacy of individual tests as well as diagnostic thresholds are controversial. We review the recommended thresholds for commonly used screening tests as well as tissue histopathology and confirmatory tests to diagnose periprosthetic infection. We also update lesser-known laboratory tests, and we briefly summarize rapidly evolving molecular tests to diagnose periprosthetic infection. Pathologists hold a critical role in assisting with PJI diagnosis, maintaining laboratory test quality and interpreting test results. Collaboration between clinicians and pathologists is essential to provide optimal patient care and reduce the burden of PJI., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background Context: Bacterial infection of spinal instrumentation is a significant challenge in spinal fusion surgery. Although the intraoperative local application of powdered vancomycin is common practice for mitigating infection, the antimicrobial effects of this route of administration are short-lived. Therefore, novel antibiotic-loaded bone grafts as well as a reliable animal model to permit the testing of such therapies are needed to improve the efficacy of infection reduction practices in spinal fusion surgery., Purpose: This study aims to establish a clinically relevant rat model of spinal implant-associated infection to permit the evaluation of antimicrobial bone graft materials used in spinal fusion., Study Design: Rodent study of chronic spinal implant-associated infection., Methods: Instrumentation anchored in and spanning the vertebral bodies of L4 and L5 was inoculated with bioluminescent methicillin-resistant Staphylococcus aureus bacteria (MRSA). Infection was monitored using an in vivo imaging system (IVIS) for 8 weeks. Spines were harvested and evaluated histologically, and colony-forming units (CFUs) were quantified in harvested implants and spinal tissue., Results: Postsurgical analysis of bacterial infection in vivo demonstrated stratification between MRSA and phosphate-buffered saline (PBS) control groups during the first 4 weeks of the 8-week infection period, indicating the successful establishment of acute infection. Over the 8-week chronic infection period, groups inoculated with 1 × 10 5 MRSA CFU and 1 × 10 6 MRSA CFU demonstrated significantly higher bioluminescence than groups inoculated with PBS control (p = 0.009 and p = 0.041 respectively). Histological examination at 8 weeks postimplantation revealed the presence of abscesses localized to implant placement in all MRSA inoculation groups, with the most pervasive abscess formation in samples inoculated with 1 × 10 5 MRSA CFU and 1 × 10 6 MRSA CFU. Quantification of CFU plated from harvested spinal tissue at 8 weeks post-implantation revealed the 1 × 10 5 MRSA CFU inoculation group as the only group with a significantly greater average CFU count compared to PBS control (p = 0.017). Further, CFU quantification from harvested spinal tissue was greater than CFU quantification from harvested implants across all inoculation groups., Conclusion: Our model demonstrated that the inoculation dosage of 1 × 10 5 MRSA CFU exhibited the most robust chronic infection within instrumented vertebral bodies. This dosage had the greatest difference in bioluminescence signal from control (p < 0.01), the lowest mortality (0% compared to 50% for samples inoculated with 1 × 10 6 MRSA CFU), and a significantly higher amount of CFUs from harvested spine samples than CFUs from control harvested spine samples. Further, histological analysis confirmed the reliability of this novel rodent model of implanted-associated infection to establish infection and biofilm formation of MRSA for all inoculation groups., Clinical Significance: This model is intended to simulate the infection of instrumentation used in spinal fusion surgeries concerning implant locality and material. This model may evaluate potential antimicrobial and osteogenic biomaterials and investigate the relationship between implant-associated infection and failed fusion., Competing Interests: Declarations of competing interests Dr. Witham is a medical advisory board member and investor in Augmedics, Inc. He has received grant support from the Gordon and Marilyn Macklin Foundation. Dr. Archer has received previous grant support from Pfizer and Boehringer Ingelheim and is a paid consultant for Janssen Pharmaceuticals. One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The preoperative diagnosis of infection during joint arthroplasty is important for clinical management. However, the evaluation of polymorphonuclear leukocytes (PMNs) during frozen section analysis is sometimes difficult due to frozen artifacts. In the present study, we sought to investigate the utility of intraoperative fresh frozen section (FFS) examination for diagnosis of infection and to evaluate whether the neutrophil-specific surface marker CD66b helps to improve the diagnostic accuracy of infection. A consecutive series of 65 original frozen sections at the time of resection arthroplasty was retrospectively reviewed compared with corresponding permanent sections. The presence of PMNs was determined using intraoperative FFS and permanent sections. Furthermore, CD66b staining was performed to identify PMNs clearly. The ratio of male to female patients was 21:42. The mean age was 70 years. Postoperatively, 25 of 65 cases were histologically diagnosed with infection (25/65; 39%). The sensitivity and specificity of intraoperative FFS relative to permanent section histology were 100% (25/25) and 95% (38/40), respectively. Among 40 patients without infection, two showed false-positive results during intraoperative FFS diagnosis (2/40, 5%). In addition, on CD66b staining, six cases (9%) experienced changes in results, which altered the sensitivity and specificity of intraoperative FFS compared with permanent histology only to 87% and 87%, respectively. In conclusion, the diagnostic performance of intraoperative FFS is high and comparable to yields of permanent section histology. Therefore, intraoperative FFS is highly suitable diagnostic method for detection of infection during joint arthroplasty. And CD66b immunostaining facilitates delicate identification of PMNs, especially in equivocal cases.

16S rRNA gene sequencing of DNA extracted from clinically uninfected hip and knee implant samples has revealed polymicrobial populations. However, previous studies assessed 16S rRNA gene sequencing as a technique for the diagnosis of periprosthetic joint infections, leaving the microbiota of presumed aseptic hip and knee implants largely unstudied. These communities of microorganisms might play important roles in aspects of host health, such as aseptic loosening. Therefore, this study sought to characterize the bacterial composition of presumed aseptic joint implant microbiota using next generation 16S rRNA gene sequencing, and it evaluated this method for future investigations. 248 samples were collected from implants of 41 patients undergoing total hip or knee arthroplasty revision for presumed aseptic failure. DNA was extracted using two methodologies-one optimized for high throughput and the other for human samples-and amplicons of the V4 region of the 16S rRNA gene were sequenced. Sequencing data were analyzed and compared with ancillary specific PCR and microbiological culture. Computational tools (SourceTracker and decontam) were used to detect and compensate for environmental and processing contaminants. Microbial diversity of patient samples was higher than that of open-air controls and differentially abundant taxa were detected between these conditions, possibly reflecting a true microbiota that is present in clinically uninfected joint implants. However, positive control-associated artifacts and DNA extraction methodology significantly affected sequencing results. As well, sequencing failed to identify Cutibacterium acnes in most culture- and PCR-positive samples. These challenges limited characterization of bacteria in presumed aseptic implants, but genera were identified for further investigation. In all, we provide further support for the hypothesis that there is likely a microbiota present in clinically uninfected joint implants, and we show that methods other than 16S rRNA gene sequencing may be ideal for its characterization. This work has illuminated the importance of further study of microbiota of clinically uninfected joint implants with novel molecular and computational tools to further eliminate contaminants and artifacts that arise in low bacterial abundance samples., Competing Interests: The authors have declared that no competing interests exist.

Objectives: In the microbiological diagnosis of periprosthetic joint infection (PJI), there is much discussion about the methodology of obtaining proper specimens, the processing technique, and suitable culture media. This retrospective study was conducted to analyse the accuracy of our culture techniques., Methods: Tissue samples and components from 258 patients after revision arthroplasty of the hip, knee, and shoulder were investigated, and the results of tissue cultures (TC) were compared to those of sonicate fluid cultures (SFC). Furthermore, an evaluation was performed of the influence of different culture media on the detection rate., Results: PJI was confirmed in 186 patients. The overall sensitivity of TC was no different to that of SFC (91.3% vs 90.8%, P = 1). In 153 cases (82.3%), TC and SFC showed concordant positive results. Results were discordant in 33 cases (17.7%). When differentiated according to the type of infection, TC showed significantly better results than SFC in detecting polymicrobial infections (97.0% vs 67.0%, P = 0.004). There were also significant differences between the culture media regarding the yield of microorganisms., Conclusions: TC was more effective in detecting co-infections. The best results were obtained using both TC and SFC. The choice of culture media has a significant influence on the quality of results., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Staphylococcus aureus is the predominant pathogen causing osteomyelitis. Unfortunately, no immunotherapy exists to treat these very challenging and costly infections despite decades of research, and numerous vaccine failures in clinical trials. This lack of success can partially be attributed to an overreliance on murine models where the immune correlates of protection often diverge from that of humans. Moreover, S. aureus secretes numerous immunotoxins with unique tropism to human leukocytes, which compromises the targeting of immune cells in murine models. To study the response of human immune cells during chronic S. aureus bone infections, we engrafted non-obese diabetic (NOD)- scid IL2Rγ null (NSG) mice with human hematopoietic stem cells (huNSG) and analyzed protection in an established model of implant-associated osteomyelitis. The results showed that huNSG mice have increases in weight loss, osteolysis, bacterial dissemination to internal organs, and numbers of Staphylococcal abscess communities (SACs), during the establishment of implant-associated MRSA osteomyelitis compared to NSG controls ( p < 0.05). Flow cytometry and immunohistochemistry demonstrated greater human T cell numbers in infected versus uninfected huNSG mice ( p < 0.05), and that T-bet + human T cells clustered around the SACs, suggesting S. aureus -mediated activation and proliferation of human T cells in the infected bone. Collectively, these proof-of-concept studies underscore the utility of huNSG mice for studying an aggressive form of S. aureus osteomyelitis, which is more akin to that seen in humans. We have also established an experimental system to investigate the contribution of specific human T cells in controlling S. aureus infection and dissemination., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Muthukrishnan, Wallimann, Rangel-Moreno, Bentley, Hildebrand, Mys, Kenney, Sumrall, Daiss, Zeiter, Richards, Schwarz and Moriarty.)

Osteomyelitis is a devastating complication of orthopaedic surgery and commonly caused by Staphylococcus aureus (S. aureus) and Group B Streptococcus (GBS, S. agalactiae). Clinically, S. aureus osteomyelitis is associated with local inflammation, abscesses, aggressive osteolysis, and septic implant loosening. In contrast, S. agalactiae orthopaedic infections generally involve soft tissue, with acute life-threatening vascular spread. While preclinical models that recapitulate the clinical features of S. aureus bone infection have proven useful for research, no animal models of S. agalactiae osteomyelitis exist. Here, we compared the pathology caused by these bacteria in an established murine model of implant-associated osteomyelitis. In vitro scanning electron microscopy and CFU quantification confirmed similar implant inocula for both pathogens (~10 5 CFU/pin). Assessment of mice at 14 days post-infection demonstrated increased S. aureus virulence, as S. agalactiae infected mice had significantly greater body weight, and fewer CFU on the implant and in bone and adjacent soft tissue (p < 0.05). X-ray, µCT, and histologic analyses showed that S. agalactiae induced significantly less osteolysis and implant loosening, and fewer large TRAP + osteoclasts than S. aureus without inducing intraosseous abscess formation. Most notably, transmission electron microscopy revealed that although both bacteria are capable of digesting cortical bone, S. agalactiae have a predilection for colonizing blood vessels embedded within cortical bone while S. aureus primarily colonizes the osteocyte lacuno-canalicular network. This study establishes the first quantitative animal model of S. agalactiae osteomyelitis, and demonstrates a vasculotropic mode of S. agalactiae infection, in contrast to the osteotropic behavior of S. aureus osteomyelitis., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Implant-associated infections are challenging to diagnose and treat. Fluorescent probes have been heralded as a technologic advancement that can improve our ability to non-invasively identify infecting organisms, as well as guide the inexact procedure of surgical debridement. This study's purpose was to compare two fluorescent probes for their ability to localize Staphylococcus aureus biofilm infections on spinal implants utilizing noninvasive optical imaging, then assessing the broader applicability of the more successful probe in other infection animal models. This was followed by real-time, fluorescence image-guided surgery to facilitate debridement of infected tissue. The two probe candidates, a labelled antibiotic that targets peptidoglycan (Vanco-800CW), and the other, a labelled antibody targeting the immunodominant Staphylococcal antigen A (1D9-680), were injected into mice with spine implant infections. Mice were then imaged noninvasively with near infrared fluorescent imaging at wavelengths corresponding to the two probe candidates. Both probes localized to the infection, with the 1D9-680 probe showing greater fidelity over time. The 1D9-680 probe was then tested in mouse models of shoulder implant and allograft infection, demonstrating its broader applicability. Finally, an image-guided surgery system which superimposes fluorescent signals over analog, real-time, tissue images was employed to facilitate debridement of fluorescent-labelled bacteria.

Background: Implant loosening - either infectious or aseptic- is a still a major complication in the field of orthopaedic surgery. In both cases, a pro-inflammatory peri-prosthetic environment is generated by the immune system - either triggered by bacteria or by implant wear particles - which leads to osteoclast differentiation and osteolysis. Since infectious cases in particular often require multiple revision surgeries, we wondered whether commonly used surgical suture material may also activate the immune system and thus contribute to loss of bone substance by generation of osteoclasts. Methods: Tissue samples from patients suffering from infectious implant loosening were collected intraoperatively and presence of osteoclasts was evaluated by histopathology and immunohistochemistry. Further on, human monocytes were isolated from peripheral blood and stimulated with surgical suture material. Cell supernatant samples were collected and ELISA analysis for the pro-inflammatory cytokine IL-8 was performed. These experiments were additionally carried out on ivory slices to demonstrate functionality of osteoclasts. Whole blood samples were incubated with surgical suture material and up-regulation of activation-associated cell surface markers CD11b and CD66b on neutrophils was evaluated by flow cytofluorometry analysis. Results: We were able to demonstrate that multinucleated giant cells form in direct vicinity to surgical suture material. These cells stained positive for cathepsin K, which is a typical protease found in osteoclasts. By in vitro analysis, we were able to show that monocytes differentiated into osteoclasts when stimulated with surgical suture material. Resorption pits on ivory slices provided proof that the osteoclasts were functional. Release of IL-8 into cell supernatant was increased after stimulation with suture material and was further enhanced if minor amounts of bacterial lipoteichoic acid (LTA) were added. Neutrophils were also activated by surgical suture material and up-regulation of CD11b and CD66b could be seen. Conclusion: We were able to demonstrate that surgical suture material induces a pro-inflammatory response of immune cells which leads to osteoclast differentiation, in particular in combination with bacterial infection. In conclusion, surgical suture material -aside from bacteria and implant wear particles- is a contributing factor in implant loosening., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Periprosthetic joint infection (PJI) is a devastating complication after arthroplasty. Prompt establishment of an infection diagnosis is critical but can be very challenging at present. In order to evaluate the diagnostic accuracy of alpha-defensin or leukocyte esterase for PJI, we performed systematic research in PubMed, Embase, and Cochrane Library to retrieve relevant studies. Data extraction and quality assessment were performed by two reviewers independently. A total of thirty-one eligible studies were finally included in the quantitative analysis. The pooled sensitivity and specificity of alpha-defensin (21 studies) for the diagnosis of PJI were 0.89 (95% confidence interval (CI), 0.83 to 0.93) and 0.96 (95% CI, 0.95 to 0.97), respectively. The value of the pooled diagnostic odds ratios (DOR) of alpha-defensin for PJI was 209.14 (95% CI, 97.31 to 449.50), and the area under the curve (AUC) was 0.98 (95% CI, 0.96 to 0.99). The pooled sensitivity and specificity of leukocyte esterase (17 studies) for the diagnosis of PJI were 0.90 (95% CI, 0.84 to 0.95) and 0.96 (95% CI, 0.93 to 0.97), respectively. The value of the DOR of leukocyte esterase for PJI was 203.23 (95% CI, 96.14 to 429.61), and the AUC was 0.98 (95% CI, 0.96 to 0.99). Based on the results of our meta-analysis, we can conclude that alpha-defensin and leukocyte esterase are valuable synovial fluid markers for identifying PJI with comparable high diagnostic accuracy., Competing Interests: The authors declare that they have no competing interests., (Copyright © 2020 Zhizhuo Li et al.)

Particles released from implants cause inflammatory bone loss, which is a key factor in aseptic loosening, the most common reason for joint replacement failure. With the anticipated increased incidence of total joint replacement in the next decade, implant failure will continue to burden patients. The gut microbiome is increasingly recognized as an important factor in bone physiology, however, its role in implant loosening is currently unknown. We tested the hypothesis that implant loosening is associated with changes in the gut microbiota in a preclinical model. When the particle challenge caused local joint inflammation, decreased peri-implant bone volume, and decreased implant fixation, the gut microbiota was affected. When the particle challenge did not cause this triad of local effects, the gut microbiota was not affected. Our results suggest that cross-talk between these compartments is a previously unrecognized mechanism of failure following total joint replacement., (© 2020 Federation of American Societies for Experimental Biology.)

Background: Patients with prosthetic heart valves (PHV) are at an increased risk of endocarditis and dysfunction. Knowledge about the etiology of dysfunction and extent of endocarditis can have distinct treatment implications. Echocardiography has limitations due to PHV-related artifacts. We hypothesized that computed tomography (CT) will have incremental value over echocardiography for evaluation of PHV abnormalities with surgical findings as the reference standard., Methods: Consecutive patients with PHV that had a reoperation for valve replacement, had a contrast chest CT and echocardiogram within 1 year of the reoperation, between 2010 and 2018 at a single academic center formed the study cohort. CTs and echocardiograms were assessed for potential etiologies of dysfunction (valve degeneration, pannus and thrombus); and for extent of endocarditis (vegetation, abscess, and pseudoaneurysm)., Results: Seventy-three patients (65.8% male, mean age 62.1 ± 16.5 years) formed the study cohort. The indication for reoperation was PHV dysfunction in 51 and PHV endocarditis in 22. Compared to echocardiography, CT diagnosed the etiology of PHV dysfunction in 17 (33.3%) more patients (9 valve degeneration, 8 pannus). In the PHV endocarditis cohort, CT failed to detect one vegetation and one abscess, whereas echocardiography failed to detect 1 abscess. In combination, CT and echocardiography demonstrated all the vegetations and abscesses., Conclusion: CT may provide superior characterization in comparison to echocardiography for the identification of the cause of prosthetic valve dysfunction, and complementary information to echocardiography for the evaluation of prosthetic valve endocarditis., (© 2020 Wiley Periodicals LLC.)

Aims: To evaluate the histopathological examination of peri-implant tissue samples as a technique in the diagnosis of postoperative spinal implant infection (PSII)., Methods: This was a retrospective analysis. Patients who underwent revision spinal surgery at our institution were recruited for this study. PSII was diagnosed by clinical signs, histopathology, and microbiological examination of intraoperatively collected samples. Histopathology was defined as the gold standard. The sensitivity for histopathology was calculated. A total of 47 patients with PSII and at least one microbiological and histopathological sample were included in the study., Results: PSII occurred in approximately 28% of the study population. Histopathology showed a sensitivity of 51.1% in the diagnosis of PSII. The most commonly found pathogens were Cutibacterium acnes and gram-positive staphylococci ., Conclusion: Histopathology has low sensitivity for detecting PSII. In particular, infections caused by low-virulence microorganisms are insufficiently detected by histopathology. Cite this article: Bone Joint J 2020;102-B(7):899-903.

Self-assembled peptide gels have generated interest as antibacterial materials to prevent biomaterial-related infections but these peptides are often associated with poor proteolytic stability. Efforts have been made to stabilize peptides by incorporating non-natural amino acids and/or linkages but complexation with polymers have not been explored. Therefore, we developed self-assembled peptide/chitosan gels, Boc-D-Phe-γ 4 -L-Phe-PEA (NH007)/chitosan and Boc-L-Phe-γ 4 -L-Phe-PEA (NH009)/chitosan, by complexing dipeptide NH007 or NH009 with chitosan in DMSO:acetic acid. The gels were characterized using SEM, FTIR, contact angle, and rheology data and found to exhibit excellent viscoelastic and self-healing characteristics. Complexation with chitosan led to an increase in stability against proteolytic degradation. Peptide/chitosan gels showed broad spectrum antibacterial activities against Gram-negative and Gram-positive bacteria, such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis at a high inoculum of 10 7 -10 8  cfu/mL. NH007/chitosan gels showed 70-75% inhibition, whereas NH009/chitosan showed 78-81% inhibition and NH009/chitosan gels, in particular, showed strong antibacterial activity against pathogenic strain of P. aeruginosa. A unique feature of these gels is that the antibacterial activities did not decrease gradually but were sustained for up to 48 h. The mechanistic studies using SEM and HR-TEM indicated interaction of gels with bacterial membrane components, leading to cell lysis. The MTT and LDH assays indicated >90% cell viability and only 8-10% toxicity towards NIH 3T3 fibroblast cells. Thus, peptide/chitosan gels developed in the present work showed improved proteolytic stability and sustained antibacterial activities and, therefore, may be used for preventing biomaterial-related infections., Competing Interests: Declaration of competing interest Authors declare no competing financial interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Implant associated infections can result in devastating consequences for patients. One major cause is the formation of bacterial biofilms, which result in increased resistance against antimicrobial therapeutics. A reduction of implant associated infections can be achieved by functionalization of implant surfaces. The generation of three dimensional surface structures by femtosecond laser ablation is one method to fabricate bacterial repellent large scaled surfaces without altering the material chemical composition. The challenge is to reduce bacterial growth while improving cellular ongrowth. For this purpose, spike structures were created as small as possible by used fabrication method on cubic Ti90/Al6/V4-rods and their effectiveness against bacterial colonization was compared to unstructured Ti90/Al6/V4-rods. Rods were implanted in the rat tibia and infected intraoperatively with 10 3  CFU of Staphylococcus aureus. Besides clinical behaviour and lameness, the vital bacterial biomass, morphological appearance and the volume of eukaryotic cells were determined on the implant surface after 21 days. Bone alterations were examined by radiological and histological techniques. Unexpectedly, the laser-structured implants did not show a lower bacterial load on the implant surface and less severe infection related bone and tissue alterations compared to the group without structuring. Simultaneously, a better bony integration and a higher cellular colonization with eukaryotic cells was detected on the laser-structured implants. These findings don't support the previous in vitro results. Nevertheless, the strong integration into the bone is a powerful argument for further surface modifications focussing on the improvement of the antibacterial effect. Additionally, our results underline the need for in vivo testing of new materials prior to clinical use., Competing Interests: Disclosures The authors declare that they have no competing interests. Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2019 Elsevier B.V. All rights reserved.)

With its high temporal and spatial resolution and relatively low radiation exposure, positron emission tomography (PET) is increasingly being used in the management of cardiac patients, particularly those with inflammatory cardiomyopathies such as sarcoidosis. This review discusses the role of PET imaging in assessing myocardial viability, inflammatory cardiomyopathies, and endocarditis; describes the different protocols needed to acquire images for specific imaging tests; and examines imaging interpretation for each image dataset-including identification of the mismatch defect in viability imaging, which is associated with significant improvement in LV function after revascularization. We also review the role of fluorodeoxyglucose PET in cardiac sarcoidosis diagnosis, the complementary role of magnetic resonance imaging in inflammatory cardiomyopathy, and the emerging use of cardiac PET in prosthetic valve endocarditis., Competing Interests: Conflict of Interest Disclosure: The authors have completed and submitted the Methodist DeBakey Cardiovascular Journal Conflict of Interest Statement and none were reported., (© 2020 Houston Methodist Hospital Houston, Texas.)

Despite its presence in orthopaedic infections, Staphylococcus epidermidis's ability to directly induce inflammation and bone destruction is unknown. Thus, we compared a clinical strain of methicillin-resistant biofilm-producing S. epidermidis (RP62A) to a highly virulent and osteolytic strain of methicillin-resistant Staphylococcus aureus (USA300) in an established murine implant-associated osteomyelitis model. Bacterial burden was assessed by colony forming units (CFUs), tissue damage was assessed by histology and micro-computed tomography, biofilm was assessed by scanning electron microscopy (SEM), host gene expression was assessed by quantitative polymerase chain reaction, and osseous integration was assessed via biomechanical push-out test. While CFUs were recovered from RP62A-contaminated implants and surrounding tissues after 14 days, the bacterial burden was significantly less than USA300-infected tibiae (p < 0.001). In addition, RP62A failed to produce any of the gross pathologies induced by USA300 (osteolysis, reactive bone formation, Staphylococcus abscess communities, marrow necrosis, and biofilm). However, fibrous tissue was present at the implant-host interface, and rigorous SEM confirmed the rare presence of cocci on RP62A-contaminated implants. Gene expression studies revealed that IL-1β, IL-6, RANKL, and TLR-2 mRNA levels in RP62A-infected bone were increased versus Sterile controls. Ex vivo push-out testing showed that RP62A-infected implants required significantly less force compared with the Sterile group (7.5 ± 3.4 vs. 17.3 ± 4.1 N; p < 0.001), but required 10-fold greater force than USA300-infected implants (0.7 ± 0.3 N; p < 0.001). Taken together, these findings demonstrate that S. epidermidis is a commensal pathogen whose mechanisms to inhibit osseous integration are limited to minimal biofilm formation on the implant, and low-grade inflammation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:852-860, 2020., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Orthopedic metal implants are notoriously associated with release of metallic ions able to cause biological adverse reactions which might lead to implant loosening and failure. To limit any possible adverse reactions, ceramic coatings for orthopedic metal implants have been introduced. However, information regarding the interaction of these coatings with microbes responsible for periprosthetic joint infections (PJIs) is lacking. Hence, the aim of the present in vitro study is to assess the microbial affinity to a titanium-niobium nitride (TiNbN) coating., Methods: Adhesion and biofilm formation of clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Cutibacterium acnes were assessed on TiNbN-coated titanium discs in comparison with uncoated titanium and cobalt-chrome alloys discs, with either smooth or rough surfaces. Bacterial adhesion was performed by counting adhered bacteria in the first hours of incubation, and the biofilm formation was performed by means of a spectrophotometric assay and by confocal laser scan microscopy after 72 hours of incubation., Results: Overall, Staphylococcus aureus and Staphylococcus epidermidis, among the most common bacteria responsible for PJIs, displayed a significantly decreased attachment in the first hours of contact and, when cultured in presence of TiNbN coating, in comparison with CoCrMo. Biofilm formation of the four tested strains was comparable on all alloys., Conclusions: Although the onset of a PJI is more complex than in an in vitro scenario, these findings suggest that TiNbN-coated orthopedic implants do not increase PJIs risk while ameliorating tribological and surface properties could represent a valid choice to limit possible complications such as metal hypersensitivity.

Identification of bacteria causing tissue infections can be comprehensive and, in the cases of non- or slow-growing bacteria, near impossible with conventional methods. Performing shotgun metagenomic sequencing on bacterial DNA extracted directly from the infected tissue may improve time to diagnosis and targeted treatment considerably. However, infected tissue consists mainly of human DNA (hDNA) which hampers bacterial identification. In this proof of concept study, we present a modified version of the Ultra-Deep Microbiome Prep kit for DNA extraction procedure, removing additional human DNA. Tissue biopsies from 3 patients with orthopedic implant-related infections containing varying degrees of Staphylococcus aureus were included. Subsequent DNA shotgun metagenomic sequencing using Oxford Nanopore Technologies' (ONT) MinION platform and ONTs EPI2ME WIMP and ARMA bioinformatic workflows for microbe and antibiotic resistance genes identification, respectively. The modified DNA extraction protocol led to an additional ~10-fold reduction of human DNA while preserving S. aureus DNA. Including the DNA sequencing and bioinformatics analyses, the presented protocol has the potential of identifying the infection-causing pathogen in infected tissue within 7 hours after biopsy. However, due to low number of S. aureus reads, positive identification of antibiotic resistance genes was not possible.

This retrospective study aimed to clarify the short- and mid-term outcomes of elderly patients who underwent surgery to treat left-sided native valve infective endocarditis (LSNIE). Between July 2005 and September 2015, 179 patients underwent surgical treatment for active LSNIE at a single institution. Patients were classified into two groups: ≥65 years (elderly group) and <65 years (non-elderly group). Clinical features, surgical information, postoperative complications, and three-year survival rates were compared. The average ages were 74.2 ± 6.4 and 45.2 ± 12.6 years in the elderly and non-elderly groups, respectively. The elderly group had a higher predicted mortality rate and a lower incidence of preoperative septic emboli-related complications. Echocardiographic assessments of infected valves were generally homogenous between the groups. The elderly patients had a higher in-hospital mortality rate than the non-elderly patients (26.3% vs. 5.7%, P = 0.001). For patients who survived to discharge, the three-year cumulative survival rates were 75.0% ± 8.2% and 81.2% ± 3.4% in the elderly and non-elderly groups, respectively (P = 0.484). In conclusion, elderly patients are at a higher risk of in-hospital mortality after surgery for LSNIE. However, once elderly patients are stabilized by surgical treatment and survive to discharge, the mid-term outcomes are promising.

Background: The data on infective endocarditis after transcatheter aortic valve implantation (TAVI) is scarce and limited to case reports and case series in the literature. It is the need of the hour to analyze the available data on post-TAVI infective endocarditis from the available literature. The objectives of this systematic review were to evaluate the incidence of infective endocarditis after transcatheter aortic valve implantation, its microbiological profile and clinical outcomes. It will help us to improve the antibiotic prophylaxis strategies and treatment options for infective endocarditis in the context of TAVI., Methods: EMBASE, Medline and the CENTRAL trials registry of the Cochrane Collaboration were searched for articles on infective endocarditis in post-TAVI patients till October 2018. Eleven articles were included in the systematic review. The outcomes assessed werethe incidence of infective endocarditis, its microbiological profile andclinical outcomes including major adverse cardiac event (MACE), net adverse clinical event (NACE), surgical intervention and valve-in-valve procedure., Results: The incidence of infective endocarditis varied from 0%-14.3% in the included studies, the mean was3.25%. The average duration of follow-up was 474 days (1.3 years). Enterococci were the most common causative organism isolated from 25.9% of cases followed by Staphylococcus aureus (16.1%) and coagulase-negative Staphylococcus species (14.7%). The mean in-hospital mortality and mortality at follow-up was 29.5% and 29.9%, respectively. The cumulative incidence of heart failure, stroke and major bleeding were 37.1%, 5.3% and 11.3%,respectively. Only a single study by Martinez-Selles et al. reported arrhythmias in 20% cases. The septic shock occurred in 10% and 27.7% post-TAVI infective endocarditis patients according to 2 studies. The surgical intervention and valve-in-valve procedure were reported in 11.4% and 6.4% cases, respectively., Conclusion: The incidence of post-TAVI infective endocarditis is low being 3.25% but it is associated with high mortality and complications. The most common complication is heart failure with a cumulative incidence of 37.1%. Enterococciare the most common causative organism isolated from 25.9% of cases followed by Staphylococcus aureus in 16.1% of cases. Appropriate measures should be taken to prevent infective endocarditis in post-TAVI patients including adequate antibiotics prophylaxis directed specifically against these organisms., Study Registration: PROSPERO registration number CRD42018115943., Competing Interests: The authors have declared that no competing interests exist.

Infection is a main cause of implant failure. Early implant-related infections often occur in the first 4 weeks post-operation. Inhibiting bacterial adhesion and biofilm formation at the early stage and promoting subsequent implant osseointegration are important for implant success. Our previous studies demonstrated that dimethylaminododecyl methacrylate (DMADDM) provided dental materials with antibacterial effects. In the present study, DMADDM and hydroxyapatite (HA) are loaded on to the titanium (Ti) surface via poly dopamine (PDA) self-polymerization. This local DMADDM-delivery Ti is referred as Ti-PHD. Here we report the two-staged capability of Ti-PHD: (1) in the first stage, releasing DMADDM during the high-infection-risk initial period post-implantation for 4 weeks; (2) then in the second stage, enhancing osteogenesis and promoting osseointegration. Ti-PHD has a porous surface with higher average roughness and greater hydrophilicity than pure Ti. Its biocompatibility is verified in vitro and in vivo. During the first 4 weeks of release, both DMADDM remaining on Ti surface and DMADDM released into the soaking medium greatly reduced the adherence and growth of pathogens. This is further confirmed by the prevention of bone destruction in a rat osteomyelitis model. After releasing DMADDM for 4 weeks, Ti-PHD promotes osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) and new bone formation around the implants in vivo. This article represents the first report on the two-staged, time-dependent antibacterial and osteogenesis effects of Ti-PHD, demonstrating its potential for clinical applications to inhibit implant-associated infections. STATEMENT OF SIGNIFICANCE: The present study develops a two-staged time-dependent system for local dimethylaminododecyl methacrylate (DMADDM) delivery via Ti implant (referred to as Ti-PHD). DMADDM and hydroxyapatite (HA) are loaded on to the Ti surface with poly dopamine (PDA). Ti-PHD can release DMADDM during the high-risk period of infection in the first stage, and then promote osseointegration and new bone formation in the second stage. This bioactive and therapeutic Ti is promising to inhibit infections and enhance implant success., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Objective: To evaluate the role of histologicalpathology in the diagnosis of periprosthetic joint infection. Methods: A total of 145 cases of joint arthroplasty during October 2017 and October 2018 from Beijing Jishuitan Hospital were collected. There were 23 cases of infection, including knee joint arthroplasty (12 cases) and hip arthroplasty (11 cases). There were 17 females and 6 males. Patients' age ranged from 39 to 76 years (mean 63 years). The infection was diagnosed if there were >5 neutrophils per high power field in at least 5 high power field. The permanent sections were examined twice separately by two pathologists, and the interval time of histologic examination was at least two weeks. Sensitivity (SE), specificity (SP), positive predictivevalue (PPV), and negative predictive value (NPV) were calculated. The consistency evaluation of histologic examination of two pathologists was calculated by Kappa analysis. Results: The neutrophil cells could locate scattered or focally in the synovium tissue of periprosthetic joint infection. Somewhere, the infiltration of vessel and the perivascular distribution could also exist. Opportunity coincidence rate between two pathologists was 91.3% (Kappa=0.817). The results showed that SE was 60.9%, SP was 100.0%, NPV was 93.1%, PPV was 100.0%. Conclusions: The presence of polymorphonuclear cells in histologic examination is correlated with infection. There was high consistency between histologic examination and clinical diagnosis of joint arthroplasty.

Background: Implant-related bone infections with methicillin-resistant Staphylococcus aureus (MRSA) remain a challenge for orthopedic surgeons. This devasting complication may lead to functional impairment and loss of the affected limbs. High failure rates in treatment make improvement of surgical treatment necessary. Beside an already established demanding and costly large animal model, a small animal model of a two-stage revision does not exist, yet. Thus, the purpose of this study was to establish a preclinical small animal model to simulate a two-stage revision in implant-related MRSA infection., Materials and Methods: In twelve rabbits Steel K-wires were implanted into the intramedullary canal of the left tibia, followed by inoculation with MRSA. Two different clinical isolates of MRSA-strains were used in two different concentrations (CFUs; 10 5 and 10 7 colony forming units (CFUs). This led to four groups of three rabbits each. Eleven rabbits survived the whole study period. After four weeks the inoculated K-wires were removed and replaced with vancomycin loaded PMMA-spacers (stage 1). Twenty-eight days later new K-wire implants were placed intramedullary (stage 2). After 84 days all animals were sacrificed. Tibiae were analyzed microbiologically, radiologically and histologically., Results: In every rabbit K-wire associated infection could be established within the first four weeks. After irrigation and debridement at revision one (stage 1), infection could be eradicated in 67% of group I, in 50% of group II and in 33% of group III and IV. Recurrence of the infection could be determined in all animals of group I and IV at day 84. X-ray analysis and histology both demonstrated clear signs of osteomyelitis after twelve weeks. Survival, clinical observations and weight assessment confirmed the ethical justifiable stress of the animals during the experiment., Conclusion: The presented small animal model of a two-stage revision in implant-related infection is a promising preclinical set-up for assessment of new treatment strategies of implant-related infections. Both high survival as well as reinfection rates were possible by simulating the clinical gold standard of two-stage revision surgery in an MRSA implant-related infection model. Therefore, the model can be deemed suitable for further preclinical in vivo testing., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The diagnosis of periprosthetic joint infection (PJI) remains a challenge. However, recent studies showed that synovial fluid biomarkers have demonstrated greater diagnostic accuracy than the currently used PJI diagnostic tests. In many diagnostic tests, combining several biomarkers into panels is critical for improving diagnostic efficiency, enhancing the diagnostic precision for specific diseases, and reducing cost. In this study, we prove that combining alpha-defensin and C-reactive protein (CRP) as biomarkers possesses the potential to provide accurate PJI diagnosis. To further verify the result, we developed a multi-target lateral flow immunoassay strip (msLFIA) with staking pad design to obtain on-site rapid response for clinical diagnosis of PJI. A total of 10 synovial fluid samples were tested using the msLFIA, and the results showed that the combined measurements of synovial fluid alpha-defensin and CRP levels were consistent with those obtained from a commercial enzyme-linked immunosorbent assay kit. In addition, we developed a multi-target lateral flow immunoassay strip (msLFIA) with staking pad design to obtain on-site rapid response for clinical diagnosis of PJI, which the multi-target design is used to increase specificity and the stacking pad design is to enhance detection sensitivity. As a result, the turnaround time of the highly sensitive test can be limited from several hours to 20 min. We expect that the developed msLFIA possesses the potential for routine monitoring of PJI as a convenient, low-cost, rapid and easy to use detection device for PJI.

Tissues from a periprosthetic joint infection (PJI) of the knee contain a heavy neutrophil polymorph (NP) infiltrate (> 5 NPs per high-powered field [HPF] by Musculoskeletal Infection Society [MSIS] criteria). PJI of the knee can be treated by a two-stage procedure and our aim was to determine whether the MSIS histological criteria for PJI diagnosis are valid in a second-stage revision knee arthroplasty. Periprosthetic tissues from 45 second-stage revision knee cases were analyzed histologically by hematoxylin-eosin and chloroacetate esterase (CAE) staining for the identification of NPs. The number of NPs was determined semiquantitatively and results correlated with the microbiological and clinical findings. In 9 of the 45 cases, an organism was cultured in two or more samples, meeting MSIS microbiological criteria for a definite diagnosis of PJI; histologically, seven of these cases contained > 5 per NPs per HPF on average, with the remaining two cases containing 1 NP and 2 NPs per HPF. In noninfected second-stage revisions, NPs were not seen in 30 cases with 6 cases showing less than 1 NP per HPF on average. The sensitivity, specificity, accuracy, and positive and negative predictive values of MSIS histological criteria (> 5 NPs per HPF) to diagnose PJI were 78%, 100%, 96%, 100%, and 95%, respectively. MSIS histological criteria for the diagnosis of PJI are valid for most but not all infected second-stage revision knee arthroplasties. Correlation of histology with clinical, microbiology and other laboratory findings is required to establish a diagnosis of PJI in second-stage revision knee arthroplasties., Competing Interests: The author has provided expert opinion in arthroplasty related medicolegal cases., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Purpose: To analyze the utility of arthroscopic biopsies for detection of periprosthetic infection in painful shoulder arthroplasty without objective signs of infection., Methods: A retrospective analysis of all patients who underwent a diagnostic arthroscopy for painful shoulder arthroplasty from June 2012 through July 2018 was performed. Patients with a subsequent revision shoulder arthroplasty after diagnostic arthroscopy were included. Arthroscopic tissue culture results were compared with the culture results of intraoperative tissue samples obtained at the time of open revision surgery. A minimum of 3 tissue samples from synovia and bone-prosthesis interface with signs of synovitis or abnormal appearance was routinely collected. Cases with 2 or more positive cultures for the same microorganism obtained at open revision surgery were considered as true presence of infection. The study protocol was reviewed and approved by the institutional ethics committee., Results: Twenty-three cases in 22 patients were included in this study. Five of these 23 cases were classified as true infection based on the samples obtained during open revision surgery, and 16 cases had a positive culture in diagnostic arthroscopy. Cutibacterium acnes was isolated in each case. Classifying any microbiologic growth in the arthroscopic biopsies as positive resulted in a sensitivity and negative predictive value of 100%, specificity of 39%, and positive predictive value of 31.3% for the detection of a periprosthetic shoulder infection (PPSI). If at least 2 positive samples with the same microbiologic growth in the arthroscopic biopsies were considered as positive, sensitivity and negative predictive value dropped to 80% and 94.4%, respectively, but the specificity and positive predictive value increased to 94.4% and 80%, respectively., Conclusions: Diagnostic arthroscopy is a useful diagnostic tool in patients with suspicion but no clear evidence of PPSI. Arthroscopically obtained tissue biopsies for culture offer a high sensitivity and specificity in the diagnosis of PPSI if at least 2 cultures positive for the same microorganism are considered as infection., Level of Evidence: Level III., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Introduction: Medical management of prosthetic joint infections (PJIs) relies on the identification of causative organisms through traditional culture-based approaches to guide therapy. However, diagnosis of many PJIs remains challenging, with many clinically apparent infections remaining culture-negative. Molecular diagnostics have the potential to increase diagnostic yield, particularly among culture-negative PJIs., Methods: Bone, tissue, or synovial fluid from patients with clinically identified PJIs were collected for inclusion in this study. Samples were assessed with traditional cultures and classified as culture-positive or -negative after 48 h. Samples subsequently underwent a Staphylococcus aureus -/ Kingella kingae -specific PCR followed by a 16s rRNA gene PCR., Results: A total of 77 unique patients with clinically identified PJIs contributed a total of 89 samples for inclusion in the study. There were 54 culture-negative and 35 culture-positive samples evaluated. The sensitivity and specificity of S. aureus PCR in culture-positive samples was 57.1% (95% CI, 34.1%-78.1%) and 92.9% (95% CI, 66.1%-98.9%), respectively. Among culture-positive samples, 16s rRNA gene PCR correctly identified 3 of 21 (14.3%) samples with S. aureus and 2 of 5 (40%) samples with Streptococcus spp. All molecular tests were negative in those with clinically identified, culture-negative PJI., Conclusions: Our study suggests that these diagnostic tools have a limited role in PJI diagnosis., (© 2018 American Association for Clinical Chemistry.)

Background: Implant-related spinal infections are a surgical complication associated with high morbidity. Due to infection, hardware removal may be necessary, which could lead to pseudarthrosis and the loss of stability and alignment., Objectives: To evaluate the accuracy and diagnostic value of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) in the workup of patients with suspected implant-related infections of the spine and to assess the clinical impact of PET/CT results on the management of these infections., Methods: The study included nine consecutive patients with a history of spinal surgery who underwent PET/CT for evaluation of suspected spinal implant related infection. All imaging studies were performed between January 2011 and December 2013. All 18F-FDG PET/CT scans were performed on an 8 slice PET/CT following an 18F-FDG injection. Images were scored both visually and semi-quantitatively by a radiology expert. Results were compared to additional imaging studies when available, which were correlated to clinical and bacteriological findings allowing calculation of sensitivity, specificity and accuracy., Results: Among the patients, five experienced hardware-related spinal infection. 18F-FDG PET/CT sensitivity was 80%, specificity 100%, and accuracy 88.9%. One scan produced a false negative; however, a second PET/CT scan revealed an infection., Conclusions: PET/CT was found to be valuable for the diagnosis of postoperative hardware-related spinal infection, especially when other imaging modalities were uninformative or inconclusive. As such, PET/CT could be useful for management of infection treatment.

Prosthetic joint infection (PJI) is a well-known and persisting problem. Active release coatings have promise to provide early protection to an implant by eradicating small colony biofilm contaminants or planktonic bacteria that can form biofilm. Traditional antibiotics can be limited as active release agents in that they have limited effect against biofilms and develop resistance at sub-lethal concentrations. A unique first-in-class compound (CZ-01127) was assessed as the active release agent in a silicone (Si)-based coating to prevent PJI in a sheep model of joint space infection. Titanium (Ti) plugs contained a porous coated Ti (PCTi) region and polymer-coated region. Plugs were implanted into a femoral condyle of sheep to assess the effect of the Si polymer on cancellous bone ingrowth, the effect of CZ-01127 on bone ingrowth, and the ability of CZ-01127 to prevent PJI. Microbiological results showed that CZ-01127 was able to eradicate bacteria in the local region of the implanted plugs. Data further showed that Si did not adversely affect bone ingrowth. However, bacteria that reached the joint space (synovium) were not fully eradicated. Outcomes suggested that the CZ-01127 coating provided local protection to the implant system in a challenging model, the design of which could be beneficial for testing future antimicrobial therapies for PJI. STATEMENT OF SIGNIFICANCE: Periprosthetic joint infection (PJI) is now commonplace, and constitutes an underlying problem that patients and physicians face. Active release antibiotic coatings have potential to prevent these infections. Traditional antibiotics are limited in their ability to eradicate bacteria that reside in biofilms, and are more susceptible to resistance development. This study addressed these limitations by testing the efficacy of a unique antimicrobial compound in a coating that was tested in a challenging sheep model of PJI. The unique coating was able to eradicate bacteria and prevent infection in the environment adjacent to the implant. Bacteria that escaped into the joint space still caused infection, yet benchmark data can be used to optimize the coating and translate it toward clinical use., (Published by Elsevier Ltd.)

Background: Blood culture bottles (BCBs) provide a semiautomated method for culturing periprosthetic tissue specimens. A study evaluating BCBs for culturing clinical samples other than body fluids is needed before implementation into clinical practice. Our objective was to evaluate use of the BacT/Alert® Virtuo blood culture system for culturing periprosthetic tissue specimens., Methods: The study was performed through the analysis of spiked (n = 36) and clinical (n = 158) periprosthetic tissue samples. Clinical samples were analyzed by the BCB method and the results were compared to the conventional microbiological culture-based method for time to detection and microorganisms identified., Results: The BacT/Alert® Virtuo blood culture system detected relevant bacteria for prosthetic joint infection in both spiked and clinical samples. The BCB method was found to be as sensitive (79%) as the conventional method (76%) (p = 0.844) during the analyses of clinical samples. The BCB method yielded positive results much faster than the conventional method: 89% against 27% detection within 24 h, respectively. The median detection time was 11.1 h for the BCB method (12 h and 11 h for the aerobic and the anaerobic BCBs, correspondingly)., Conclusion: We recommend using the BacT/Alert® Virtuo blood culture system for analyzing prosthetic joint tissue, since this detect efficiently and more rapidly a wider range of bacteria than the conventional microbiological method.

Purpose: The optimal timing of reimplantation of two-stage exchange arthroplasty for periprosthetic joint infection remains unknown. The purpose of the study was to (1) evaluate performance of combination of serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and frozen section in predicting persistent infection at the time of second-stage hip reimplantation and (2) compare accuracies of 5 and 10 polymorphonuclear neutrophils (PMNs) per high power field (HPF) as the threshold of frozen section., Methods: We retrospectively reviewed 97 two-stage exchange hip arthroplasties from 2012-2016. Persistent infection at time of reimplantation was diagnosed using the Musculoskeletal Infection Society (MSIS) criteria. Two diagnostic models were developed. Model 1 utilized ESR, CRP, and > 5 PMNs/HPF on frozen section. Model 2 utilized ESR, CRP, and > 10 PMNs/HPF. Receiver operating characteristic (ROC) curves of the two models were generated, and areas under the curves (AUCs) were compared. A set of sensitivity analysis, using the Delphi-based consensus criteria for treatment success, was conducted to verify the accuracy of our models., Results: The overall rate of infection at reimplantation was 14.4%. AUCs for models 1 and 2 were 0.709 (95% confidence interval [CI], 0.557-0.852) and 0.697 (95% CI, 0.529-0.847), respectively. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 57.1%, 88.0%, 44.4%, and 92.4%, respectively, in model 1 and 42.9%, 96.4%, 66.7%, and 90.9%, respectively, in model 2. Models 1 and 2 had no significant difference in predictive values (p = 0.821). Results remained robust in the sensitivity analysis., Conclusions: This study reveals that the combination of serum ESR, CRP, and frozen section has limited diagnostic value in predicting persistent infection at reimplantation. Additionally, no significant difference in accuracies between 5 and 10 PMNs/HPF as the threshold of frozen section were found. There is a need for timely biomarkers with higher accuracy in diagnosing infection before reimplantation.

Introduction: Prosthetic joint infections are an increasingly important problem among patients undergoing arthroplasty procedures, and are associated with significant morbidity, reduced quality of life, substantial healthcare costs, and even mortality. Arthroplasties are performed with increasing frequency in elderly patients, who present specific problems., Areas Covered: Surgical therapy is clearly influenced by the clinical status of the patient, which in some case can contraindicate surgery. Antibiotic selection is also affected by comorbidities and underlying diseases, which in some cases reduce therapeutic options. The authors review this together with the changes in pharmacokinetics and pharmacodynamics in the elderly population and the prospects for future research on prevention and treatment., Expert Opinion: The management of PJI in the elderly makes multidisciplinary teams even more mandatory than in other patients, because the complexity of these patients. A frequent scenario is that in which surgery is contraindicated with long-term suppressive treatment as the only available option. Treating physicians must consider the presence of multiple comorbidities, interactions with other treatments and secondary effects when choosing antibiotic treatment. An in-depth knowledge of the alterations in pharmacokinetics and pharmacodynamics in elderly patients is key for a proper treatment selection.

Background: Overall, fungi are estimated to cause approximately 1% of prosthetic joint infections, Candida glabrata account for less than 10% of these cases. No well-defined treatment strategy is available., Case Presentation: A 71-year-old Caucasian man with non-insulin-dependent diabetes was admitted for hip prosthesis revision. For the past 17 years he suffered from recurrent infection of a perianal fistula, the last episode being 1 week before admission, and was prescribed amoxicillin/clavulanate 1 g twice a day. At surgery, the synovial fluid tested positive for infection with the Synovasure® Alpha Defensin Test, and the orthopedic surgeon reported intraoperative evidence of infection. While the synovial fluid failed to grow microorganisms, seven different samples including periprosthetic tissue and the prosthesis grew Candida glabrata. Imipenem 2 g and teicoplanin 600 mg daily were administered during surgery. Also an antibiotic loaded spacer was positioned. A week later micafungin 100 mg a day was added, and after another week imipenem was replaced with ertapenem 1 g once a day. The combination of antibiotics and antifungal was administered for a total of 7 weeks, while he also underwent treatment of the perianal fistula. The reimplantation was performed after an 8-week antibiotic-free interval. Before reimplantation, his erythrocyte sedimentation rate and C-reactive protein level were normal. At reimplant surgery, several samples were collected for microbiology, before administering ertapenem 1 g, teicoplanin 600 mg and micafungin 100 mg once a day. This antimicrobial combination was continued for 15 days until the microbiologic investigations, including culture and molecular testing after sonication technique of the spacer, were reported negative for bacteria and fungi. In this patient, systemic antifungal and extensive debridement allowed for clinical and microbiologic cure., Conclusions: Although Candida glabrata prosthetic joint infection is a rare event, the incidence could increase in the future, and there is need for more definitive treatment protocols. Diagnosis depends on culture. Fungal etiology must always be included in the differential diagnosis of prosthetic joint infection.

Introduction: The Musculoskeletal Infection Society (MSIS) has defined specific clinical and laboratory criteria for the diagnosis of periprosthetic joint infection (PJI). In this study we assessed the diagnostic utility of MSIS microbiological and histological criteria for PJI in 138 cases of septic and aseptic knee implant failure., Materials and Methods: Intra-operative samples from 60 cases of knee septic implant failure (SIF) and 78 cases of aseptic implant failure (AIF), defined on the basis of clinical, laboratory and operative findings/surgical management, were analysed microbiologically and histologically. Findings were correlated with the final clinical diagnosis and the specificity, sensitivity, accuracy, positive and negative predictive value of MSIS microbiological and histological criteria for knee PJI were assessed., Results: 80% of SIF cases showed culture of the same organism from two or more samples (ie MSIS microbiological criteria for definite PJI); 8.3% grew an organism from one sample, and 11.7% showed no growth from any sample. 23.1% of AIF cases grew an organism from one sample and 76.9% showed no growth from any sample. MSIS histological criteria for PJI identified 96.7% of SIF cases. The sensitivity, specificity, accuracy and positive and negative predictive value of MSIS histological criteria for PJI were 96.7%, 100%, 98.6%, 100% and 97.5%, respectively. MSIS microbiological and histological criteria identified all AIF cases., Conclusions: Knee PJI is more often identified by current MSIS histological than microbiological criteria. A significant proportion of SIF cases show either no growth or growth of an organism from only one sample. AIF is identified by both MSIS microbiological and histological criteria. Correlation of clinical, radiological and laboratory findings is required for the diagnosis of knee PJI.

Background: Titanium (Ti) implant-associated infection, which is mostly caused by bacterial adhesion and biofilm formation, may result in implant failure and secondary surgery. Thus it is an urgent issue to prevent bacterial infections at the earliest step. Purpose: To develop a novel surface strategy of polydopamine (PDA) and silver (Ag) nanoparticle-loaded TiO 2 nanorods (NRDs) coatings on Ti alloy. Materials and methods: Ag-TiO 2 @PDA NRDs was fabricated on Ti alloy by hydrothermal synthesis. The antibacterial activity of Ag-TiO 2 @PDA NRDs against Escherichia coli and methicillin-resistant Staphylococcus aureus were tested by FE-SEM, Live/Dead staining, zone of inhibition, bacteria counting method and protein leakage analysis in vitro . In addition, an implant infection model was conducted and the samples were tested by X-ray, Micro-CT and histological analysis in vivo . Besides, cell morphology and cytotoxicity of Mouse calvarial cells (MC3T3-E1) were characterized by FE-SEM, immunofluorescence and CCK-8 test in vitro . Results: Our study successfully developed a new surface coating of Ag-TiO 2 @PDA NRDs. The selective physical puncture of bacteria and controlled release of Ag+ ions of Ag-TiO 2 @PDA NRDs achieved a long-lasting bactericidal ability and anti-biofilm activity with satisfied biocompatibility. Conclusion: This strategy may be promising for clinical applications to reduce the occurrence of infection in the implant surgeries., Competing Interests: There are no potential conflicts of interest for the authors to disclose in this work.

Background: Obese patients are more likely to develop periprosthetic joint infection (PJI) after primary total joint arthroplasty. This study compared the clinical and microbiological characteristics of non-obese, obese and severely obese patients with early PJI, in order to ultimately optimize antibiotic prophylaxis and other prevention measures for this specific patient category., Methods: We retrospectively evaluated patients with early PJI of the hip and knee treated with debridement, antibiotics and implant retention (DAIR) between 2006 and 2016 in three Dutch hospitals. Only patients with primary arthroplasties indicated for osteoarthritis were included. Early PJI was defined as an infection that developed within 90 days after index surgery. Obesity was defined as a BMI ≥30kg/m2 and severe obesity as a BMI ≥35kg/m2., Results: A total of 237 patients were analyzed, including 64 obese patients (27.0%) and 62 severely obese patients (26.2%). Compared with non-obese patients, obese patients had higher rates of polymicrobial infections (60.3% vs 33.3%, p<0.001) with more often involvement of Enterococcus species (27.0% vs 11.7%, p = 0.003). Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (12.9% vs 2.3%, p = 0.001). These results were only found in periprosthetic hip infections, comprising Gram-negative PJIs in 34.2% of severely obese patients compared with 24.7% in obese patients and 12.7% in non-obese patients (p = 0.018)., Conclusions: Our results demonstrate that obese patients with early periprosthetic hip infections have higher rates of polymicrobial infections with enterococci and Gram-negative rods, which stresses the importance of improving preventive strategies in this specific patient category, by adjusting antibiotic prophylaxis regimens, improving disinfection strategies and optimizing postoperative wound care., Competing Interests: The authors have declared that no competing interests exist.

We report on the first case of a periprosthetic joint infection with the anaerobic Gram-positive rod Slackia exigua as the causative agent. The bacterium is part of human oral microbiota and has so far mainly been associated with periodontal diseases., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Late complications in ascending aortic surgeries are uncommon and may occur by infectious processes, usually caused by gram positive bacteria. We report a case of aortic prosthesis infection by Porphyromonas pogonae, an anaerobic gram-negative coccobacillus that can grow under microaerobic conditions, three years after ascending aortic reconstruction surgery., (Copyright © 2019. Published by Elsevier Ltd.)

Despite low sensitivity, culture of periprosthetic tissue (PPT) specimens on agars and in broths has traditionally been used for the detection of causative microorganisms in patients suspected for prosthetic joint infection (PJI). The aim of this study was to evaluate the added diagnostic value of culturing PPT in blood culture bottles (BCB) over the conventional combination of standard agar and broth alone. This prospective cohort study was conducted over a 12-month period and included consecutive patients undergoing revision arthroplasty. Overall, 113 episodes from 90 subjects were studied; 45 subjects (50.0%) met the Infectious Diseases Society of America (IDSA) criteria for PJI, of whom the majority (75.6%) had an acute infection. Sensitivity and specificity of culture were assessed using IDSA criteria for PJI as gold standard. Although the increase in sensitivity from 84.44 (CI 70.54; 93.51) to 93.33% (81.73; 98.60) was not significant, added diagnostic value of culturing PPT in BCBs was demonstrated by the significantly higher number of detected pathogens in culture sets with BCBs compared to culture without BCBs (61 pathogens in conventional set versus 89 when BCBs were included for 57 PJI episodes, P = <0.0001). In 17 (29.8%) episodes, microorganisms were cultured from BCBs only, and in 9 (52.9%) of these episodes, virulent pathogens were found. This study demonstrates that PPT culture in BCBs leads to isolation of additional microorganisms, both virulent and low-virulent, which were not cultured with use of agars and broths alone. Isolation of additional causative microorganisms has serious consequences for the treatment strategy in PJI.

The purpose of this study was to evaluate the efficacy of echinocandins in the treatment of Candida prosthetic joint infection (PJI) based on published literature and on patients we examined. A structured literature review of multiple databases was conducted to identify patients who received echinocandins for Candida PJIs. Additionally, we describe here the first cases of PJIs due to C. parapsilosis, successfully treated with prolonged anidulafungin therapy. Out of 17 patients, 12 were female and the mean age at diagnosis was 66.0 years. No risk factors associated with Candida PJIs were found in four patients (23.5%). Infection sites included the knee (n = 10, 62.5%), the hip (n = 6, 35.3%) and the shoulder (n = 1, 5.9%). The most frequently isolated Candida species were C. albicans (n = 7, 41.2%) and C. glabrata (n = 7, 41.2%), followed by C. parapsilosis (n = 2, 11.8%) and C. freyschussii (n = 1, 5.9%). All patients were cured with the combination of systemic antifungal therapy and surgical interventions. Two-stage exchange arthroplasty and resection arthroplasty were performed in five and nine patients, respectively. The most frequently used echinocandins were caspofungin (n = 11, 64.7%), followed by anidulafungin (n = 4, 23.5%) and micafungin (n = 2, 11.8%). The median duration (days) of echinocandin therapy was as follows: caspofungin (25.5, range 8-56), micafungin (14.0, range 4-56) and anidulafungin (58, range 14-90). This study supports the effective role of echinocandins, as well as the potential advantage of surgical intervention in the treatment of Candida PJIs. Furthermore, it provides fundamental data on the safety of long-term echinocandin therapy.