Addressing the need for preclinical study of penile prosthesis infection: a new animal model and narrative review.

Background and Objective: Erectile dysfunction (ED) is a common condition in men, and many patients refractory to conservative treatment may undergo penile prostheses (PPs) placement. The primary concern following PP implantation is device infection. Although antibiotic and hydrophilic coatings have reduced the incidence of inflatable PP (IPP) infections, there remains room for improvement. Optimization of PP outcomes requires a practical in vivo model to better understand mechanisms of infection and to test new infection control strategies. We aimed to describe a new rabbit model which contains a functional IPP and review previously reported animal PP models. Methods: An IPP was placed into rabbit flanks and cycled for functionality testing. Rabbits were evaluated for signs of pain and distress over 14 days. Separately, narrative review methodology was utilized to search the PubMed and Scopus databases for all publications through March 21, 2023, which studied PP within an in vivo setting. Three independent reviewers ultimately selected 12 papers from 1992-2021 for inclusion. Key Content and Findings: Several animal studies highlighted the initial functionality or feasibility of devices for ED before their introduction in the clinical setting. There are several subsequent studies aimed at optimizing the type of antibiotic use or coating material using segments of PP material in an in vivo setting. However, the literature lacks a contemporary animal model containing a functional IPP. Our novel rabbit model offers a safe, practical way to implant a functioning IPP and investigate new perioperative infection prevention and treatment strategies before trials in the clinical setting. Conclusions: Animal models have played a key role in testing medical devices, including PPs, prior to their clinical introduction. Our review uncovered no modern animal studies involving placement of a functional PP. A new animal model can facilitate study of evolving microorganism profiles, novel methods to enhance antibiotic delivery, and proposed treatment options.

The 2023 Orthopaedic Research Society International Consensus Meeting on musculoskeletal infection.

The Orthopaedic Research Society's Research Interest Group completed its international consensus meeting (ICM) on musculoskeletal infections (MSKI) following the 2023 Annual Meeting. The work products from this ICM include the 65 questions with recommendation and rationale, and the voting results from the 72 delegates. There are also five Consensus Articles in this issue of the Journal of Orthopaedic Research from the ICM Sections: Host Immunity, Established Infection-Treatment, Clinical Questions not addressed by the prior MSKI ICMs, In Vitro, and Animal Models. This Introduction summarizes the 3-year Delphi process used by the ICM with timelines and critical milestones. It also highlights several challenges that had to be addressed, and a large body of work that remains.

The 2023 Orthopedic Research Society's international consensus meeting on musculoskeletal infection: Summary from the in vitro section.

Antimicrobial strategies for musculoskeletal infections are typically first developed with in vitro models. The In Vitro Section of the 2023 Orthopedic Research Society Musculoskeletal Infection international consensus meeting (ICM) probed our state of knowledge of in vitro systems with respect to bacteria and biofilm phenotype, standards, in vitro activity, and the ability to predict in vivo efficacy. A subset of ICM delegates performed systematic reviews on 15 questions and made recommendations and assessment of the level of evidence that were then voted on by 72 ICM delegates. Here, we report recommendations and rationale from the reviews and the results of the internet vote. Only two questions received a ≥90% consensus vote, emphasizing the disparate approaches and lack of established consensus for in vitro modeling and interpretation of results. Comments on knowledge gaps and the need for further research on these critical MSKI questions are included.

Multiple Sterile Withdrawals from Iohexol Bottles Does Not Increase Contamination Risk.

BACKGROUND: There is a global shortage of iohexol contrast media, commonly used in epidural injections, as a result of lockdown and decreased production due to COVID-19. Iohexol bottles are designated for single use, which, depending on the vials available, often leads to wasting up to 95% of this limited resource. However, avoiding multiple withdrawals may be unnecessary if withdrawing multiple times using sterile technique does not increase the risk for contamination. OBJECTIVES: The purpose of our study is to determine whether multiple withdrawals from iohexol injection bottles using a sterile technique poses a greater risk of introducing contaminants than a single withdrawal. Furthermore, we wish to determine the extent to which bacteria can survive and grow in the contrast media. STUDY DESIGN: Experimental. SETTING: Outpatient fluoroscopic suite and laboratory. METHODS: Twenty-one 100 mL 300 mg(iodine)/mL iohexol injection bottles, after one clinical use, were tested after the first and last withdrawals (withdrawal one and withdrawal 9 or 10) for bacterial and fungal specimens using culture media and 3M™ Petrifilms™. To determine the ability of methicillin-susceptible Staphylococcus aureus (MSSA) to survive or grow in the media, MSSA was added to different concentrations (0, 25, 50, 75, and 100%) of iohexol contrast media. RESULTS: There was no growth observed in cultures or on Petrifilms among the first and last draws of any of the samples. When bacteria were grown in different dilutions of the media, there was a significant, approximately one log decrease in counts from 0% contrast media to 100% contrast media (8.4 x 108 vs 5.6 x 107, P < 0.01). LIMITATIONS: Our study is limited in the number of samples tested and would benefit from additional investigation before consideration of clinical application. CONCLUSIONS: Our results suggest that single-use 300 iohexol bottles may be reusable and that the contrast media is mildly antimicrobial, but not enough to retard contamination. In setting of shortages, contrast media bottles can safely be reused. This is valuable for conserving resources and limiting unnecessary health care-associated costs.

In Vitro and In Vivo Evaluation of Ultrasound-Triggered Release From Novel Spinal Device.

OBJECTIVES: Bacterial infection following spinal fusion is a major clinical concern with up to 20% incidence. An ultrasound-triggered bulk-release system to combat postsurgical bacterial survival was designed and evaluated. METHODS: Polylactic acid (PLA) clips were loaded with vancomycin (VAN) and microbubbles (Sonazoid, GE HealthCare) in vitro. Stability was determined over 14 days. VAN-loaded clips were submerged in water and insonated using a Logiq E10 scanner (GE HealthCare) with a curvilinear C6 probe. Doppler-induced VAN release was quantified using spectrophotometry. For in vivo testing, clips were loaded with methylene blue (MeB) solution and Sonazoid. These clips were implanted into a rabbit along the spine at L2 and L5, as well as a pig at L1 and L3, then insonated in Doppler mode using the C6 probe. RESULTS: Sonazoid microbubbles were better preserved when incubated in VAN compared with distilled water at 4°C, 25°C, and 37°C incubation temperatures (P = .0131). Contrast enhancement was observed from both solutions when incubated at 4°C storage conditions. Insonated clips achieved average cumulative VAN release of 101.8 ± 2.8% (81.4 ± 2.8 mg) after 72 hours. Uninsonated clips had only 0.3 ± 0.1% (0.3 ± 0.1 mg) average cumulative VAN release (P < .0001). Clips retrieved from the rabbit did not rupture with insonation nor produce MeB staining of surrounding tissues. In the pig, the PLA film was visibly ruptured and MeB tissue was observed following insonation, whereas the uninsonated clip was intact. CONCLUSION: These results demonstrate ultrasound-triggered release of an encapsulated prophylactic solution and provide an important proof-of-concept for continuing large animal evaluations for translational merit.

Cold atmospheric pressure plasma-antibiotic synergy in Pseudomonas aeruginosa biofilms is mediated via oxidative stress response.

Cold atmospheric-pressure plasma (CAP) has emerged as a potential alternative or adjuvant to conventional antibiotics for the treatment of bacterial infections, including those caused by antibiotic-resistant pathogens. The potential of sub-lethal CAP exposures to synergise conventional antimicrobials for the eradication of Pseudomonas aeruginosa biofilms is investigated in this study. The efficacy of antimicrobials following or in the absence of sub-lethal CAP pre-treatment in P. aeruginosa biofilms was assessed. CAP pre-treatment resulted in an increase in both planktonic and biofilm antimicrobial sensitivity for all three strains tested (PAO1, PA14, and PA10548), with both minimum inhibitory concentrations (MICs) and minimum biofilm eradication concentrations (MBECs) of individual antimicrobials, being significantly reduced following CAP pre-treatment of the biofilm (512-fold reduction with ciprofloxacin/gentamicin; and a 256-fold reduction with tobramycin). At all concentrations of antimicrobial used, the combination of sub-lethal CAP exposure and antimicrobials was effective at increasing time-to-peak metabolism, as measured by isothermal microcalorimetry, again indicating enhanced susceptibility. CAP is known to damage bacterial cell membranes and DNA by causing oxidative stress through the in situ generation of reactive oxygen and nitrogen species (RONS). While the exact mechanism is not clear, oxidative stress on outer membrane proteins is thought to damage/perturb cell membranes, confirmed by ATP and LDH leakage, allowing antimicrobials to penetrate the bacterial cell more effectively, thus increasing bacterial susceptibility. Transcriptomic analysis, reveals that cold-plasma mediated oxidative stress caused upregulation of P. aeruginosa superoxide dismutase, cbb3 oxidases, catalases, and peroxidases, and upregulation in denitrification genes, suggesting that P. aeruginosa uses these enzymes to degrade RONS and mitigate the effects of cold plasma mediated oxidative stress. CAP treatment also led to an increased production of the signalling molecule ppGpp in P. aeruginosa, indicative of a stringent response being established. Although we did not directly measure persister cell formation, this stringent response may potentially be associated with the formation of persister cells in biofilm cultures. The production of ppGpp and polyphosphate may be associated with protein synthesis inhibition and increase efflux pump activity, factors which can result in antimicrobial tolerance. The transcriptomic analysis also showed that by 6 h post-treatment, there was downregulation in ribosome modulation factor, which is involved in the formation of persister cells, suggesting that the cells had begun to resuscitate/recover. In addition, CAP treatment at 4 h post-exposure caused downregulation of the virulence factors pyoverdine and pyocyanin; by 6 h post-exposure, virulence factor production was increasing. Transcriptomic analysis provides valuable insights into the mechanisms by which P. aeruginosa biofilms exhibits enhanced susceptibility to antimicrobials. Overall, these findings suggest, for the first time, that short CAP sub-lethal pre-treatment can be an effective strategy for enhancing the susceptibility of P. aeruginosa biofilms to antimicrobials and provides important mechanistic insights into cold plasma-antimicrobial synergy. Transcriptomic analysis of the response to, and recovery from, sub-lethal cold plasma exposures in P. aeruginosa biofilms improves our current understanding of cold plasma biofilm interactions.

Berberine disrupts staphylococcal proton motive force to cause potent anti-staphylococcal effects in vitro.

The presence of antibiotic resistance has increased the urgency for more effective treatments of bacterial infections. Biofilm formation has complicated this issue as biofilm bacteria become tolerant to antibiotics due to environmental factors such as nutrient deprivation and adhesion. In septic arthritis, a disease with an 11% mortality rate, bacteria in synovial fluid organize into floating, protein-rich, bacterial aggregates (mm-cm) that display depressed metabolism and antibiotic tolerance. In this study, Staphylococcus aureus (S. aureus), which is the most common pathogen in septic arthritis, was tested against different inhibitors that modulate bacterial surface protein availability and that should decrease bacterial aggregation. One of these, berberine, a quaternary ammonium compound, was found to reduce bacterial counts by 3-7 logs in human synovial fluid (aggregating medium) with no effect in tryptic soy broth (TSB, non-aggregating). Unlike traditional antibiotics, the bactericidal activity of berberine appeared to be independent of bacterial metabolism. To elucidate the mechanism, we used synovial fluid fractionation, targeted MRSA transposon insertion mutants, dyes to assess changes in membrane potential (DiSC3(5)) and membrane permeability (propidium iodide (PI)), colony counting, and fluorescence spectroscopy. We showed that berberine's activity was dependent on an alkaline pH and berberine killed both methicillin-sensitive S. aureus and MRSA in alkaline media (pH 8.5-9.0; p < 0.0001 vs. same pH controls). Under these alkaline conditions, berberine localized to S. aureus where berberine was isolated in cytoplasmic (∼95%) and DNA (∼5%) fractions. Importantly, berberine increased bacterial cell membrane permeability, and disrupted the proton motive force, suggesting a mechanism whereby it may be able to synergize with other antibacterial compounds under less harsh conditions. We suggest that berberine, which is cheap and readily available, can be made into an effective treatment.

Microbubble cavitation restores Staphylococcus aureus antibiotic susceptibility in vitro and in a septic arthritis model.

Treatment failure in joint infections is associated with fibrinous, antibiotic-resistant, floating and tissue-associated Staphylococcus aureus aggregates formed in synovial fluid (SynF). We explore whether antibiotic activity could be increased against Staphylococcus aureus aggregates using ultrasound-triggered microbubble destruction (UTMD), in vitro and in a porcine model of septic arthritis. In vitro, when bacterially laden SynF is diluted, akin to the dilution achieved clinically with lavage and local injection of antibiotics, amikacin and ultrasound application result in increased bacterial metabolism, aggregate permeabilization, and a 4-5 log decrease in colony forming units, independent of microbubble destruction. Without SynF dilution, amikacin + UTMD does not increase antibiotic activity. Importantly, in the porcine model of septic arthritis, no bacteria are recovered from the SynF after treatment with amikacin and UTMD-ultrasound without UTMD is insufficient. Our data suggest that UTMD + antibiotics may serve as an important adjunct for the treatment of septic arthritis.

Evaluation of bacterial attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis.

The design of biomaterials to regenerate bone is likely to increasingly require modifications that reduce bacterial attachment and biofilm formation as infection during wound regeneration can significantly impede tissue repair and typically requires surgical intervention to restart the healing process. Further, much research on infection prevention in bone biomaterials has focused on modeling of non-resorbable metal alloy materials, whereas an expanding direction of bone regeneration has focused on development of bioresorbable materials. This represents a need for the prevention and understanding of infection in resorbable biomaterials. Here, we investigate the ability of a mineralized collagen biomaterial to natively resist infection and examine how the addition of manuka honey, previously identified as an antimicrobial agent, affects gram positive and negative bacterial colonization and mesenchymal stem cell osteogenesis and vasculature formation. We incorporate manuka honey into these scaffolds via either direct fabrication into the scaffold microarchitecture or via soaking the scaffold in a solution of manuka honey after fabrication. Direct incorporation results in a change in the surface characteristics and porosity of mineralized collagen scaffolds. Soaking scaffolds in honey concentrations higher than 10% had significant negative effects on mesenchymal stem cell metabolic activity. Soaking or incorporating 5% honey had no impact on endothelial cell tube formation. Although solutions of 5% honey reduced metabolic activity of mesenchymal stem cells, MSC-seeded scaffolds displayed increased calcium and phosphorous mineral formation, osteoprotegerin release, and alkaline phosphatase activity. Bacteria cultured on mineralized collagen scaffolds demonstrated surfaces covered in bacteria and no method of preventing infection, and using 10 times the minimal inhibitory concentration of antibiotics did not completely kill bacteria within the mineralized collagen scaffolds, indicating bioresorbable scaffold materials may act to shield bacteria from antibiotics. The addition of 5% manuka honey to scaffolds was not sufficient to prevent P. aeruginosa attachment or consistently reduce the activity of methicillin resistant staphylococcus aureus, and concentrations above 7% manuka honey are likely necessary to impact MRSA. Together, our results suggest bioresorbable scaffolds may create an environment conducive to bacterial growth, and potential trade-offs exist for the incorporation of low levels of honey in scaffolds to increase osteogenic potential of osteoprogenitors while high-levels of honey may be sufficient to reduce gram positive or negative bacteria activity but at the cost of reduced osteogenesis.

A scoping review of penile implant biofilms-what do we know and what remains unknown?

Background: Penile prosthesis (PP) is a gold standard for treatment of erectile dysfunction given its reliability and efficacy. Infection remains the most feared complication of prosthetic surgery, which usually results in device removal, and places a significant economic burden on the healthcare system. While biofilms have shown to support the persistence of microorganisms, the degree by which this matrix is truly pathogenic remains unknown given its high prevalence even in asymptomatic patients. We aim to review and summarize the current literature pertaining to biofilm formation in the setting of PP surgeries in clinically infected and non-infected cases. Methods: Searches were performed in the MEDLINE online database through PubMed using a combination of keywords "penile prosthetic" OR "penile prosthesis" OR "penile implant" AND "biofilm" OR "revision" OR "removal" OR "infection" OR "explant". Eleven articles met inclusion criteria. There were only three studies that explicitly listed the number of biofilms identified in their cohort, but we also included eight articles that mentioned swabbing and culturing of any bacterial biofilm during revision procedures for both clinically infected and non-infected implants. Results: Infected PP yielded a 11-100% rate of biofilm presence, while non-infected PP yielded a 3-70% rate of biofilm presence. Time to reoperation from initial PP placement were also largely variable, ranging from 2 weeks to over 2 years. Coagulase-negative staphylococcus (i.e., Staphylococcus epidermidis) were the most commonly reported organisms among non-infected implants, however, newer studies have identified a change towards more virulent organisms. Conclusions: Since the advent of PP surgery, diabetes control, revision washout protocols and antibiotic-impregnated devices have led to an overall decrease in biofilm formation and infectious complications. There is an overall paradigm shift in microbial profiles with more virulent organisms, such as Escherichia coli, Pseudomonas aeruginosa, Enterococcus species, and even fungal species beginning to replace the more common coagulase-negative staphylococcal species, especially in clinically infected implants. Additional studies are necessary to define the significance of bacterial presence in biofilms using impactful technologies such as next-generation sequencing. Currently, preliminary and experimental biofilm-control strategies are also underway to further address this clinical issue.

A Platelet-Rich Plasma-Derived Biologic Clears Staphylococcus aureus Biofilms While Mitigating Cartilage Degeneration and Joint Inflammation in a Clinically Relevant Large Animal Infectious Arthritis Model.

The leading cause of treatment failure in Staphylococcus aureus infections is the development of biofilms. Biofilms are highly tolerant to conventional antibiotics which were developed against planktonic cells. Consequently, there is a lack of antibiofilm agents in the antibiotic development pipeline. To address this problem, we developed a platelet-rich plasma (PRP)-derived biologic, termed BIO-PLY (for the BIOactive fraction of Platelet-rich plasma LYsate) which has potent in vitro bactericidal activity against S. aureus synovial fluid free-floating biofilm aggregates. Additional in vitro studies using equine synoviocytes and chondrocytes showed that BIO-PLY protected these cells of the joint from inflammation. The goal of this study was to test BIO-PLY for in vivo efficacy using an equine model of infectious arthritis. We found that horses experimentally infected with S. aureus and subsequently treated with BIO-PLY combined with the antibiotic amikacin (AMK) had decreased bacterial concentrations within both synovial fluid and synovial tissue and exhibited lower systemic and local inflammatory scores compared to horses treated with AMK alone. Most importantly, AMK+BIO-PLY treatment reduced the loss of infection-associated cartilage proteoglycan content in articular cartilage and decreased synovial tissue fibrosis and inflammation. Our results demonstrate the in vivo efficacy of AMK+BIO-PLY and represents a new approach to restore and potentiate antimicrobial activity against synovial fluid biofilms.

Making waves: how ultrasound-targeted drug delivery is changing pharmaceutical approaches.

Administration of drugs through oral and intravenous routes is a mainstay of modern medicine, but this approach suffers from limitations associated with off-target side effects and narrow therapeutic windows. It is often apparent that a controlled delivery of drugs, either localized to a specific site or during a specific time, can increase efficacy and bypass problems with systemic toxicity and insufficient local availability. To overcome some of these issues, local delivery systems have been devised, but most are still restricted in terms of elution kinetics, duration, and temporal control. Ultrasound-targeted drug delivery offers a powerful approach to increase delivery, therapeutic efficacy, and temporal release of drugs ranging from chemotherapeutics to antibiotics. The use of ultrasound can focus on increasing tissue sensitivity to the drug or actually be a critical component of the drug delivery. The high spatial and temporal resolution of ultrasound enables precise location, targeting, and timing of drug delivery and tissue sensitization. Thus, this noninvasive, non-ionizing, and relatively inexpensive modality makes the implementation of ultrasound-mediated drug delivery a powerful method that can be readily translated into the clinical arena. This review covers key concepts and areas applied in the design of different ultrasound-mediated drug delivery systems across a variety of clinical applications.

An Evaluation of the Bacterial Adherence to Casting Materials.

INTRODUCTION:  The purpose of this study was to evaluate bacterial adherence to common casting materials including plaster of Paris (plaster), fiberglass, three-dimensional (3D) printed plastic, and silicone-coated 3D printed plastic. METHODS: The minimal inhibitory concentration of a phosphate-free detergent (Palmolive) needed to achieve total bacterial kill off was determined. 3D printed polylactic acid plastic samples were coated with silicone. Plaster, fiberglass, plastic, and silicone-coated plastic samples were inoculated with Staphylococcus aureus. After bacterial inoculation, scanning electron microscopy of the samples was performed to visualize bacterial adherence to the materials' surface. Using either sterile water or a 5% detergent solution, the materials were subjected to washings. Each material was run in 30 replicates: 6 without washing, 6 with sterile water for 1 minute, 6 with detergent for 1 minute, 6 with sterile water for 3 minutes, and 6 with detergent for 3 minutes. The replicates that did not undergo a washing trial represented the initial bacterial inoculation. Samples were then rinsed and sonicated in polysorbate to isolate the remaining adherent bacteria on the materials' surface. The sonicated solutions were plated, incubated, and counted for quantification of colony forming units (CFU) of bacteria. This protocol was repeated for a total of four trials. RESULTS: During inoculation, there were significantly less bacteria that adhered to silicone-coated 3D printed plastic (58879 CFU) compared to plastic (217479 CFU), plaster (140063 CFU), and fiberglass (550546 CFU). Silicone coating showed further superiority. Silicone-coated 3D printed plastic was able to be decontaminated as demonstrated by significantly fewer remaining bacteria (9.3%) on its surface after being washed with a 5% detergent solution (1797 CFU) compared to sterile water (19321 CFU). The mean remaining bacteria on silicone-coated 3D printed plastic was significantly less than that remaining on all other materials when washed with either sterile water or a detergent solution for both durations of 1 minute and 3 minutes. CONCLUSIONS: The current study demonstrates that significantly less bacteria adhere to the surface of 3D printed plastic with silicone coating showing added protection and that this material can be decontaminated to a greater degree with washing than conventional casting materials. These results provide evidence that 3D printed casts can be washed and successfully decontaminated during a patient's period of immobilization, which is advantageous especially during an infectious crisis such as the coronavirus disease 2019 (COVID-19) pandemic.

Staphylococcus aureus Floating Biofilm Formation and Phenotype in Synovial Fluid Depends on Albumin, Fibrinogen, and Hyaluronic Acid.

Biofilms are typically studied in bacterial media that allow the study of important properties such as bacterial growth. However, the results obtained in such media cannot take into account the bacterial localization/clustering caused by bacteria-protein interactions in vivo and the accompanying alterations in phenotype, virulence factor production, and ultimately antibiotic tolerance. We and others have reported that methicillin-resistant or methicillin-susceptible Staphylococcus aureus (MRSA or MSSA, respectively) and other pathogens assemble a proteinaceous matrix in synovial fluid. This proteinaceous bacterial aggregate is coated by a polysaccharide matrix as is characteristic of biofilms. In this study, we identify proteins important for this aggregation and determine the concentration ranges of these proteins that can reproduce bacterial aggregation. We then test this protein combination for its ability to cause marked aggregation, antibacterial tolerance, preservation of morphology, and expression of the phenol-soluble modulin (PSM) virulence factors. In the process, we create a viscous fluid that models bacterial behavior in synovial fluid. We suggest that our findings and, by extension, use of this fluid can help to better model bacterial behavior of new antimicrobial therapies, as well as serve as a starting point to study host protein-bacteria interactions characteristic of physiological fluids.

Biomolecules as Model Indicators of In Vitro and In Vivo Cold Plasma Safety.

The potential applications for cold plasma in medicine are extensive, from microbial inactivation and induction of apoptosis in cancer cells to stimulating wound healing and enhancing the blood coagulation cascade. The safe bio-medical application of cold plasma and subsequent effect on complex biological pathways requires precision and a distinct understanding of how physiological redox chemistry is manipulated. Chemical modification of biomolecules such as carbohydrates, proteins, and lipids treated with cold plasma have been characterized, however, the context of how alterations of these molecules affect cell behavior or in vivo functionality has not been determined. Thus, this study examines the cytotoxic and mutagenic effects of plasma-treated molecules in vitro using CHO-K1 cells and in vivo in Galleria mellonella larvae. Specifically, albumin, glucose, cholesterol, and arachidonic acid were chosen as representative biomolecules, with established involvement in diverse bioprocesses including; cellular respiration, intracellular transport, cell signaling or membrane structure. Long- and short-term effects depended strongly on the molecule type and the treatment milieu indicating the impact of chemical and physical modifications on downstream biological pathways. Importantly, absence of short-term toxicity did not always correlate with absence of longer-term effects, indicating the need to comprehensively assess ongoing effects for diverse biological applications.

Bacterial toxins in musculoskeletal infections.

Musculoskeletal infections (MSKIs) remain a major health burden in orthopaedics. Bacterial toxins are foundational to pathogenesis in MSKI, but poorly understood by the community of providers that care for patients with MSKI, inducing an international group of microbiologists, infectious diseases specialists, orthopaedic surgeons and biofilm scientists to review the literature in this field to identify key topics and compile the current knowledge on the role of toxins in MSKI, with the goal of illuminating potential impact on biofilm formation and dispersal as well as therapeutic strategies. The group concluded that further research is needed to maximize our understanding of the effect of toxins on MSKIs, including: (i) further research to identify the roles of bacterial toxins in MSKIs, (ii) establish the understanding of the importance of environmental and host factors and in vivo expression of toxins throughout the course of an infection, (iii) establish the principles of drug-ability of antitoxins as antimicrobial agents in MSKIs, (iv) have well-defined metrics of success for antitoxins as antiinfective drugs, (v) design a cocktail of antitoxins against specific pathogens to (a) inhibit biofilm formation and (b) inhibit toxin release. The applicability of antitoxins as potential antimicrobials in the era of rising antibiotic resistance could meet the needs of day-to-day clinicians.

Minimizing Penile Prosthesis Implant Infection: What Can We Learn From Orthopedic Surgery?

The implantation of penile protheses for the surgical treatment of erectile dysfunction has risen in popularity over the past several decades. Considerable advances have been made in surgical protocol and device design, specifically targeting infection prevention. Despite these efforts, device infection remains a critical problem, which causes significant physical and emotional burden to the patient. The aim of this review is to broaden the discussion of best practices by not only examining practices in urology, but additionally delving into the field of orthopedic surgery to identify techniques and approaches that may be applied to penile prothesis surgery.

Acoustic Parameters for Optimal Ultrasound-Triggered Release from Novel Spinal Hardware Devices.

Post-operative infection is a catastrophic complication of spinal fusion surgery, with rates as high as 10%, and existing preventative measures (i.e., peri-operative antibiotics) are only partially successful. To combat this clinical problem, we have designed a drug delivery system around polyether ether ketone clips to be used for prophylactic post-surgical release of antibiotics upon application of ultrasound. The overall hypothesis is that antimicrobial release from this system will aggressively combat post-surgical bacterial survival. This study investigated a set of acoustic parameters optimized for in vitro ultrasound-triggered coating rupture and subsequent release of encapsulated prophylactic antibiotics. We determined that a transducer frequency of 1.7 MHz produced the most consistent burst release and that, at this frequency, a pulse repetition frequency of 6.4 kHz and acoustic output power of 100% (3.41 MPa) produced the greatest release, representing an important proof of principle and the basis for continued development of this novel drug delivery system.

Equine or porcine synovial fluid as a novel ex vivo model for the study of bacterial free-floating biofilms that form in human joint infections.

Bacterial invasion of synovial joints, as in infectious or septic arthritis, can be difficult to treat in both veterinary and human clinical practice. Biofilms, in the form of free-floating clumps or aggregates, are involved with the pathogenesis of infectious arthritis and periprosthetic joint infection (PJI). Infection of a joint containing an orthopedic implant can additionally complicate these infections due to the presence of adherent biofilms. Because of these biofilm phenotypes, bacteria within these infected joints show increased antimicrobial tolerance even at high antibiotic concentrations. To date, animal models of PJI or infectious arthritis have been limited to small animals such as rodents or rabbits. Small animal models, however, yield limited quantities of synovial fluid making them impractical for in vitro research. Herein, we describe the use of ex vivo equine and porcine models for the study of synovial fluid induced biofilm aggregate formation and antimicrobial tolerance. We observed Staphylococcus aureus and other bacterial pathogens adapt the same biofilm aggregate phenotype with significant antimicrobial tolerance in both equine and porcine synovial fluid, analogous to human synovial fluid. We also demonstrate that enzymatic dispersal of synovial fluid aggregates restores the activity of antimicrobials. Future studies investigating the interaction of bacterial cell surface proteins with host synovial fluid proteins can be readily carried out in equine or porcine ex vivo models to identify novel drug targets for treatment of prevention of these difficult to treat infectious diseases.