Prosthesis infections after orthopedic joint replacement: the possible role of bacterial biofilms

Does time of intraoperative exposure to the aerobiome increase microbial growth on inflatable penile prostheses?

Inflatable penile prosthesis (IPP) implantation is a surgical approach for the management of erectile dysfunction (ED). A feared complication is IPP infection, and increased operative time is a risk factor for infection. Exposure of an IPP implant to ambient air in the operating room (OR aerobiome) is thought to contribute to risk of infection from increased operative time, but this is not well-supported. The objective of this study was to evaluate if exposure to the OR aerobiome increased microbial colonization of IPPs. This was an ex vivo study using an uncoated IPP, observing standard surgical sterility and OR conditions. A sterile swab was collected every 30 min for 3 h from each IPP component. Positive controls consisted of swabs exposed to unprepped scrotal skin during in-office vasectomies. All swabs underwent quantitative polymerase chain reaction (qPCR) and next generation sequencing (NGS). Bioinformatic processing was carried out and taxonomic assignment was performed. No microbial growth was detected on any component of the IPPs at any time point, while positive control swabs all detected various skin flora, including bacterial and fungal growth. These findings suggest that exposure to the OR aerobiome does not increase the risk of IPP microbial colonization, at least within a 3-hour period. Further in vivo studies are needed.

Zinc- and Fluoride-Releasing Bioactive Glass as a Novel Bone Substitute

Bioglass 45S5, a silica-based glass, has pioneered a new field of biomaterials. Bioglass 45S5 promotes mineralization through calcium ion release and is widely used in the dental field, including toothpaste formulations. However, the use of Bioglass 45S5 for bone grafting is limited owing to the induction of inflammation, as well as reduced degradation and ion release. Phosphate-based glasses exhibit higher solubility and ion release than silica-based glass. Given that these glasses can be synthesized at low temperatures (approximately 1,000°C), they can easily be doped with various metal oxides to confer therapeutic properties. Herein, we fabricated zinc- and fluoride-doped phosphate-based glass (multicomponent phosphate [MP] bioactive glass) and further doped aluminum oxide into the MP glass (4% Al-MP glass) to overcome the striking solubility of phosphate-based glass. Increased amounts of zinc and fluoride ions were detected in water containing the MP glass. Doping of aluminum oxide into the MP glass suppressed the striking dissolution in water, with 4% Al-MP glass exhibiting the highest stability in water. Compared with Bioglass 45S5, 4% Al-MP glass in water had a notably reduced particle size, supporting the abundant ion release of 4% Al-MP glass. Compared with Bioglass 45S5, 4% Al-MP glass enhanced the osteogenesis of mouse bone marrow-derived mesenchymal stem cells. Mouse macrophages cultured with 4% Al-MP glass displayed enhanced induction of anti-inflammatory M2 macrophages and reduced proinflammatory M1 macrophages, indicating M2 polarization. Upon implanting 4% Al-MP glass or Bioglass 45S5 in a mouse calvarial defect, 4% Al-MP glass promoted significant bone regeneration when compared with Bioglass 45S5. Hence, we successfully fabricated zinc- and fluoride-releasing bioactive glasses with improved osteogenic and anti-inflammatory properties, which could serve as a promising biomaterial for bone regeneration.

Real-World Evidence of the Impact of a Novel Surgical Irrigant on Surgical Site Infections in Primary Total Knee Arthroplasty Performed at an Ambulatory Surgery Center

Background: Total knee arthroplasty (TKA) is one of the most common inpatient and outpatient surgical procedures performed in the United States and is predicted to increase 401% by 2040. Surgical site infections (SSIs) at an incidence rate of approximately 2% are costly post-operative complications in TKA. Intra-operative surgical irrigants are used to decrease contaminating microbial bioburden within the surgical site to prevent SSI. The primary objective of this retrospective study was to evaluate the impact of a novel surgical irrigant called XPERIENCE® Advanced Surgical Irrigation (XP; Next Science, Jacksonville, FL) on SSI incidence in primary TKA performed at an ambulatory surgery center (ASC). Patients and Methods: Primary TKAs were performed at a free-standing ASC. The novel surgical irrigant was used intra-operatively to rinse away debris and micro-organisms from the surgical site. Retrospective data collation included SSI rates, complication rates, and re-admissions due to SSI within 90 days of index surgery. Results: Among the 524 primary TKA surgeries, one peri-prosthetic joint infection (PJI) was diagnosed within 90 days of index surgery and one superficial incisional SSI was diagnosed within 30 days of index surgery. The PJI was attributed to an exogenously acquired upper respiratory tract infection rather than due to the failure of intra-operative regimes. The 0.19% PJI incidence rate indicated significant efficacy of XP in decreasing PJI. An overall complication rate of 7.82% was noted with none of the complications associated with usage of the novel surgical irrigant. Conclusions: XPERIENCE is a promising intra-operative antimicrobial irrigant that can be easily incorporated into a broader infection prevention strategy.

Tailored Coatings for Enhanced Performance of Zinc-Magnesium Alloys in Absorbable Implants

Absorbable metals exhibit potential for next-generation temporary medical implants, dissolving safely in the body during tissue healing and regeneration. Their commercial incorporation could substantially diminish the need for additional surgeries and complications that are tied to permanent devices. Despite extensive research on magnesium (Mg) and iron (Fe), achieving the optimal combination of mechanical properties, biocompatibility, and controlled degradation rate for absorbable implants remains a challenge. Zinc (Zn) and Zn-based alloys emerged as an attractive alternative for absorbable implants, due to favorable combination of in vivo biocompatibility and degradation behavior. Moreover, the development of suitable coatings can enhance their biological characteristics and tailor their degradation process. In this work, four different biodegradable coatings (based on zinc phosphate (ZnP), collagen (Col), and Ag-doped bioactive glass nanoparticles (AgBGNs)) were synthesized by chemical conversion, spin-coating, or a combination of both on Zn-3Mg substrates. This study assessed the impact of the coatings on in vitro degradation behavior, cytocompatibility, and antibacterial activity. The ZnP-coated samples demonstrated controlled weight loss and a decreased corrosion rate over time, maintaining a physiological pH. Extracts from the uncoated, ZnP-coated, and Col-AgBGN-coated samples showed higher cell viability with increasing concentration. Bacterial viability was significantly impaired in all coated samples, particularly in the Col-AgBGN coating. This study showcases the potential of a strategic material-coating combination to effectively tackle multiple challenges encountered in current medical implant technologies by modifying the properties of absorbable metals to tailor patient treatments.

Antibiofilm activity of marine microbial natural products: potential peptide- and polyketide-derived molecules from marine microbes toward targeting biofilm-forming pathogens

Controlling and treating biofilm-related infections is challenging because of the widespread presence of multidrug-resistant microbes. Biofilm, a naturally occurring matrix of microbial aggregates, has developed intricate and diverse resistance mechanisms against many currently used antibiotics. This poses a significant problem, especially for human health, including clinically chronic infectious diseases. Thus, there is an urgent need to search for and develop new and more effective antibiotics. As the marine environment is recognized as a promising reservoir of new biologically active molecules with potential pharmacological properties, marine natural products, particularly those of microbial origin, have emerged as a promising source of antibiofilm agents. Marine microbes represent an untapped source of secondary metabolites with antimicrobial activity. Furthermore, marine natural products, owing to their self-defense mechanisms and adaptation to harsh conditions, encompass a wide range of chemical compounds, including peptides and polyketides, which are primarily found in microbes. These molecules can be exploited to provide novel and unique structures for developing alternative antibiotics as effective antibiofilm agents. This review focuses on the possible antibiofilm mechanism of these marine microbial molecules against biofilm-forming pathogens. It provides an overview of biofilm development, its recalcitrant mode of action, strategies for the development of antibiofilm agents, and their assessments. The review also revisits some selected peptides and polyketides from marine microbes reported between 2016 and 2023, highlighting their moderate and considerable antibiofilm activities. Moreover, their antibiofilm mechanisms, such as adhesion modulation/inhibition targeting biofilm-forming pathogens, quorum sensing intervention and inhibition, and extracellular polymeric substance disruption, are highlighted herein.

Modulating On-Demand Release of Vancomycin from Implant Coatings via Chemical Modification of a Micrococcal Nuclease-Sensitive Oligonucleotide Linker

Periprosthetic infections are one of the most serious complications in orthopedic surgeries, and those caused by Staphylococcus aureus (S. aureus) are particularly hard to treat due to their tendency to form biofilms on implants and their notorious ability to invade the surrounding bones. The existing prophylactic local antibiotic deliveries involve excessive drug loading doses that could risk the development of drug resistance strains. Utilizing an oligonucleotide linker sensitive to micrococcal nuclease (MN) cleavage, we previously developed an implant coating capable of releasing covalently tethered vancomycin, triggered by S. aureus-secreted MN, to prevent periprosthetic infections in the mouse intramedullary (IM) canal. To further engineer this exciting platform to meet broader clinical needs, here, we chemically modified the oligonucleotide linker by a combination of 2'-O-methylation and phosphorothioate modification to achieve additional modulation of its stability/sensitivity to MN and the kinetics of MN-triggered on-demand release. We found that when all phosphodiester bonds within the oligonucleotide linker 5'-carboxy-mCmGTTmCmG-3-acrydite, except for the one between TT, were replaced by phosphorothioate, the oligonucleotide (6PS) stability significantly increased and enabled the most sustained release of tethered vancomycin from the coating. By contrast, when only the peripheral phosphodiester bonds at the 5'- and 3'-ends were replaced by phosphorothioate, the resulting oligonucleotide (2PS) linker was cleaved by MN more rapidly than that without any PS modifications (0PS). Using a rat femoral canal periprosthetic infection model where 1000 CFU S. aureus was inoculated at the time of IM pin insertion, we showed that the prophylactic implant coating containing either 0PS- or 2PS-modified oligonucleotide linker effectively eradicated the bacteria by enabling the rapid on-demand release of vancomycin. No bacteria were detected from the explanted pins, and no signs of cortical bone changes were detected in these treatment groups throughout the 3 month follow-ups. With an antibiotic tethering dose significantly lower than conventional antibiotic-bearing bone cements, these coatings also exhibited excellent biocompatibility. These chemically modified oligonucleotides could help tailor prophylactic anti-infective coating strategies to meet a range of clinical challenges where the risks for S. aureus prosthetic infections range from transient to long-lasting.

Prosthetic joint infection caused by an imipenem-resistant Mycobacterium senegalense

Periprosthetic joint infection (PJI) remains one of the most common complications of total knee arthroplasty. Although mainly caused by Staphylococcus aureus and other Gram-positive microorganisms, occasionally, commensal or environmental bacteria are reported as causative agents of these infections. The present work aimed to report a case of PJI caused by an imipenem-resistant Mycobacterium senegalense strain. A bacterial strain isolated from the culture of intraoperative samples was observed by optical microscopy after Gram and Ziehl-Neelsen staining. The species identification was performed by mass spectrometry analysis and partial sequencing of the heat shock protein 65 (hsp65) gene. The antimicrobial profile of the clinical isolate was determined according to the Clinical and Laboratory Standards Institute. Mass spectrometry and gene sequencing analysis identified the bacterial isolate as Mycobacterium fortuitum complex and M. senegalense, respectively. The isolated was found exhibiting an imipenem-resistant profile. The accurate and timely identification, as well as investigation of the antimicrobial susceptibility profile, of fast-growing nontuberculous mycobacteria species are crucial for establishing the prompt and correct treatment of the infection, particularly in cases of patients at greater risk for opportunistic and severe infections.

Synthesis and Characterization of Thymol-Loaded Niosomal Film for the Prevention of Implant-Related Infection

Background

Infection is one of the significant challenges in medical implant-related surgeries. Despite systemic antibiotic therapies, bacterial growth after implantation may cause implant failure. Nowadays, unlike the systemic therapy, local controlled release of antibiotic agents is considered an effective approach for the prevention of implant-related infections. The present study aimed to develop a niosomal nanocarrier incorporated into fibroin films for local and continuous delivery of thymol, a natural plant-derived antimicrobial agent for preventing infections caused by implant-related.

Methods

Niosomes containing thymol were prepared by thin-film hydration technique. Thymol sustained release from the prepared films was assessed for 14 days. Antibacterial activities of the synthesized films were also evaluated by the agar diffusion technique against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus.

Results

The release behavior from the niosomal thymol films showed a sustained manner, in which the amount of the released thymol reached 40% after 14 days. The films containing thymol with and without niosome showed a significant viability against L929 fibroblast cells compared to other groups after 24 and 48 h, using MTT assay. Also, samples exhibited potent antibacterial activity against Gram-negative and Gram-positive bacteria.

Conclusion

The results of this study demonstrate that the niosomal thymol-loaded fibroin film is a promising candidate for the controlled release of thymol and prevention of implant-related infection.

Titanium surface polyethylene glycol hydrogel and gentamicin-loaded cross-linked starch microspheres release system for anti-infective drugs

OBJECTIVE

To design and construct a hydrogel drug-controlled release system loaded with gentamicin on a titanium surface, and to evaluate the in vitro drug release behaviour and antibacterial properties and biocompatibility of the controlled release system.

METHODS

Titanium (Ti) surface was coated with poly dopamine (PDA) substrate, and then polyethylene glycol (PEG) was attached to PDA. The composite drug microsphere controlled release layer formed by gentamicin (GEN) and cross-linked starch (CSt) were subsequently covered with poly lactic⁃co⁃glycolic acid (PLGA) as a barrier to construct a Ti-GEN-Cst-PLGA anti-infective drug controlled release system.

RESULTS

The hydrogel drug release system was successfully constructed. The results of in vitro anti-staphylococcus aureus (SAU) assay, anti-staphylococcus epidermidis (SEP) assay and anti-Escherichia coli (ECO) assay showed that Ti-GEN-Cst-PLGA could effectively inhibit the growth of three bacteria. Assay in the New Zealand rabbit found that Ti-GEN-Cst-PLGA could promote wound healing at the 3rd week after implantation, and the pathology assay found that the Ti-GEN-Cst-PLGA group had less inflammatory reactions and significant tissue proliferation at the endophyte contact surface.

CONCLUSION

Ti-GEN-Cst-PLGA can effectively inhibit the inflammatory response and promote wound healing, or may be a potential treatment for orthopaedic endophytes.

Novel dalbavancin-PLLA implant coating prevents hematogenous Staphylococcus aureus infection in a minimally invasive mouse tail vein model

Infective/bacterial endocarditis is a rare but life-threatening disease with a hospital mortality rate of 22.7% and a 1-year mortality rate of 40%. Therefore, continued research efforts to develop efficient anti-infective implant materials are of the utmost importance. Equally important is the development of test systems that allow the performance of new materials to be comprehensively evaluated. In this study, a novel antibacterial coating based on dalbavancin was tested in comparison to rifampicin/minocycline, and the suitability of a recently developed mouse tail vein model for testing the implant coatings was validated. Small polymeric stent grafts coated with a poly-L-lactic acid (PLLA) layer and incorporated antibiotics were colonized with Staphylococcus (S.) aureus before implantation into the tail vein of mice. The main assessment criteria were the hematogenous spread of the bacteria and the local tissue reaction to the contaminated implant. For this purpose, colony-forming units (CFU) in the blood, spleen and kidneys were determined. Tail cross sections were prepared for histological analysis, and plasma cytokine levels and expression values of inflammation-associated genes were examined. Both antibiotic coatings performed excellently, preventing the onset of infection. The present study expands the range of available methods for testing the anti-infectivity of cardiovascular implants, and the spectrum of agents for effective surface coating.

Effects of antibiotic treatment and phagocyte infiltration on development of Pseudomonas aeruginosa biofilm—Insights from the application of a novel PF hydrogel model in vitro and in vivo

Background and purpose

Bacterial biofilm infections are major health issues as the infections are highly tolerant to antibiotics and host immune defenses. Appropriate biofilm models are important to develop and improve to make progress in future biofilm research. Here, we investigated the ability of PF hydrogel material to facilitate the development and study of Pseudomonas aeruginosa biofilms in vitro and in vivo.

Methods

Wild-type P. aeruginosa PAO1 bacteria were embedded in PF hydrogel situated in vitro or in vivo, and the following aspects were investigated: 1) biofilm development; 2) host immune response and its effect on the bacteria; and 3) efficacy of antibiotic treatment.

Results

Microscopy demonstrated that P. aeruginosa developed typical biofilms inside the PF hydrogels in vitro and in mouse peritoneal cavities where the PF hydrogels were infiltrated excessively by polymorphonuclear leukocytes (PMNs). The bacteria remained at a level of ~10⁶ colony-forming unit (CFU)/hydrogel for 7 days, indicating that the PMNs could not eradicate the biofilm bacteria. β-Lactam or aminoglycoside mono treatment at 64× minimal inhibitory concentration (MIC) killed all bacteria in day 0 in vitro biofilms, but not in day 1 and older biofilms, even at a concentration of 256× MIC. Combination treatment with the antibiotics at 256× MIC completely killed the bacteria in day 1 in vitro biofilms, and combination treatment in most of the cases showed significantly better bactericidal effects than monotherapies. However, in the case of the established in vivo biofilms, the mono and combination antibiotic treatments did not efficiently kill the bacteria.

Conclusion

Our results indicate that the bacteria formed typical biofilms in PF hydrogel in vitro and in vivo and that the biofilm bacteria were tolerant against antibiotics and host immunity. The PF hydrogel biofilm model is simple and easy to fabricate and highly reproducible with various application possibilities. We conclude that the PF hydrogel biofilm model is a new platform that will facilitate progress in future biofilm investigations, as well as studies of the efficacy of new potential medicine against biofilm infections.

Implanting a Copper Ion into a TiO2 Nanorod Array for the Investigation on the Synergistic Antibacterial Mechanism between Mechanical Cracking and Chemical Damage

Titanium (Ti) and its alloys are extensively applied in dental and orthopedic implants due to their characteristics of good mechanical property and corrosion resistance. However, Ti and its alloys suffer from the absence of certain biological activity and antibacterial ability. Herein, we synthesized a titanium dioxide (TiO₂) nanorod array on the surface of a Ti plate, and the obtained TiO₂ nanorod array was further modified by Cu ions through ion implantation technology in an attempt to endow medical Ti with an antibacterial ability and maintain a normal biological function synchronously. The antibacterial ability of the TiO₂ nanorod array with the incorporation of Cu ions was vastly improved compared with those of the unmodified TiO₂ nanorod array and pure Ti. In particular, owing to the synergy between the chemical damage of the released Cu²⁺ to the cell and the mechanical cracking of the TiO₂ nanorod array, the antibacterial rate of the TiO₂ nanorod array modified by Cu ions against Escherichia coli or Staphylococcus aureus could reach 99%. In addition, no cytotoxicity was detected in such prepared coating during the CCK-8 assay. Moreover, the corrosion resistance of the sample was significantly better than that of pure Ti. Overall, we demonstrated that the application of ion implantation technology could open up a promising pathway to design and develop further antibacterial material for the biomedical domain.

Lipid Nanocarriers-Loaded Nanocomposite as a Suitable Platform to Release Antibacterial and Antioxidant Agents for Immediate Dental Implant Placement Restorative Treatment

Immediate implant placement is a single-stage restorative approach for missing teeth widely used to overcome the ridge remodeling process occurring after dental extractions. The success of this procedure relies on opportune osseointegration in the surrounding tissues. To support this process, a multifunctional nanocomposite, to be applied in the fresh post-extraction socket, was here designed, prepared, and characterized. This formulation consists of quercetin (QRC)-loaded nanostructured lipid carriers (NLCs) entrapped in a chitosan-based solid matrix containing ciprofloxacin (CPX). QRC-NLCs were prepared by homogenization followed by high-frequency sonication, and thereafter this dispersion was trapped in a chitosan-based CPX-loaded gel, obtaining the nanocomposite powder (BioQ-CPX) by lyophilization. BioQ-CPX displayed desirable properties such as high porosity (94.1 ± 0.5%), drug amounts (2.1% QRC and 3.5% CPX). and low swelling index (100%). Moreover, the mechanism of drug release from BioQ-CPX and their ability to be accumulated in the target tissue were in vitro and ex vivo elucidated, also by applying mathematical models. When trapped into the nanocomposite, QRC stressed under UV light exposure (50 W) was shown to maintain its antioxidant power, and CPX and QRC under natural light were stable over nine months. Finally, both the measured antioxidant power and the antimicrobial and antibiofilm properties on Staphylococcus aureus demonstrated that BioQ-CPX could be a promising platform to support the single-stage dental restorative treatment.

Novel Chitosan-Silica Hybrid Hydrogels for Cell Encapsulation and Drug Delivery

Hydrogels constructed from naturally derived polymers provide an aqueous environment that encourages cell growth, however, mechanical properties are poor and degradation can be difficult to predict. Whilst, synthetic hydrogels exhibit some improved mechanical properties, these materials lack biochemical cues for cells growing and have limited biodegradation. To produce hydrogels that support 3D cell cultures to form tissue mimics, materials must exhibit appropriate biological and mechanical properties. In this study, novel organic-inorganic hybrid hydrogels based on chitosan and silica were prepared using the sol-gel technique. The chemical, physical and biological properties of the hydrogels were assessed. Statistical analysis was performed using One-Way ANOVAs and independent-sample t-tests. Fourier transform infrared spectroscopy showed characteristic absorption bands including amide II, Si-O and Si-O-Si confirming formation of hybrid networks. Oscillatory rheometry was used to characterise the sol to gel transition and viscoelastic behaviour of hydrogels. Furthermore, in vitro degradation revealed both chitosan and silica were released over 21 days. The hydrogels exhibited high loading efficiency as total protein loading was released in a week. There were significant differences between TC₂G and C₂G at all-time points (p < 0.05). The viability of osteoblasts seeded on, and encapsulated within, the hydrogels was >70% over 168 h culture and antimicrobial activity was demonstrated against Pseudomonas aeruginosa and Enterococcus faecalis. The hydrogels developed here offer alternatives for biopolymer hydrogels for biomedical use, including for application in drug/cell delivery and for bone tissue engineering.

Impact of High-Dose Anti-Infective Agents on the Osteogenic Response of Mesenchymal Stem Cells

Treatment of infected nonunions and severe bone infections is a huge challenge in modern orthopedics. Their treatment routinely includes the use of anti-infective agents. Although frequently used, little is known about their impact on the osteogenesis of mesenchymal stem cells. In a high- and low-dose set-up, this study evaluates the effects of the antibiotics Gentamicin and Vancomycin as well as the antifungal agent Voriconazole on the ability of mesenchymal stem cells to differentiate into osteoblast-like cells and synthesize hydroxyapatite in a monolayer cell culture. The osteogenic activity was assessed by measuring calcium and phosphate concentrations as well as alkaline phosphatase activity and osteocalcin concentration in the cell culture medium supernatant. The amount of hydroxyapatite was measured directly by radioactive ^99mTechnetium-HDP labeling. Regarding the osteogenic markers, it could be concluded that the osteogenesis was successful within the groups treated with osteogenic cell culture media. The results revealed that all anti-infective agents have a cytotoxic effect on mesenchymal stem cells, especially in higher concentrations, whereas the measured absolute amount of hydroxyapatite was independent of the anti-infective agent used. Normed to the number of cells it can therefore be concluded that the above-mentioned anti-infective agents actually have a positive effect on osteogenesis while high-dose Gentamycin, in particular, is apparently capable of boosting the deposition of minerals.

Septic arthritis in the end-stage renal disease population

Septic arthritis is important to consider in any patient who presents with joint pain because it is a medical emergency with an 11% fatality rate. Diagnosis and treatment may improve prognosis; however, many patients do not regain full joint function. In patients with end-stage renal disease (ESRD), immune dysfunction due to uremia and chronic vascular access leads to increased risk of infection. We examined the incidence, risk factors and sequelae of septic arthritis in a cohort of hemodialysis patients. The US Renal Data System was queried for diagnoses of septic arthritis and selected sequelae using International Statistical Classification of Diseases and Related Health Problems-9 and Current Procedural Terminology-4 codes in patients who initiated hemodialysis between 2005 and 2010. Multivariable logistic regression was used to determine potential risk factors for septic arthritis and its sequelae. 7009 cases of septic arthritis were identified, an incidence of 514.8 per 100,000 persons per year. Of these patients, 2179 were diagnosed with a documented organism within 30 days prior to or 14 days after the septic arthritis diagnosis, with methicillin-resistant Staphylococcus aureus infections (57.4%) being the most common. Significant risk factors for septic arthritis included history of joint disease, immune compromise (diabetes, HIV, cirrhosis), bacteremia and urinary tract infection. One of the four sequelae examined (joint replacement, amputation, osteomyelitis, Clostridioides difficile infection) occurred in 25% of septic arthritis cases. The high incidence of septic arthritis and the potential for serious sequelae in patients with ESRD suggest that physicians treating individuals with ESRD and joint pain/inflammation should maintain a high clinical suspicion for septic arthritis.

Synovial fluid pH sensor for early detection of prosthetic hip infections

We describe an implantable sensor developed to measure synovial fluid pH for noninvasive early detection and monitoring of hip infections using standard-of-care plain radiography. The sensor was made of a pH responsive polyacrylic acid-based hydrogel, which expands at high pH and contracts at low pH. A radiodense tantalum bead and a tungsten wire were embedded in the two ends of the hydrogel in order to monitor the change in length of the hydrogel sensor in response to pH via plain radiography. The effective pKa of the hydrogel-based pH sensor was 5.6 with a sensitivity of 3 mm/pH unit between pH 4 and 8. The sensor showed a linear response and reversibility in the physiologically relevant pH range of pH 6.5 and 7.5 in both buffer and bovine synovial fluid solutions with a 30-minute time constant. The sensor was attached to an explanted prosthetic hip and the pH response determined from the X-ray images by measuring the length between the tantalum bead and the radiopaque wire. Therefore, the developed sensor would enable noninvasive detection and studying of implant hip infection using plain radiography.

Titanium implant coating based on dopamine-functionalized sulphated hyaluronic acid: in vivo assessment of biocompatibility and antibacterial efficacy

The number of total knee and/or hip replacements are expected to exceed 5 million a year by 2030; the incidence of biofilm-associated complications can vary from 1% in primary implants to 5.6% in case of revision. The purpose of this study was to test the ability of sHA-DA, a partially sulphated hyaluronic acid (sHA) functionalized with a dopamine (DA) moiety, to prevent acute bacterial growth in an in vivo model of an intra-operatively highly contaminated implant. Previously, in vitro studies showed that the DA moiety guarantees good performance as binding agent for titanium surface adhesion, while the negatively charged sHA has both a high efficiency in electrostatic binding of positively charged antibiotics, and bone regenerative effects. The in vitro testing also highlighted the effectiveness of the sHA-DA system in inhibiting bacterial spreading through a sustained release of the antibiotic payload from the implant coating. In this study the chemical stability of the sHA-DA to β-ray sterilization was demonstrated, based on evaluation by NMR, SEC-TDA Omnisec and HPLC-MS analysis, thus supporting the approach of terminal sterilization of the coated implant with no loss of efficacy. Furthermore, an in vivo study in rabbits was performed according to UNI EN ISO 10993-6 to assess the histocompatibility of titanium nails pre-coated with sHA-DA. The implants, placed in the femoral medullary cavity and harvested after 12 weeks, proved to be histocompatible and to allow bone growth in adhesion to the metal surface. Finally, an in vivo model of bacterial contamination was set up by injecting 1 mL of bacterial suspension containing 10⁴ or 10⁶ CFU of methicillin-resistant Staphylococcus aureus (MRSA) into the femoral medullary cavity of 30 rabbits. Titanium nails either uncoated or pre-coated with sHA-DA and loaded directly by the surgeon with 5% vancomycin were implanted in the surgical site. After 1 week, only the animals treated with pre-coated nails did not show the presence of systemic or local bacterial infection, as confirmed by microbiology and histology (Smeltzer score). Further insights into the animal model setup are crucial, however the results obtained suggest that the system can be effective in preventing the onset of the bacterial infective process.

Hydroxyapatite Obtained via the Wet Precipitation Method and PVP/PVA Matrix as Components of Polymer-Ceramic Composites for Biomedical Applications

The aspect of drug delivery is significant in many biomedical subareas including tissue engineering. Many studies are being performed to develop composites with application potential for bone tissue regeneration which at the same provide adequate conditions for osteointegration and deliver the active substance conducive to the healing process. Hydroxyapatite shows a great potential in this field due to its osteoinductive and osteoconductive properties. In the paper, hydroxyapatite synthesis via the wet precipitation method and its further use as a ceramic phase of polymer-ceramic composites based on PVP/PVA have been presented. Firstly, the sedimentation rate of hydroxyapatite in PVP solutions has been determined, which allowed us to select a 15% PVP solution (sedimentation rate was 0.0292 mm/min) as adequate for preparation of homogenous reaction mixture treated subsequently with UV radiation. Both FT-IR spectroscopy and EDS analysis allowed us to confirm the presence of both polymer and ceramic phase in composites. Materials containing hydroxyapatite showed corrugated and well-developed surface. Composites exhibited swelling properties (hydroxyapatite reduced this property by 25%) in simulated physiological fluids, which make them useful in drug delivery (swelling proceeds parallel to the drug release). The short synthesis time, possibility of preparation of composites with desired shapes and sizes and determined physicochemical properties make the composites very promising for biomedical purposes.

Antimicrobial Polymeric Composites with Embedded Nanotextured Magnesium Oxide

Nanotextured magnesium oxide (MgO) can exhibit both antibacterial and tissue regeneration activity, which makes it very useful for implant protection. To successfully combine these two properties, MgO needs to be processed within an appropriate carrier system that can keep MgO surface available for interactions with cells, slow down the conversion of MgO to the less active hydroxide and control MgO solubility. Here we present new composites with nanotextured MgO microrods embedded in different biodegradable polymer matrixes: poly-lactide-co-glycolide (PLGA), poly-lactide (PLA) and polycaprolactone (PCL). Relative to their hydrophilicity, polarity and degradability, the matrices were able to affect and control the structural and functional properties of the resulting composites in different manners. We found PLGA matrix the most effective in performing this task. The application of the nanotextured 1D morphology and the appropriate balancing of MgO/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus (multidrug resistant-MRSA) and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells.

Outcomes and Complications With Treatment of Open Tibial Plafond Fractures With Circular External Fixator

BACKGROUND

Open tibial plafond fractures (Orthopaedic Trauma Association and AO Foundation [OTA/AO] 43) are associated with severe complications, including deep infection (closed fractures, 20%; open fractures, 30%), amputation (3%-14%), and nonunion (up to 25%). Circular external fixators (CEFs) can minimize soft tissue injury. This study aimed to report the rate of union and occurrence of severe complications in patients with open tibial plafond fractures treated with CEFs.

METHODS

A retrospective review of case series was conducted at 3 level I trauma centers. The study included patients older than 18 years with open tibial plafond fractures treated with CEFs. The reported outcomes included union rate, deep infection, operative complications, and limb alignment. The radiographic measurements of anatomic alignment were obtained. Fifty-two patients were included in the study.

RESULTS

The primary union rate was 79%. No deep infection occurred in the majority (92%) of patients. No patient required amputation of the affected limb or free flap coverage.

CONCLUSION

Definitive fixation of open tibial plafond fractures with CEFs avoided severe soft tissue complications but resulted in variation in final radiographic alignment.

LEVEL OF EVIDENCE

Level IV, case series.

Anti-Periprosthetic Infection Strategies: From Implant Surface Topographical Engineering to Smart Drug-Releasing Coatings

Despite advanced implant sterilization and aseptic surgical techniques, periprosthetic bacterial infection remains a major challenge for orthopedic and dental implants. Bacterial colonization/biofilm formation around implants and their invasion into the dense skeletal tissue matrices are difficult to treat and could lead to implant failure and osteomyelitis. These complications require major revision surgeries and extended antibiotic therapies that are associated with high treatment cost, morbidity, and even mortality. Effective preventative measures mitigating risks for implant-related infections are thus in dire need. This review focuses on recent developments of anti-periprosthetic infection strategies aimed at either reducing bacterial adhesion, colonization, and biofilm formation or killing bacteria directly in contact with and/or in the vicinity of implants. These goals are accomplished through antifouling, quorum-sensing interfering, or bactericidal implant surface topographical engineering or surface coatings through chemical modifications. Surface topographical engineering of lotus leaf mimicking super-hydrophobic antifouling features and cicada wing-mimicking, bacterium-piercing nanopillars are both presented. Conventional physical coating/passive release of bactericidal agents is contrasted with their covalent tethering to implant surfaces through either stable linkages or linkages labile to bacterial enzyme cleavage or environmental perturbations. Pros and cons of these emerging anti-periprosthetic infection approaches are discussed in terms of their safety, efficacy, and translational potentials.

3D Bioprinted Bacteriostatic Hyperelastic Bone Scaffold for Damage-Specific Bone Regeneration

Current strategies for regeneration of large bone fractures yield limited clinical success mainly due to poor integration and healing. Multidisciplinary approaches in design and development of functional tissue engineered scaffolds are required to overcome these translational challenges. Here, a new generation of hyperelastic bone (HB) implants, loaded with superparamagnetic iron oxide nanoparticles (SPIONs), are 3D bioprinted and their regenerative effect on large non-healing bone fractures is studied. Scaffolds are bioprinted with the geometry that closely correspond to that of the bone defect, using an osteoconductive, highly elastic, surgically friendly bioink mainly composed of hydroxyapatite. Incorporation of SPIONs into HB bioink results in enhanced bacteriostatic properties of bone grafts while exhibiting no cytotoxicity. In vitro culture of mouse embryonic cells and human osteoblast-like cells remain viable and functional up to 14 days on printed HB scaffolds. Implantation of damage-specific bioprinted constructs into a rat model of femoral bone defect demonstrates significant regenerative effect over the 2-week time course. While no infection, immune rejection, or fibrotic encapsulation is observed, HB grafts show rapid integration with host tissue, ossification, and growth of new bone. These results suggest a great translational potential for 3D bioprinted HB scaffolds, laden with functional nanoparticles, for hard tissue engineering applications.

Silver Nanoparticles Attenuate the Antimicrobial Activity of the Innate Immune System by Inhibiting Neutrophil-Mediated Phagocytosis and Reactive Oxygen Species Production

PURPOSE

Despite the extensive development of antibacterial biomaterials, there are few reports on the effects of materials on the antibacterial ability of the immune system, and in particular of neutrophils. In this study, we observe differences between the in vivo and in vitro anti-infective efficacies of silver nanoparticles (AgNPs). The present study was designed to further explore the mechanism for this inconsistency using ex vivo models and in vitro experiments.

METHODS

AgNPs were synthesized using the polyol process and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The antibacterial ability of AgNPs and neutrophils was tested by the spread-plate method. The infected air pouch model was prepared to detect the antimicrobial ability of AgNPs in vivo. Furthermore, blood-AgNPs-bacteria co-culture model and reactive oxygen species (ROS) measurement were used to evaluate the effect of AgNPs to neutrophil-mediated phagocytosis and ROS production.

RESULTS

The antibacterial experiments in vitro showed that AgNPs had superior antibacterial properties in cell compatible concentration. While, AgNPs had no significant antibacterial effect in vivo, and pathological section in AgNPs group indicated less neutrophil infiltration in inflammatory site than S. aureus group. Furthermore, AgNPs were found to reduce the phagocytosis of neutrophils and inhibit their ability to produce ROS and superoxide during ex vivo and in vitro experiments.

CONCLUSION

This study selects AgNPs as the representative of inorganic nano-biomaterials and reveals the phenomenon and the mechanism underlying the significant AgNPs-induced inhibition of the antibacterial ability of neutrophils, and may have a certain enlightening effect on the development of biomaterials in the future. In the fabrication of antibacterial biomaterials, however, attention should be paid to both cell and immune system safety to make the antibacterial properties of the biomaterials and innate immune system complement each other and jointly promote the host's ability to resist the invasion of pathogenic microorganisms.

Optimal Design of Paired Built Environment Interventions for Control of MDROs in Acute Care and Community Hospitals

OBJECTIVES

Our goal was to optimize infection control of paired environmental control interventions within hospitals to reduce methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), and vancomycin-resistant Enterococci (VRE).

BACKGROUND

The most widely used infection control interventions are deployment of handwashing (HW) stations, control of relative humidity (RH), and negative pressure (NP) treatment rooms. Direct costs of multidrug-resistant organism (MDRO) infections are typically not included in the design of such interventions.

METHODS

We examined the effectiveness of pairing HW with RH and HW with NP. We used the following three data sets: A meta-analysis of progression rates from uncolonized to colonized to infected, 6 years of MDRO treatment costs from 400 hospitals, and 8 years of MDRO incidence rates at nine army hospitals. We used these data as inputs into an Infection De-Escalation Model with varying budgets to obtain optimal intervention designs. We then computed the infection and prevention rates and cost savings resulting from these designs.

RESULTS

The average direct cost of an MDRO infection was $3,289, $1,535, and $1,067 for MRSA, CRE, and VRE. The mean annual incidence rates per facility were 0.39%, 0.034%, and 0.011% for MRSA, CRE, and VRE. After applying the cost-minimizing intervention pair to each scenario, the percentage reductions in infections (and annual direct cost savings) in large, community, and small acute care hospitals were 69% ($1.5 million), 73% ($631K), 60% ($118K) for MRSA, 52% ($460.5K), 58% ($203K), 50% ($37K) for CRE, and 0%, 0%, and 50% ($12.8K) for VRE.

CONCLUSION

The application of this Infection De-Escalation Model can guide cost-effective decision making in hospital built environment design to improve control of MDRO infections.

Bacteriocin-a potential antimicrobial peptide towards disrupting and preventing biofilm formation in the clinical and environmental locales

Biofilm, a consortium of microbial cells, protected by extracellular polymeric matrix, is considered a global challenge due to the inherent antibiotic resistance conferred by its lifestyle. Besides, it poses environmental threats causing huge damage in food industries, fisheries, refineries, water systems, pharmaceutical industries, medical industries, etc. Living in a community of microbial populations is most critical in the clinical field, making it responsible for about 80% of severe and chronic microbial diseases. The necessity to find an alternative approach is the need of the hour to solve these crises. So far, many approaches have been attempted to disrupt the initial stage of biofilm formation, including adherence and maturation. Bacteriocins are a group of antimicrobial peptides, produced by bacteria having the potential to disrupt biofilm either by itself or in combination with other drugs than antibiotic counterparts. A clear understanding on mechanisms of bacterial biofilm formation, progression, and resistance will surely lead to the development of innovative, effective biofilm control strategies in pharmaceutical, health care industries and environmental locales.

Bioinspired antibacterial surface for orthopedic and dental implants

Bacterial infections still present a significant concern in orthopedic and dental implant failure. Previous investigations have focused on modifying the surface texture, roughness, or coating implants with antibiotics to provide enhanced anti-bacterial properties. However, they have demonstrated limited success. In this study, we attempted to engineer the titanium (Ti) alloy surface biomimetically at the nano level using alkaline hydrothermal treatment (AHT) inspired by cicada's wing structure. Two modified surfaces of Ti plates were developed using 4 and 8-hr AHT at 230°C. We found that the control plates showed a relatively smooth surface, with little artifacts on the surface. In contrast, 4-hr AHT and 8-hr AHT plates showed nano-spikes of heights around 250-350 and 100-1,250 nm, respectively, that were distributed randomly all over the surface. We found a statistically significant (p < 0.05) number of non-viable cells for both S. aureus and P. aeruginosa bacterial strains when incubated for 1 hr in a dynamic environment when compared with the control group. The 8-hr AHT groups killed 38.97% more S. aureus in static culture and 11.27% in a dynamic environment than the 4-hr AHT. Overall, the findings indicate that the nanostructures generated on titanium by the AHT showed significant bactericidal properties. We, therefore, recommend conducting alkaline hydrothermal treatment on the surfaces for future orthopedic and dental metallic implants.

Borate and Silicate Bioactive Glass Coatings Prepared by Nanosecond Pulsed Laser Deposition

Silicate (13-93) and borate (13-93-B3) bioactive glass coatings were successfully deposited on titanium using the nanosecond Pulsed Laser Deposition technique. The coatings’ microstructural characteristics, compositions and morphologies were examined by a number of physico-chemical techniques. The deposited coatings retain the same functional groups of the targets, are a few microns thick, amorphous, compact and crack free. Their surface is characterized by the presence of micrometric and nanometric particles. The surface topography, investigated by Atomic Force Microscopy, is characterized by spherical or ellipsoidal particles of the 0.2–3 μm size range for the 13-93 silicate bioactive glass film and of the 0.1–1 µm range for the 13-93-B3 borate bioactive glass coating. Equine adipose tissue-derived mesenchymal stem cells (ADMSCs) were applied for biological tests and the osteogenic differentiation activity of cells on the deposited coatings was studied after ADMSCs growth in osteogenic medium and staining with Alizarin Red. Cytocompatibility and osteogenic differentiation tests have shown that thin films retain the biocompatibility properties of the target silicate and borate glass, respectively. On the other hand, no antibacterial activity of the borate glass films was observed, suggesting that ion doping is advisable to inhibit bacterial growth on the surface of borate glass thin films.

Mechanical behavior of in-situ alloyed Ti6Al4V(ELI)-3 at.% Cu lattice structures manufactured by laser powder bed fusion and designed for implant applications

In the present study, cellular lattice structures for implant applications are reported for the first-time incorporating copper directly by in-situ alloying in the laser powder bed fusion process. The aim to incorporate 3 at.% Cu into Ti6Al4V(ELI) is selected for improved antibacterial properties while maintaining appropriate mechanical properties. Previously, topologically optimized Ti6Al4V(ELI) lattice structures were successfully designed, manufactured and studied for implant applications. The development of a new alloy produced by in-situ alloying of elemental powder mixture of Ti6Al4V(ELI) and pure Cu powders was used here for the production of identical lattice structures with improved antibacterial properties. One of the same as-designed CAD models was used for the manufacturing of these lattices compared to previous work on pure Ti6Al4V(ELI) lattices, making direct comparison of mechanical properties possible. Similar manufacturability highlights the applicability of this alloying technique to other lattice designs. Microstructural characterization was performed by optical and electron microscopies, as well as microCT. Mechanical characterization was performed by means of compression tests and hardness measurements. Results showed that in-situ alloying with copper leads to the formation of localized Cu-rich regions, refinement of martensitic phase and the formation of CuTi₂ intermetallic precipitates, which increased the hardness and strength of the material. Deviations in wall thickness between the as-designed and as-manufactured lattices led to anisotropy of the mechanical properties of the lattices. Higher compressive strength values were obtained when thicker walls were oriented along the loading direction. Nevertheless, alloying with Cu had a higher impact on the compressive strength of lattice structure than the wall thickness deviations. The direct in-situ alloying of copper in Ti6Al4V(ELI) is a promising route for direct manufacturing of antibacterial implants.

Optimization of anti-wear and anti-bacterial properties of beta TiNb alloy via controlling duty cycle in open-air laser nitriding

A multifunctional beta TiNb surface, featuring wear-resistant and antibacterial properties, was successfully created by means of open-air fibre laser nitriding. Beta TiNb alloy was selected in this study as it has low Young's modulus, is highly biocompatible, and thus can be a promising prosthetic joint material. It is, however, necessary to overcome intrinsically weak mechanical properties and poor wear resistance of beta TiNb in order to cover the range of applications to load-bearing and/or shearing parts. To this end, open-air laser nitriding technique was employed. A control of single processing parameter, namely duty cycle (between 5% and 100%), led to substantially different structural and functional properties of the processed beta TiNb surfaces as analyzed by an array of analytical tools. The TiNb samples nitrided at the DC condition of 60% showed a most enhanced performance in terms of improving surface hardness, anti-friction, anti-wear and anti-bacterial properties in comparison with other conditions. These findings are expected to be highly important and useful when TiNb alloys are considered as materials for hip/knee articular joint implants.

Surface-grafted zwitterionic polymers improve the efficacy of a single antibiotic injection in suppressing S. aureus periprosthetic infections

Implant-associated bacterial infections are difficult to treat due to the tendency of biofilm formation on implant surfaces, which protects embedded pathogens from host defense and impedes antibiotic penetration, rendering systemic antibiotic injections ineffective. Here, we test the hypothesis that implant coatings that reduce bacterial colonization would make planktonic bacteria within the periprosthetic environment more susceptible to conventional systemic antibiotic treatment. We covalently grafted zwitterionic polymer brushes poly(sulfobetaine methacryate) from Ti6Al4V surface to increase the substrate surface hydrophilicity and reduce staphylococcus aureus (S. aureus) adhesion. Using a mouse femoral intramedullary (IM) canal infection model, we showed that the anti-fouling coating applied to Ti6Al4V IM implants, when combined with a single vancomycin systemic injection, significantly suppressed both bacterial colonization on implant surfaces and the periprosthetic infections, outperforming either treatment alone. This work supports the hypothesis that grafting anti-fouling polymers to implant surfaces improves the efficacy of systemic antibiotic injections to combat periprosthetic infections.

Dual-function membranes based on alginate/methyl cellulose composite for control drug release and proliferation enhancement of fibroblast cells

Membranes based on natural polymers are highly promising therapies for skin damaged sites as they can mimic its biological microstructure to support the fibroblasts cells survival and proliferation. In addition, these membranes could be loaded with active molecules that help in skin regeneration and eliminate the potential bacterial infection. This research aims to formulate novel medicated membranes for controlled release and cytocompatibility elevation of fibroblast cells for engineering of soft tissue. Pre-formulation researches have been conducted for membranes of sodium alginate (Alg)/methyl cellulose (MC) that used loaded with undoped, Bi doped and Bi, Cu co-doped SrTiO₃ using solvent casting technique. In addition, another group of these membranes were loaded with DOXycycline antibiotic (DOX) as model drug as well as for eliminating the potential bacterial infections. The prepared membranes were evaluated by XRD, SEM-EDX, FTIR, Zetasizer, and swelling behaviour was also tested. Profiles of the released drug were determined using phosphate-buffered saline (PBS) (pH 7.4) at 37 °C for 30 days. The investigation of the cytocompatibility and proliferation of fibroblast cells with the prepared membranes were conducted. The XRD, FTIR and SEM data recognised the possible interaction that takes place among Alg and MC, through presence of hydrogen bonds. Existence of the nano-particles within the membrane polymer matrix enhanced the membrane stability and enhanced the drug release rate (from 20 to 45%). Medication release mechanism elucidated that DOX was released from all the fabricated membranes through the relaxation of polymer matrix that takes place after swelling. The filler type and/or dopant type possess no remarkable influence on the cytotoxicity of the membranes against the investigated cells when compared to their individual influence on the same cells. Cells attachments results have revealed an impressive effect for DOX-loaded membranes on the cells affinity and growth. These membranes are recommended for treatments of skin infections.

High Rates of Aseptic Loosening After Revision Total Knee Arthroplasty for Periprosthetic Joint Infection

With increasing life expectancy, the demand for knee replacement is continuously rising. Despite the use of antibiotic prophylaxis and improved aseptic surgical techniques, periprosthetic joint infection (PJI) still occurs in 1% to 5% of patients after primary arthroplasty. An open question is the influence of PJI and resulting surgical procedures on the occurrence of long-term complications such as aseptic loosening. Patients needing multiple revision surgeries are especially at risk for decreases in bone mass and damage to the medullary cavity. Thus, we theorized that prior surgeries on the affected knee increase the risk of aseptic loosening in patients with PJI.

Bioengineered Nisin Derivative M17Q Has Enhanced Activity against Staphylococcus epidermidis

Staphylococcus epidermidis is frequently implicated in medical device-related infections. As a result of this, novel approaches for control of this opportunistic pathogen are required. We examined the ability of the natural peptide nisin A, produced by Lactococcus lactis, to inhibit S. epidermidis. In addition, a bank of 29 rationally selected bioengineered L. lactis strains were examined with the aim of identifying a nisin derivative with enhanced antimicrobial activity. Agar-based deferred antagonism assays revealed that wild type nisin A inhibited all 18 S. epidermidis strains tested. Larger zones of inhibition than those obtained from the nisin A producing L. lactis strain were observed for each derivative producer against at least one S. epidermidis strain tested. Six derivative producing strains, (VGA, VGT, SGK, M21A, M17Q, AAA), gave larger zones against all 18 strains compared to the wildtype producing strain. The enhanced bioactivity of M17Q was confirmed using well diffusion, minimum inhibitory concentration (MIC) and a broth-based survival assays. Biofilm assays were performed with plastic microtiter plates and medical device substrates (stainless-steel coupons and three catheter materials). The presence of nisin A significantly reduce the amount of biofilm formed on all surfaces. M17Q was significantly better at reducing biofilm production than nisin A on plastic and stainless-steel. Finally, M17Q was significantly better than nisin A at reducing bacterial numbers in a simulated wound fluid. The findings of this study suggest that nisin and bioengineered derivatives warrant further investigation as potential strategies for the control of S. epidermidis.

Effect of Ageing on the Structure and Properties of Model Liquid-Infused Surfaces

Liquid-infused surfaces (LISs) exhibit unique properties that make them ideal candidates for a wide range of applications, from antifouling and anti-icing coatings to self-healing surfaces and controlled wetting. However, when exposed to realistic environmental conditions, LISs tend to age and progressively lose their desirable properties, potentially compromising their application. The associated ageing mechanisms are still poorly understood, and results reflecting real-life applications are scarce. Here, we track the ageing of a model LIS composed of glass surfaces functionalized with hydrophobic nanoparticles and infused with silicone oil. The LISs are fully submerged in aqueous solutions and exposed to acoustic pressure waves for set time intervals. The ageing is monitored by periodic measurements of the LIS's wetting properties. We also track the changes to the LIS's nanoscale structure. We find that the LISs rapidly lose their slippery properties because of a combination of oil loss, smoothing of the nanoporous functional layer, and substrate degradation when directly exposed to the solution. The oil loss is consistent with water microdroplets entering the oil layer and displacing oil away from the surface. These mechanisms are general and could play a role in the ageing of most LISs.

The Effect of Vancomycin on the Viability and Osteogenic Potential of Bone-Derived Mesenchymal Stem Cells

Traditionally, methicillin-resistant Staphylococcus aureus (MRSA) is treated with vancomycin, administrated intravenously or applied directly onto infected tissue. The effect of direct (as opposed to systemic) vancomycin treatment on bone formation and remodelling is largely unknown. The minimal inhibitory concentration (MIC) of vancomycin was determined by adding 200 μL of different concentrations (1-20 μg/mL) to actively growing cultures of S. aureus Xen 31 (methicillin-resistant) and S. aureus Xen 36 (methicillin-sensitive), respectively, and recording changes in optical density over 24 h. Bone marrow-derived and proximal femur-derived mesenchymal stem cells (bmMSCs and pfMSCs) from rat femora were exposed to 1 × MIC (5 μg/mL) and 4 × MIC (20 μg/mL) of vancomycin for 7 days. Cell viability was determined by staining with crystal violet and MTT (3-(4,5- di methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), respectively, and osteogenic differentiation by staining with Alizarin Red S. Vancomycin had no effect on the viability of bmMSCs and pfMSCs, even at high levels (20 μg/mL). The osteogenic differentiation of pfMSCs was partially inhibited, while osteogenesis in bmMSCs was not severely affected. The direct application of vancomycin to infected bone tissue, even at excessive levels, may preserve the viability of resident MSC populations.

Is dental prophylaxis required following spinal fusion?-a systematic review and call for evidence

BACKGROUND

Controversy exists regarding the need for antimicrobial prophylaxis prior to dental procedures following spinal fusion. In this review, we attempt to synthesize a comprehensive summary of the published literature to provide recommendations on the use of antimicrobial prophylaxis before dental procedures in patients with a history of spinal fusion.

METHODS

We searched PubMed, Web of Science, Cochrane Library, and EMBASE databases from inception to February 2018. Eligible studies included patients with a history of spinal fusion treated with or without antimicrobial prophylaxis in preparation for dental procedures. Two reviewers independently assessed the eligibility of potential studies and extracted data. Outcomes of interest were the indications and efficacy of antimicrobial prophylaxis to protect against infection of spinal prostheses with dental origin.

RESULTS

A total of 1,909 articles were initially screened. After inclusion and exclusion criteria were applied, one study was found specifically relating to dental prophylaxis and spine surgery. The survey, as well as objective studies and professional organization guidelines on dental prophylaxis in patients with total hip and knee replacements, were reviewed to add context to the controversy.

CONCLUSIONS

There is a significant paucity of literature regarding dental prophylaxis in spine surgery patients. Although there has been a recent movement away from recommending antimicrobial prophylaxis before dental work in patients with other forms of orthopaedic prostheses, the gap in the literature addressing spine patients represents an important question that requires more targeted and specific research.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

Application of Non-Thermal Plasma on Biofilm: A Review

The formation of bacterial biofilm on implanted devices or damaged tissues leads to biomaterial-associated infections often resulting in life-threatening diseases and implant failure. It is a challenging process to eradicate biofilms as they are resistant to antimicrobial treatments. Conventional techniques, such as high heat and chemicals exposure, may not be suitable for biofilm removal in nosocomial settings. These techniques create surface degradation on the treated materials and lead to environmental pollution due to the use of toxic chemicals. A novel technique known as non-thermal plasma has a great potential to decontaminate or sterilize those nosocomial biofilms. This article aims to provide readers with an extensive review of non-thermal plasma and biofilms to facilitate further investigations. A brief introduction summarizes the problem caused by biofilms in hospital settings with current techniques used for biofilm inactivation followed by the literature review strategy. The remainder of the review discusses plasma and its generation, the role played by plasma reactive species, various factors affecting the antimicrobial efficacy of non-thermal plasma and summarizes many studies published in the field.

Polymeric Composites with Silver (I) Cyanoximates Inhibit Biofilm Formation of Gram-Positive and Gram-Negative Bacteria

Biofilms are surface-associated microbial communities known for their increased resistance to antimicrobials and host factors. This resistance introduces a critical clinical challenge, particularly in cases associated with implants increasing the predisposition for bacterial infections. Preventing such infections requires the development of novel antimicrobials or compounds that enhance bactericidal effect of currently available antibiotics. We have synthesized and characterized twelve novel silver(I) cyanoximates designated as Ag(ACO), Ag(BCO), Ag(CCO), Ag(ECO), Ag(PiCO), Ag(PICO) (yellow and red polymorphs), Ag(BIHCO), Ag(BIMCO), Ag(BOCO), Ag(BTCO), Ag(MCO) and Ag(PiPCO). The compounds exhibit a remarkable resistance to high intensity visible light, UV radiation and heat and have poor solubility in water. All these compounds can be well incorporated into the light-curable acrylate polymeric composites that are currently used as dental fillers or adhesives of indwelling medical devices. A range of dry weight % from 0.5 to 5.0 of the compounds was tested in this study. To study the potential of these compounds in preventing planktonic and biofilm growth of bacteria, we selected two human pathogens (Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus) and Gram-positive environmental isolate Bacillus aryabhattai. Both planktonic and biofilm growth was abolished completely in the presence of 0.5% to 5% of the compounds. The most efficient inhibition was shown by Ag(PiCO), Ag(BIHCO) and Ag(BTCO). The inhibition of biofilm growth by Ag(PiCO)-yellow was confirmed by scanning electron microscopy (SEM). Application of Ag(BTCO) and Ag(PiCO)-red in combination with tobramycin, the antibiotic commonly used to treat P. aeruginosa infections, showed a significant synergistic effect. Finally, the inhibitory effect lasted for at least 120 h in P. aeruginosa and 36 h in S. aureus and B. aryabhattai. Overall, several silver(I) cyanoximates complexes efficiently prevent biofilm development of both Gram-negative and Gram-positive bacteria and present a particularly significant potential for applications against P. aeruginosa infections.

Preparation and Evaluation of Antimicrobial Hyperbranched Emulsifiers for Waterborne Coatings

Nosocomial infections are a major problem in medical health care. To solve this problem, a series of antimicrobial waterborne paints were prepared by using antimicrobial hyperbranched (HB) emulsifiers. The HB-emulsifiers were prepared by polymerizing AB₂ monomers obtained in a one-step reaction of bis(hexamethylene)triamine and carbonyl biscaprolactam. The blocked isocyanate end groups (B groups) of the HB-polymer were utilized to introduce tertiary amino groups through the reaction with compounds comprising either a hydroxyl or a primary amino group and a tertiary amino group. Quaternization of the tertiary amines with 6 different alkyl bromides resulted in 12 amphiphilic cationic species. The 12 emulsifiers showed the successful inhibition and killing of 8 bacterial and 2 fungal strains. The killing efficacy increased with increasing alkyl chain length. The octyl-functionalized compound was chosen for suspension polymerizations because of the good compromise between killing and emulsifying properties. With this emulsifier, aqueous poly(methacrylate) suspensions were prepared, which were stable and had excellent killing properties.

Cosmetic reconstruction in breast cancer patients: Opportunities for nanocomposite materials

The most common malignancy in women, breast cancer remains a major medical challenge that affects the life of thousands of patients every year. With recognized benefits to body image and self-esteem, the use of synthetic mammary implants for elective cosmetic augmentation and post-mastectomy reconstruction continues to increase. Higher breast implant use leads to an increased occurrence of implant-related complications associated with implant leakage and rupture, capsular contracture, necrosis and infections, which include delayed healing, pain, poor aesthetic outcomes and the need for revision surgeries. Along with the health status of the implant recipient and the skill of the surgeon, the properties of the implant determine the likelihood of implant-related complications and, in doing so, specific patient outcomes. This paper will review the challenges associated with the use of silicone, saline and "gummy bear" implants in view of their application in patients recovering from breast cancer-related mastectomy, and investigate the opportunities presented by advanced functional nanomaterials in meeting these challenges and potentially opening new dimensions for breast reconstruction. STATEMENT OF SIGNIFICANCE: Breast cancer is a significant cause of morbidity and mortality in women worldwide, which is difficult to prevent or predict, and its treatment carries long-term physiological and psychological consequences. Post-mastectomy breast reconstruction addresses the cosmetic aspect of cancer treatment. Yet, drawbacks of current implants contribute to the development of implant-associated complications, which may lead to prolonged patient care, pain and loss of function. Nanomaterials can help resolve the intrinsic biomechanical mismatch between implant and tissues, enhance mechanical properties of soft implantable materials, and provide an alternative avenue for controlled drug delivery. Here, we explore advances in the use of functionalized nanomaterials to enhance the properties of breast implants, with representative examples that highlight the utility of nanomaterials in addressing key challenges associated with breast reconstruction.

Biofilm formation by staphylococci in health-related environments and recent reports on their control using natural compounds

Staphylococci are Gram-positive bacteria that are ubiquitous in the environment and able to form biofilms on a range of surfaces. They have been associated with a range of human health issues such as medical device-related infection, localized skin infection, or direct infection caused by toxin production. The extracellular material produced by these bacteria resists antibiotics and host defence mechanism which complicates the treatment process. The commonly reported Staphylococcus species are Staphylococcus aureus and S. epidermidis as they inhabit human bodies. However, the emergence of other staphylococci, such as S. haemolyticus, S. lugdunensis, S. saprophyticus, S. capitis, S. saccharolyticus, S. warneri, S. cohnii, and S. hominis, is also of concern and they have been associated with biofilm formation. This review critically assesses recent cases on the biofilm formation by S. aureus, S. epidermidis, and other staphylococci reported in health-related environments. The control of biofilm formation by staphylococci using natural compounds is specifically discussed as they represent potential anti-biofilm agents which may reduce the burden of antibiotic resistance.

Cu-Releasing Bioactive Glass Coatings and Their in Vitro Properties

Bioactive glasses are well-known materials suitable for bone-related applications thanks to their biocompatibility and osteoconductivity. In order to improve their in vivo performance, the modification of the glass composition by adding ions with specific biological functions is required. As copper (Cu) possesses antibacterial properties, in this study, 5 wt % of CuO has been added to the 45S5 bioactive glass composition. The investigation of the effect of the Cu-containing bioactive glass on cellular behavior has revealed that the presence of Cu induces an early differentiation of human mesenchymal stem cells through osteoblast phenotype, promotes the expression of anti-inflammatory interleukin, and reduces proinflammatory interleukin expression. With the aim to produce coatings with antibacterial properties, the Cu-containing bioactive glass was used as the target material for the pulsed laser deposition (PLD) of bioactive thin films. PLD experiments were carried out at different substrate temperatures to study the effect on the film's characteristics. All of the films are compact, crack-free, and characterized by a rough morphology and good wettability. The in vitro bioactivity was demonstrated by the apatite growth on the coating surface, after soaking in simulated body fluid, revealed by Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses. The antibacterial study proved that the material showed more effective activity against three Gram-negative bacteria ( Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica) rather than against Gram-positive bacteria ( Staphylococcus aureus).