2023 International Consensus Meeting on musculoskeletal infection: Summary from the treatment workgroup and consensus on treatment in preclinical models

In vitro and in vivo studies are critical for the preclinical efficacy assessment of novel therapies targeting musculoskeletal infections (MSKI). Many preclinical models have been developed and applied as a prelude to evaluating safety and efficacy in human clinical trials. In performing these studies, there is both a requirement for a robust assessment of efficacy, as well as a parallel responsibility to consider the burden on experimental animals used in such studies. Since MSKI is a broad term encompassing infections varying in pathogen, anatomical location, and implants used, there are also a wide range of animal models described modeling these disparate infections. Although some of these variations are required to adequately evaluate specific interventions, there would be enormous value in creating a unified and standardized criteria to animal testing in the treatment of MSKI. The Treatment Workgroup of the 2023 International Consensus Meeting on Musculoskeletal Infection was responsible for questions related to preclinical models for treatment of MSKI. The main objective was to review the literature related to priority questions and estimate consensus opinion after voting. This document presents that process and results for preclinical models related to (1) animal model considerations, (2) outcome measurements, and (3) imaging.

Sterility of Ethyl Chloride Spray After Use in the Clinic

Background: Ethyl chloride spray is used frequently in the outpatient setting as a local anesthetic for injections and aspirations with varying consensus about the sterility of the spray. We hypothesize that ethyl chloride spray remains sterile and would show no bacterial growth during routine clinical use. Methods: Thirteen ethyl chloride bottles were collected for testing. Two unopened bottles were used as controls. Eleven unopened bottles were placed in orthopedic clinics and recollected after varying duration of use. The final volume and duration of use were recorded. Each bottle was sprayed in a separate test tube and allowed to evaporate. Trypticase soy broth was added to each tube and incubated for 48 hours. Control test tubes with broth alone were prepared and incubated under the same conditions. Cultures were evaluated at 24 and 48 hours. Results: The mean duration of ethyl chloride bottle use prior to culturing was 26 days. The average volume used per day was 1.9 mL. Each ethyl chloride bottle had an initial volume of 103.5 mL. Using the average daily volume usage, an extrapolated lifespan of each bottle was estimated at 7.7 weeks. None of the samples showed bacterial or fungal growth at 24 or 48 hours. Conclusion: Ethyl chloride bottles used in the clinical settings showed no bacterial or fungal contamination through their shelf life and routine use. The duration and amount of use did not affect sterility. Although the antimicrobial activity of ethyl chloride spray on skin is debated, ethyl chloride itself remains sterile through clinical use.

Adjuvant antibiotic-loaded bone cement: Concerns with current use and research to make it work

Antibiotic-loaded bone cement (ALBC) is broadly used to treat orthopaedic infections based on the rationale that high-dose local delivery is essential to eradicate biofilm-associated bacteria. However, ALBC formulations are empirically based on drug susceptibility from routine laboratory testing, which is known to have limited clinical relevance for biofilms. There are also dosing concerns with nonstandardized, surgeon-directed, hand-mixed formulations, which have unknown release kinetics. On the basis of our knowledge of in vivo biofilms, pathogen virulence, safety issues with nonstandardized ALBC formulations, and questions about the cost-effectiveness of ALBC, there is a need to evaluate the evidence for this clinical practice. To this end, thought leaders in the field of musculoskeletal infection (MSKI) met on 1 August 2019 to review and debate published and anecdotal information, which highlighted four major concerns about current ALBC use: (a) substantial lack of level 1 evidence to demonstrate efficacy; (b) ALBC formulations become subtherapeutic following early release, which risks induction of antibiotic resistance, and exacerbated infection from microbial colonization of the carrier; (c) the absence of standardized formulation protocols, and Food and Drug Administration-approved high-dose ALBC products to use following resection in MSKI treatment; and (d) absence of a validated assay to determine the minimum biofilm eradication concentration to predict ALBC efficacy against patient specific micro-organisms. Here, we describe these concerns in detail, and propose areas in need of research.

Are Medical Grade Bioabsorbable Polymers a Viable Material for Fused Filament Fabrication?

Lumbar fusion surgery has grown in popularity as a solution to lower back pain. Surgical site infection (SSI) is a serious complication of spinal surgery, affecting as high as 8.5% of the patient population. If the SSI cannot be eradicated with intravenous antibiotics, the next step is second surgery, which increases the cost imposed on the patient and extends recovery time. An implantable ultrasound-triggered polyether ether ketone device for the dispersal of antibiotics has been developed as a potential solution. In this study, the device was constructed of bioabsorbable medical grade polymer, enabling gradual degradation, and manufactured via fused filament fabrication (FFF). A novel bioabsorbable filament was manufactured and validated with gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The filament was consistent in molecular weight and thermal properties (p = 0.348 and p = 0.487, respectively). The filament was utilized for FFF of the device. Dimensional accuracy of the device was assessed with μCT analysis. Dimensional differences between the printed device and intended design were minimal. Degradation of raw material, filament, and the device was performed in accordance to ASTM F1635-16 for a month to determine how melting the material impacted the degradation properties. The degradation rate was found to be similar among the samples weeks one through three however, the raw material degraded at a slower rate by the final week (p = 0.039). This study demonstrated the feasibility of utilizing medical grade bioabsorbable polymers in FFF.

2018 international consensus meeting on musculoskeletal infection: Summary from the biofilm workgroup and consensus on biofilm related musculoskeletal infections

Biofilm-associated implant-related bone and joint infections are clinically important due to the extensive morbidity, cost of care and socioeconomic burden that they cause. Research in the field of biofilms has expanded in the past two decades, however, there is still an immense knowledge gap related to many clinical challenges of these biofilm-associated infections. This subject was assigned to the Biofilm Workgroup during the second International Consensus Meeting on Musculoskeletal Infection held in Philadelphia USA (ICM 2018) (https://icmphilly.com). The main objective of the Biofilm Workgroup was to prepare a consensus document based on a review of the literature, prepared responses, discussion, and vote on thirteen biofilm related questions. The Workgroup commenced discussing and refining responses prepared before the meeting on day one using Delphi methodology, followed by a tally of responses using an anonymized voting system on the second day of ICM 2018. The Working group derived consensus on information about biofilms deemed relevant to clinical practice, pertaining to: (1) surface modifications to prevent/inhibit biofilm formation; (2) therapies to prevent and treat biofilm infections; (3) polymicrobial biofilms; (4) diagnostics to detect active and dormant biofilm in patients; (5) methods to establish minimal biofilm eradication concentration for biofilm bacteria; and (6) novel anti-infectives that are effective against biofilm bacteria. It was also noted that biomedical research funding agencies and the pharmaceutical industry should recognize these areas as priorities. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Cold Plasmas for Biofilm Control: Opportunities and Challenges

Bacterial biofilm infections account for a major proportion of chronic and medical device associated infections in humans, yet our ability to control them is compromised by their inherent tolerance to antimicrobial agents. Cold atmospheric plasma (CAP) represents a promising therapeutic option. CAP treatment of microbial biofilms represents the convergence of two complex phenomena: the production of a chemically diverse mixture of reactive species and intermediates, and their interaction with a heterogeneous 3D interface created by the biofilm extracellular polymeric matrix. Therefore, understanding these interactions and physiological responses to CAP exposure are central to effective management of infectious biofilms. We review the unique opportunities and challenges for translating CAP to the management of biofilms.

Covalent attachment of P15 peptide to titanium surfaces enhances cell attachment, spreading, and osteogenic gene expression

P15, a synthetic 15 amino acid peptide, mimics the cell-binding domain within the alpha-1 chain of human collagen is being tested in clinical trials to determine if it enhances bone formation in spinal fusions. We hypothesize that covalent attachment of P15 to titanium implants may also serve to promote osseointegration. To test this hypothesis, we measured osteoblast and mesenchymal cell adhesion, proliferation, and maturation on P15 tethered to a titanium (Ti-P15) surface. P15 peptide was covalently bonded to titanium alloy surfaces and incubated with osteoblast like cells. Cell toxicity, adhesion, spreading, and differentiation was then evaluated. Real-time quantitative PCR, Western blot analysis, and fluorescent immunohistochemistry was performed to measure osteoblast gene expression and differentiation. There was no evidence of toxicity. Significant increases in early cell attachment, spreading, and proliferation were observed on the Ti-P15 surface. Increased filapodial attachments, α(2) integrin expression, and phosphorylated focal adhesion kinase immunostaining indicated activation of integrin signaling pathways. qRT-PCR analysis indicated there was significant increase in osteogenic differentiation markers in cells grown on Ti-P15 compared to control-Ti. Western blotting confirmed these findings. Surface modification of titanium with P15 significantly increased cell attachment, spreading, osteogenic gene expression, and differentiation. Results of this study suggest that Ti-P15 has the potential to safely enhance bone formation and promote osseointegration of titanium implants.

Osteoblast Attachment on Biomaterials as a Function of Surface Charge

Bioactive materials such as calcium phosphate ceramics and bioactive glasses enhance bone tissue formation and then bond to bone tissue. In our work, we question what particular surface feature or features of bioactive materials are responsible for the bone tissue response. In this study we have uncoupled surface charge from surface chemistry, energy, and topography and have examined osteoblast adhesion to titanium surfaces of varying surface charge. We have shown that a negative surface charge promotes osteoblast adhesion by approximately 60% over a neutral surface and that conversely, a positive surface charge inhibits osteoblast adhesion by about 20%. Continued examination of surface characteristics that control cellular responses are warranted with the eventual goal of applying those desirable surface characteristics to any structural biomaterial for bone implant or tissue engineering applications.

Factors related to diabetic clients' knowledge

Conditions facilitating diabetics' learning were sought. Diabetic clients ( N = 114) from five hospitals in Western United States were studied to determine relationships between clients' knowledge, demographic descriptors, and various teaching approaches. Relationships were analyzed using correlation, multiple correlation and t tests. High pretest scores, as determined by multiple regression ( R .64), were obtained by clients who: (a) were better educated, (b) had obtained information in a hospital, (c) had diabetes longer, and (d) were younger. High posttest scores, determined by multiple regression ( R .53), were obtained by clients who: (a) were better educated, (b) were younger, (c) obtained diabetic information on an outpatient basis, and (d) had read more written material about diabetes. High difference scores, determined by multiple regression ( R .40), were obtained by clients who: (a) were more recently diagnosed, (b) received instruction in an outpatient course, and (c) had less formal education. Knowledge scores of clients who received instruction in the hospital or on an outpatient basis were not different at pretest but were at posttest. Diabetic clients learned more about management of their disease in classes taught after hospitalization.