Bionic Nanocoating of Prosthetic Grafts Significantly Reduces Bacterial Growth

Prosthetic materials are a source of bacterial infections, with significant morbidity and mortality. Utilizing the bionic "Lotus effect," we generated superhydrophobic vascular prostheses by nanocoating and investigated their resistance to bacterial colonization. Nanoparticles were generated from silicon dioxide (SiO2), and coated vascular prostheses developed a nanoscale roughness with superhydrophobic characteristics. Coated grafts and untreated controls were incubated with different bacterial solutions including heparinized blood under mechanical stress and during artificial perfusion and were analyzed. Bioviability- and toxicity analyses of SiO2 nanoparticles were performed. Diameters of SiO2 nanoparticles ranged between 20 and 180 nm. Coated prostheses showed a water contact angle of > 150° (mean 154 ± 3°) and a mean water roll-off angle of 9° ± 2°. Toxicity and viability experiments demonstrated no toxic effects of SiO2 nanoparticles on human induced pluripotent stem cell-derived cardiomyocytes endothelial cells, fibroblasts, and HEK239T cells. After artificial perfusion with a bacterial solution (Luciferase+ Escherichia coli), bioluminescence imaging measurements showed a significant reduction of bacterial colonization of superhydrophobic material-coated prostheses compared to that of untreated controls. At the final measurement (t = 60 min), a 97% reduction of bacterial colonization was observed with superhydrophobic material-coated prostheses. Superhydrophobic vascular prostheses tremendously reduced bacterial growth. During artificial perfusion, the protective superhydrophobic effects of the vascular grafts could be confirmed using bioluminescence imaging.

Rat model of recalcitrant prosthetic joint infection using biofilm inocula

Prosthetic joint infection (PJI) is a rare but devastating complication of joint arthroplasty. Biofilm formation around the prosthesis confers tolerance to antibiotics so that treatment is challenging. Most animal models of PJI use planktonic bacteria to establish the infection which fails to reproduce the pathology of chronic infection. We aimed to establish a rat model of Staphylococcus aureus PJI in male Sprague-Dawley rats using biofilm inocula and demonstrate its tolerance to frontline antibiotics. Pilot studies indicated that infection could be introduced to the knee joint by a biofilm-coated pin but that handling the prosthetic without disturbing the biofilm was difficult. We, therefore, developed a pin with a slotted end and used a miniature-biofilm reactor to develop mature biofilm in this niche. These biofilm-laden pins consistently produced infection of the bone and joint space. Treatment with high dose cefazolin, 250 mg/kg, starting the day of surgery reduced or cleared pin-adherent bioburden within 7 days, however when escalation from 25 to 250 mg/kg cefazolin treatment was delayed for 48 h, rats were unable to clear the infection. To track infections, we used bioluminescent bacteria, however, the bioluminescent signal did not accurately track the degree of infection in the bone and joint space as the signal did not penetrate the bone. In conclusion, we demonstrate that using a custom prosthetic pin, we can generate biofilm in a specific niche using a novel bioreactor setup and initiate a rat PJI that rapidly develops tolerance to supra-clinical doses of cefazolin.

Development of evidence-based guidelines for the treatment and management of periprosthetic hip infection

Aims

Periprosthetic hip-joint infection is a multifaceted and highly detrimental outcome for patients and clinicians. The incidence of prosthetic joint infection reported within two years of primary hip arthroplasty ranges from 0.8% to 2.1%. Costs of treatment are over five-times greater in people with periprosthetic hip joint infection than in those with no infection. Currently, there are no national evidence-based guidelines for treatment and management of this condition to guide clinical practice or to inform clinical study design. The aim of this study is to develop guidelines based on evidence from the six-year INFection and ORthopaedic Management (INFORM) research programme.

Methods

We used a consensus process consisting of an evidence review to generate items for the guidelines and online consensus questionnaire and virtual face-to-face consensus meeting to draft the guidelines.

Results

The consensus panel comprised 21 clinical experts in orthopaedics, primary care, rehabilitation, and healthcare commissioning. The final output from the consensus process was a 14-item guideline. The guidelines make recommendations regarding increased vigilance and monitoring of those at increased risk of infection; diagnosis including strategies to ensure the early recognition of prosthetic infection and referral to orthopaedic teams; treatment, including early use of DAIR and revision strategies; and postoperative management including appropriate physical and psychological support and antibiotic strategies.

Conclusion

We believe the implementation of the INFORM guidelines will inform treatment protocols and clinical pathways to improve the treatment and management of periprosthetic hip infection.

Cite this article: Bone Jt Open 2023;4(4):226–233.

Low Morbidity Anatomical Revascularisation for an Infected Aorto-Bifemoral Graft Using a Staged Hybrid Procedure

A 66-year-old woman presented with a right femoral false aneurysm following an aortobifemoral bypass for lifestyle-limiting claudication. A computed tomography (CT) angiogram revealed features of complete aortobifemoral graft infection. A two-stage procedure was performed. The first hybrid stage involved the excision of only the femoral components and covered stenting of the aortic stump, along with recanalization of bilateral native iliac systems. The second stage, six weeks later, involved aortic stent and graft explant via midline laparotomy with aortic bovine pericardium patch repair (LeMaitre Vascular Inc, Burlington, Massachusetts). Follow-up imaging demonstrated no residual infection, and the patient remained without complication at the 12-month follow-up. This novel approach utilizes hybrid surgical techniques and modern bioprosthetic material to safely manage an infected aortobifemoral bypass graft.

Orthopedic infections due to Trichosporon species: Case series and literature review

Reports of orthopedic fungal infections caused by Trichosporon species are extremely scarce, thus we aimed to describe a case series and review the cases published in the literature. Patients were retrospectively included if a previous culture of bone, joint, or soft tissues had resulted positive for Trichosporon species along with a clinical diagnosis of an orthopedic infection. Eight patients were included with diverse orthopedic conditions, most of them cases of osteomyelitis. The main isolated species was Trichosporon asahii. All patients were treated with antifungals, mainly voriconazole, and surgical management, resulting in high rates of clinical improvement and low associated mortality.

Prosthetic joint infection by Bordetella holmesii: Case report and a review of the literature

INTRODUCTION

Bordetella holmesii is a Gram-negative coccobacillus involved in different infections mostly described in case reports. Prosthetic joint infections in relation to this pathogen are rare. Here, we present the third case of B. holmesii in a patient without anatomical or functional spleen dysfunction.

CASE REPORT

The patient was a 62-year-old female with a total knee prosthesis implanted in 1997 that required multiple replacements of the femoral component due to aseptic loosening in the past years. The patient was admitted to our hospital for an elective replacement surgery due to new radiological signs of loosening. B. holmesii was isolated from synovial fluid obtained during surgery. The identification was performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and confirmed by 16S rRNA gene amplification and sequencing. Antibiotic treatment was started but 14 days after surgery the patient presented pain and joint effusion. An arthrocentesis was performed and synovial fluid culture was positive again for B. holmesii. Surgical debridement including polyethylene replacement was performed and antibiotic treatment was continued for 3 months. After a 2-year follow-up period, the patient remained asymptomatic and physical examination showed normal function of the prosthesis.

CONCLUSION

B. holmesii is an uncommon cause of bone and joint infections. This case indicates that this microorganism is a potential pathogen of prosthetic or native arthritis, and it should be considered when cultures are negative and in cases presenting torpid evolution.

A single-center experience in the eversion femoral endarterectomy

OBJECTIVES

Endarterectomy is the treatment of choice for arterial occlusive disease of the femoral bifurcation. Longitudinal arteriotomy and prosthetic patch angioplasty is the standard technique but, due to the increasing concerns with prosthetic-related infections and multidrug-resistant pathogens our group adopted an alternative approach. We present our experience with eversion femoral endarterectomy.

METHODS

All patients submitted to eversion femoral endarterectomy in a single institution during 2016-2019 were retrospectively analyzed. Patient demographics, surgical data, and complications were captured from medical records.

RESULTS

Nineteen patients, 84.2% male and a median age of 67 years (IQR 62-78) were submitted to eversion femoral endarterectomy with a median follow-up of 180 days (IQR 71-395). Seventeen (89.4%) patients were treated for chronic limb ischemia and the other two were submitted to femoral endarterectomy during endovascular aortic aneurysm repair. Most of the patients had smoking history (84.2%), followed by hypertension (68.4%), dyslipidemia (63.2%), coronary heart disease (29.4%), and diabetes (26.3%). Only 3 patients (15.8%) were submitted exclusively to endarterectomy, 13 (68.4%) were submitted to endarterectomy as an adjuvant for peripheral endovascular treatment, 2 (10.5%) as a concomitant procedure to endovascular repair of aortic aneurysm, and 1 (5.3%) was complemented with thrombectomy of the femoro-popliteal sector. Primary patency rates were 100% and 87.5% (CI (38.7-98.1)) at 6 and 12 months, respectively. Primary-assisted and secondary patency rates were 100%. The 30-day mortality rate was 5.3% (n = 1) and complication rate 10.5% (n = 2). One patient complicated with acute renal disease related to rhabdomyolysis. Another patient developed a wound-related hematoma treated with surgical drainage, but died three days after consequent to ischemia-reperfusion injury.

CONCLUSIONS

Eversion femoral endarterectomy is a safe and feasible technique, with good patency results and respecting the concept of leaving nothing behind. A careful control of the proximal and distal endpoints is essential for the success of the technique.

Cutibacterium acnes Isolates from Deep Tissue Specimens Retrieved during Revision Shoulder Arthroplasty: Similar Colony Morphology Does Not Indicate Clonality

Cutibacterium acnes is the most common bacterium associated with periprosthetic shoulder infections. Sequencing of C. acnes has been proposed as a potential rapid diagnostic tool and a method of determining subtypes associated with pathogenicity and antibiotic resistance patterns. When multiple deep samples from the same surgery are culture positive for the same species and the isolates show the same culture phenotype, it is typically assumed that these isolates are clonal. However, it is well-known that C. acnes is not clonal on the skin of most individuals. We hypothesized that the C. acnes bacteria recovered at the time of revision shoulder arthroplasty would often represent more than one subtype, and we tested this hypothesis in this work. For patients undergoing revision shoulder arthroplasty, multiple samples from the surgical field were taken. For those patients with multiple samples that were culture positive for C. acnes, isolates from each sample were subjected to full genome sequencing. Of 11 patients, 5 (45%) had different subtypes of C. acnes within the deep tissues even though the colony morphology was similar. One patient had four subtypes in the deep tissues, while four patients had two different subtypes. Up to four different subtypes of C. acnes were observed in the deep tissues of a single patient. Clonality of C. acnes isolates from deep specimens from a potential periprosthetic shoulder infection cannot be assumed. Sequence-based characterization of virulence and antibiotic resistance may require testing of multiple deep specimens.

Clinical Presentation, Management, and Prognosis of Pseudogout in Joint Arthroplasty: A Retrospective Cohort Study

Introduction: Calcium pyrophosphate deposition disease (CPPD), or pseudogout, is rare in prosthetic joints, but can mimic prosthetic joint infection (PJI) according to case reports. The purpose of this case series is to describe the demographics, presentation, management, and outcomes of a cohort of these patients seen at our academic medical center. Methods: Patients with post-implant pseudogout, who were evaluated at our medical center between January 1, 2000 and June 30, 2016, were identified from our EHR. Data pertaining to demographics, presentation, management, and outcomes were abstracted, and patients were categorized into two groups based on presence of concomitant infection along with positive CPDD findings in synovial fluid. Results: 22 patients were included. 90.9% of cases involved a TKA. The most common indication for arthroplasty was degenerative joint disease. Only four patients had a history of previous gout or pseudogout, three of which belonged to the group with no evidence of concomitant joint infection. Clinical features for patients without concomitant infection included pain (100%), swelling at the joint (88.9%), redness (33.3%), fever (22.2%), and decreased range of motion (100%). 45.5% of patients received antibiotics prior to joint aspiration (44.4% of patients with negative synovial fluid cultures, 46.2% of patients with concomitant infection). Conclusion: Our study suggests similar clinical presentation between post-implant pseudogout and PJI. Among patients with pseudogout as well as in those with PJI, the first dose of antibiotics should not be given before sampling for synovial culture. Unfortunately, many patients receive antibiotics prior to culture ascertainment, which raises concern for antibiotic overuse.

Efficacy of antibiotic treatment of implant-associated Staphylococcus aureus infections with moxifloxacin, flucloxacillin, rifampin, and combination therapy: an animal study

The efficacy of antibiotic monotherapy and combination therapy in the treatment of implant-associated infection by Staphylococcus aureus was evaluated in an animal study. The femoral medullary cavity of 66 male Wistar rats was contaminated with S. aureus (ATCC 29213) and a metal device was implanted, of which 61 could be evaluated. Six treatment groups were studied: flucloxacillin, flucloxacillin in combination with rifampin, moxifloxacin, moxifloxacin in combination with rifampin, rifampin, and a control group with aqua. The treatment was applied for 14 days. After euthanasia, the bacterial counts in the periprosthetic bone, the soft tissue, and the implant-associated biofilm were measured. Both antibiotic combination treatments (moxifloxacin plus rifampin and flucloxacillin plus rifampin) achieved a highly significant decrease in microbial counts in the bone and soft tissue and in the biofilm. Mono-antibiotic treatments with either moxifloxacin or flucloxacillin were unable to achieve a significant decrease in microbial counts in bone and soft tissue or the biofilm, whilst rifampin was able to reduce the counts significantly only in the biofilm. Antibiotic resistance was measured in 1/3 of the cases in the rifampin group, whereas no resistance was measured in all other groups. The results show that combinations of both moxifloxacin and flucloxacillin plus rifampin are adequate for the treatment of periprosthetic infections due to infections with S. aureus, whereas monotherapies are not effective or not applicable due to the rapid development of antibiotic resistance. Therefore, moxifloxacin is an effective alternative in combination with rifampin for the treatment of implant-associated infections.

Prevention of Propionibacterium acnes biofilm formation in prosthetic infections in vitro

BACKGROUND

The role of Propionibacterium acnes in shoulder arthroplasty and broadly in orthopedic prosthetic infections has historically been underestimated, with biofilm formation identified as a key virulence factor attributed to invasive isolates. With an often indolent clinical course, P acnes infection can be difficult to detect and treat. This study investigates absorbable cements loaded with a broad-spectrum antibiotic combination as an effective preventive strategy to combat P acnes biofilms.

METHODS

P acnes biofilm formation on an unloaded synthetic calcium sulfate (CaSO₄) bone void filler cement bead was evaluated by scanning electron microscopy over a period of 14 days. Beads loaded with tobramycin alone or vancomycin alone (as comparative controls) and beads loaded with a vancomycin-tobramycin dual treatment were assessed for their ability to eradicate planktonic P acnes, prevent biofilm formation, and eradicate preformed biofilms using a combination of viable-cell counts, confocal microscopy, and scanning electron microscopy.

RESULTS

P acnes surface colonization and biofilm formation on unloaded CaSO₄ beads was slow. Beads loaded with antibiotics were able to kill planktonic cultures of 10⁶ colony-forming units/mL, prevent bacterial colonization, and significantly reduce biofilm formation over periods of weeks. Complete eradication of established biofilms was achieved with a contact time of 1 week.

CONCLUSIONS

This study demonstrates that antibiotic-loaded CaSO₄ beads may represent an effective antibacterial and antibiofilm strategy to combat prosthetic infections in which P acnes is involved.

Engineered biomaterial and biophysical stimulation as combinatorial strategies to address prosthetic infection by pathogenic bacteria

A plethora of antimicrobial strategies are being developed to address prosthetic infection. The currently available methods for implant infection treatment include the use of antibiotics and revision surgery. Among the bacterial strains, Staphylococcus species pose significant challenges particularly, with regard to hospital acquired infections. In order to combat such life threatening infectious diseases, researchers have developed implantable biomaterials incorporating nanoparticles, antimicrobial reinforcements, surface coatings, slippery/non-adhesive and contact killing surfaces. This review discusses a few of the biomaterial and biophysical antimicrobial strategies, which are in the developmental stage and actively being pursued by several research groups. The clinical efficacy of biophysical stimulation methods such as ultrasound, electric and magnetic field treatments against prosthetic infection depends critically on the stimulation protocol and parameters of the treatment modality. A common thread among the three biophysical stimulation methods is the mechanism of bactericidal action, which is centered on biophysical rupture of bacterial membranes, the generation of reactive oxygen species (ROS) and bacterial membrane depolarization evoked by the interference of essential ion-transport. Although the extent of antimicrobial effect, normally achieved through biophysical stimulation protocol is insufficient to warrant therapeutic application, a combination of antibiotic/ROS inducing agents and biophysical stimulation methods can elicit a clinically relevant reduction in viable bacterial numbers. In this review, we present a detailed account of both the biomaterial and biophysical approaches for achieving maximum bacterial inactivation. Summarizing, the biophysical stimulation methods in a combinatorial manner with material based strategies can be a more potent solution to control bacterial infections. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2174-2190, 2017.

99m-Tc-ubiquicidin scintigraphy in diagnosis of knee prosthesis infection and comparison with F-18 fluorodeoxy-glucose positron emission tomography/computed tomography

Total knee arthroplasty has witnessed a significant increase in recent years. Despite the advantages of this surgical procedure, it has some complications, the most serious of which is prosthetic infection. The discrimination of bacterial infections from sterile inflammatory processes is of great importance in the management of periprosthetic infection (PPI). Ubiquicidin (UBI) is a synthetic antimicrobial peptide fragment reported to be highly infection-specific. Tc99m-UBI has recently been reported to be a promising radiotracer for infection imaging. We report a case of left knee PPI diagnosed using 99mTc-UBI scintigraphy and compared with F-18 fluorodeoxy-glucose positron emission tomography.

High-throughput assay for bacterial adhesion on acellular dermal matrices and synthetic surgical materials

BACKGROUND

There has been increasing use of synthetic and acellular dermal matrix materials in surgery, ranging from breast reconstruction to hernia repairs. There is a paucity of data on how acellular dermal matrix compares with other surgical materials as a substrate for bacterial adhesion, the first step in formation biofilm, which occurs in prosthetic wound infections. The authors have designed a high-throughput assay to evaluate Staphylococcus aureus adherence on various synthetic and biologically derived materials.

METHODS

Clinical isolates of S. aureus (strains SC-1 and UAMS-1) were cultured with different materials, and bacterial adherence was measured using a resazurin cell vitality assay. Four materials that are commonly used in surgery were evaluated: Prolene mesh, Vicryl mesh, and two different acellular dermal matrix preparations (AlloDerm and FlexHD). The authors were able to develop a high-throughput and reliable assay for quantifying bacterial adhesion on synthetic and biologically derived materials.

RESULTS

The resazurin vitality assay can be reliably used to quantify bacterial adherence to acellular dermal matrix material and synthetic material. S. aureus strains SC-1 and UAMS-1 both adhered better to acellular dermal matrix materials (AlloDerm versus FlexHD) than to the synthetic material Prolene. S. aureus also adhered better to Vicryl than to Prolene. Strain UAMS-1 adhered better to Vicryl and acellular dermal matrix materials than did strain SC-1.

CONCLUSIONS

The results show that S. aureus adheres more readily to acellular dermal matrix material than to synthetic material. The resazurin assay provides a standard method for evaluating surgical materials with regard to bacterial adherence and potential propensity for biofilm development.

The use of superparamagnetic nanoparticles for prosthetic biofilm prevention

As with all surgical procedures, implantation comes with the added risk of infection. The goal of this in vitro study was to explore the use of superparamagnetic iron oxide nanoparticles (SPION) as a multifunctional platform to prevent biofilm formation. Results showed for the first time decreased Staphylococcus epidermidis numbers when exposed to 100 microg/ml of SPION for 12 hours and this trend continued for up to 48 hours. Prevention of colony assembly, a prerequisite to biofilm formation, was also observed at lower SPION dosages of 10 microg/ml after 12 hours. Coupled with previous studies demonstrating enhanced bone cell functions in the presence of the same concentration of SPION, the present results provided much promise for the use of SPION for numerous anti-infection orthopedic applications.