Recent Advances in Antimicrobial Coatings and Material Modification Strategies for Preventing Urinary Catheter-Associated Complications

Hemocompatible gelatin-glycidyl methacrylate/graphene oxide composite hydrogels for vascular catheter applications

The development of biocompatible and hemocompatible materials is crucial for various biomedical applications. In this study, gelatin (Gel) was modified using glycidyl methacrylate (GMA) to create a photo-curable macromer (Gel-GMA), facilitating subsequent crosslinking via UV radiation. Additionally, a composite was prepared by incorporating graphene oxide (GO) into the modified gelatin matrix (Gel-GMA/GO). Structural and morphological analyses revealed macroporous or interconnected structures in the hydrogels and composites, resulting in high swelling capacities (> 1050%). Hemolysis testing demonstrated minimal hemolytic activity for both Gel-GMA and Gel-GMA/GO hydrogels, confirming their excellent hemocompatibility (0.54 and 0.50% respectively). Prothrombin time (PT) tests indicated negligible differences compared to normal blood, suggesting low thrombogenicity. The incorporation of GO reduced the PT to 12.9s. Furthermore, in vitro degradation studies under simulated blood conditions revealed moderate degradation rates) for Gel-GMA and Gel-GMA/GO hydrogels (37 and 18%, respectively) after 30 days. Viability assays on MRC-5 cells exposed to composite extracts up to 500 µg/ml showed consistent cell viability (more than 91.7%), with a slight reduction at higher concentrations. These findings underscore the potential of the hydrogels for applications such as vascular catheters, highlighting their biocompatibility, hemocompatibility, and controlled degradability.

1,4-Bis(2-hydroxyethyl)piperazine-derived water-dispersible and antibacterial polyurethane coatings for medical catheters

To prolong usage and mitigate infections associated with bacterial colonization on medical catheters, the development of water-dispersible polyurethane (PU) coatings with bactericidal properties is desirable. With this objective, we have formulated polyurethane coatings that exhibit both antibacterial activity and water dispersibility. A piperazine-based diol, 1,4-bis(2-hydroxyethyl)piperazine (HEPZ), was synthesized and used as a chain extender in PU synthesis. The PUs were prepared using hexamethylene diisocyanate (HDI), 4,4'-methylene diphenyl diisocyanate (MDI), polyethylene glycol (PEG600), and polypropylene glycol (PPG400), resulting in a series of polyurethanes (PU1-PU4). MDI-containing PUs showed superior tensile strength (3.2-3.6 MPa) and elongation (67-70%) attributable to their higher aromatic content. The PEG600-containing PUs (PU1 and PU3) were alkylated using methyl iodide (MeI) to varying degrees whereby a significant reduction in contact angle from ∼82° to ∼62° was observed, indicating enhanced hydrophilicity. MPU3-D with 72.5% methylation demonstrated the most stable water dispersion with a particle size of ∼190.8 nm and a zeta potential of +49.0 mV. In vitro cytocompatibility studies further revealed that methylated PU3 exhibited higher compatibility (80-90%) compared to methylated PU1 (30-40%). The hemolysis test showed the non-hemolytic behavior of MPU3-D films with a % hemolysis of 0.4 ± (0.2)% making it suitable for coating on medical devices. Additionally, MPU3-D films also demonstrated antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, with zones of inhibition measuring 7 mm and 8 mm, respectively. Also, water-dispersible MPU3-D-based coatings with a hardness of ∼75 A and a thickness of ∼17 μm (as observed through FESEM) showed strong adhesion to PVC catheters, exhibiting an adhesion strength of 4B rating. Our results suggest that water-dispersible polyurethane coatings with antibacterial properties are promising materials to reduce catheter-associated infections and enhance patient care.

Fatty Acid-Containing p(HEMA) Hydrogels; A Promising Coating Platform to Reduce Encrustation on Urinary Catheters

Two significant clinical issues associated with the use of urinary catheters are catheter-associated urinary tract infection and encrustation. This study describes the design of novel hydrogels based on fatty acid-containing p(hydroxyethylmethacrylate, HEMA) and their resistance to both microbial adherence and encrustation. Incorporation of fatty acids increased the contact angle (surface hydrophobicity), decreased the ultimate tensile strength only after storage at pH 9 in artificial urine (AU) but not at lower pH values, decreased the Young's modulus and % elongation at break (both stored in deionised water, AU pH 6 and AU pH 9) and decreased equilibrium swelling (only when stored in deionised water or AU pH 6 but not AU pH 9). Moderate reductions in adherence of Escherichia coli, Proteus mirabilis and Staphylococcus epidermidis to certain fatty acid containing (primarily decanoic acid and myristic acid) hydrogels were observed. No relationship was observed between hydrogel contact angle and resistance to microbial attachment. Most fatty acid-containing hydrogels exhibited significant, concentration-dependent resistance to encrustation, postulated to be due both to a greasy film resultant from the formation of the calcium/magnesium fatty acid salts at the surface and the role of Tween® 80 in facilitating the removal of the fatty acid salts from the surface of the hydrogel. The observed enhanced resistance of the hydrogels to encrustation offers opportunities for the use of such systems as platforms for coatings of urinary catheters.

Antibacterial and antifouling materials for urinary catheter coatings

Implantable medical devices have played a significant role in improving both medical care and patients' quality of life. Urinary Catheters (UCs) are commonly utilized as a substitute for bladder drainage and urine collection to prevent urinary retention in patients. However, bacterial colonization and biofilm formation on the catheter surface are prone to occur, leading to catheter-associated urinary tract infections (CAUTIs) and other complications. In recent years, UC coatings have garnered increasing attention. In this review, various antifouling and antibacterial materials for UC coatings are summarized and their impacts on bacterial activities are linked to potential mechanisms of action. Additionally, this review provides an in-depth understanding of the current advancements in UC coatings by presenting the advantages, limitations, notable achievements, and latest research findings. Finally, it anticipates the prospective design and development trajectories of UC coatings in this domain. This holds paramount significance in advancing medical device technology. STATEMENT OF SIGNIFICANCE: Combating catheter-associated urinary tract infections is a major healthcare challenge, and urinary catheter (UC) coatings are considered promising candidates to counter these infections. In this review, various antifouling and antibacterial materials for UCs are summarized, and their impacts on bacterial activities are linked to potential mechanisms of action. Additionally, the review provides an in-depth understanding of the current advancements in UC coatings by presenting the advantages, limitations, notable achievements, and latest research findings. This holds paramount significance in advancing medical device technology. This review not only contributes to the scientific research but also sparks interest among readerships and other researchers in the study of safer and more effective UC coatings for improved patient outcomes.

Dual-Layer Nanoengineered Urinary Catheters for Enhanced Antimicrobial Efficacy and Reduced Cytotoxicity

Catheter-associated urinary tract infection (CAUTI) is the most common healthcare-associated infection; however, current therapeutic strategies remain insufficient for standard clinical application. A novel urinary catheter featuring a dual-layer nanoengineering approach using zinc (Zn) and silver nanoparticles (AgNPs) is successfully fabricated. This design targets microbial resistance, minimizes cytotoxicity, and maintains long-term efficacy. The inner AgNPs layer provides immediate antibacterial effects against the UTI pathogens, while the outer porous Zn layer controls zero-order Ag release and generates reactive oxygen species, thus enhancing long-term bactericidal performance. Enhanced antibacterial properties of Zn/AgNPs-coated catheters are observed, resulting in 99.9% of E. coli and 99.7% of S. aureus reduction, respectively. The Zn/AgNPs-coated catheter significantly suppresses biofilm with sludge formation compared to AgNP-coated and uncoated catheters (all, p < 0.05). The Zn/AgNP-coated catheter in a rabbit model demonstrated a durable, effective barrier against bacterial colonization, maintaining antimicrobial properties during the catheter indwelling period with significantly reduced inflammation and epithelial disruption compared with AgNP and uncoated groups. This innovation has the potential to revolutionize the design of antimicrobial medical devices, particularly for applications requiring long-term implantation. Although further preclinical studies are required to verify its efficacy and safety, this strategy seems to be a promising approach to preventing CAUTI-related complications.

Potential of silver nanoparticles synthesized from Justicia adhatoda metabolites for inhibiting biofilm on urinary catheters

In the present study, we investigated the anti-biofilm effect of urinary catheters fabricated with biogenic nanoparticles synthesized from metabolites of Justicia adhatoda under in vitro conditions against human pathogenic bacteria. Silver nanoparticles were synthesized in the reaction mixture composed of 2 % w/v of 0.1 M of precursor (silver nitrate) and 0.2 g of the metabolites obtained from ethanolic extract of Justicia adhatoda. Characterization of the nanoparticles was done by UV visible spectroscopy, fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X ray diffraction (XRD) to confirm the structural and functional properties. Primary conformation of nanoparticles synthesis by UV visible spectroscopy revealed the notable absorption spectra at 425 nm with a wavelength shift around 450 nm, likely due to surface plasmon resonance excitation. SEM analysis showed spherical, monodisperse, nano scale particles with a size range of 50-60 nm. Crystaline phase of the synthesized nanoparticles was confirmed by x ray diffraction studies which showed the distinct peaks at (2θ) 27.90, 32.20, 46.30, 54.40, and 67.40, corresponding to (111), (200), (220), (222), and (311) planes of nano scale silver. The biocompatibility of these nanoparticles was assessed through zebrafish embryonic toxicity study which showed more than 90 % of embryos were alive and healthy. No marked changes on the blood cells also confirmed best hemocompatibility of the nanoparticles. Synthesized nanoparticles thus obtained were fabricated on the urinary catheter and the fabrication was confirmed by FTIR and SEM analysis. Notable changes in the absorption peaks, uniform coating and embedding of silver nanoparticles studied by FTIR and SEM analysis confirmed the fabrication of silver nanoparticles. The coated catheters demonstrated significant antibacterial activity against pathogenic bacterial strains, including E. coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. Anti-biofilm studies, conducted using a modified microtiter plate crystal violet assay, revealed effective inhibition of both bacterial adhesion and biofilm development. 85 % of biofilm inhibition was recorded against both the tested strains. The coating method presented in this study shows promise for enhancing infection resistance in commonly used medical devices like urinary catheters, thus addressing device-associated infections.

New Antimicrobial Materials Based on Plasticized Polyvinyl Chloride for Urinary Catheters: Preparation and Testing

Given the constant increased number of nosocomial infections in hospitals, especially associated with prolonged usage of inserted medical devices, our work aims to ameliorate clinical experience and promote faster healing of patients undergoing urinary catheterization by improving the properties of medical devices materials. Within this research, nine different composites were prepared based on polyvinyl chloride, using three different plasticizers (di-(2-ethylhexyl) phthalate, Proviplast 2646, and Proviplast 2755), and two different antimicrobial additives containing silver nanoparticles. The prepared materials were analyzed, and their physicochemical properties were determined: water absorption, relative density, plasticizer migration, hydrophobicity/hydrophilicity by contact angle measurement, Shore A hardness, tensile strength, and elongation at break. Structure and morphology were also investigated by means of FTIR, SEM, and EDX analyses, and thermal (TG-DSC) and biological properties were evaluated. The most important aspects of obtained results are showing that plasticizer migration was significantly reduced (to almost zero) and that the usage of antimicrobial additives improved the materials' biocompatibility. Thus, based on the concluded favorable properties, the obtained materials can be further used for catheter development. Pressure-flow studies for different sizes and configurations are the next steps toward advanced in vivo and clinical trials.

Investigation of Chlorhexidine and Chitosan Gel-Based Coatings for the Prevention of Intravascular Catheter-Associated Infections Following Quality by Design Approach

Intravascular catheter-associated infections pose a significant threat to the health of patients because of biofilm formation. Hence, it is imperative to exploit cost-effective approaches to improve patient compliance. With this aim, our present study reported the potential of an antimicrobial polymeric gel coating of chitosan (CS) and chlorhexidine (CHX) on the marketed urinary catheters to minimize the risk of biofilm formation. The study involved the implementation of the Quality by Design (QbD) approach by identifying the critical parameters that can affect the coating of the catheter's surface in any possible way. Later, design of experiments (DoE) analysis affirmed the lack of linearity in the model for the studied responses in a holistic manner. Moreover, in vitro studies were conducted for the evaluation of various parameters followed by the antibiofilm study. The coating exhibited promising release of CHX in the artificial urinary media together with retention of the coating on the catheter's surface. Therefore, this study aims to emphasize the importance of a systematic and quality-focused approach by contributing to the development of a safe, effective, and reliable catheter coating to enhance intravascular catheter safety.

Continuous Catheter Techniques Versus Single-Injection Nerve Blocks: A Comprehensive Review of Postoperative Pain Management Strategies

Effective postoperative pain management is crucial for optimizing patient recovery and enhancing surgical outcomes. This review compares two prominent regional anesthesia techniques, continuous catheter techniques and single-injection nerve blocks, focusing on their efficacy, safety, and impact on patient outcomes. Single-injection nerve blocks involve administering a one-time anesthetic dose to a specific nerve or plexus, offering immediate but transient pain relief. In contrast, continuous catheter techniques utilize a catheter to deliver a continuous infusion of anesthetic, providing extended analgesia. The review synthesizes current evidence on the effectiveness of each method, highlighting that single-injection blocks are advantageous for their simplicity and rapid onset but may require supplementary pain management for longer procedures. Continuous catheter techniques, while offering prolonged pain relief, carry risks such as infection and catheter displacement. The comparative analysis of these techniques reveals that both have distinct roles in postoperative care, with choice depending on the surgical procedure and patient needs. Patient satisfaction, recovery times, and overall outcomes are critical factors in determining the optimal pain management strategy. Future research should focus on refining these techniques and exploring innovations to improve patient care and pain management outcomes. This review provides insights for clinicians to make informed decisions about postoperative pain management to enhance patient comfort and recovery.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

Medical devices such as venous catheters (VCs) and urinary catheters (UCs) are widely used in the hospital setting. However, the implantation of these devices is often accompanied by complications. About 60 to 70% of nosocomial infections (NIs) are linked to biofilms. The main complication is the ability of microorganisms to adhere to surfaces and form biofilms which protect them and help them to persist in the host. Indeed, by crossing the skin barrier, the insertion of VC inevitably allows skin flora or accidental environmental contaminants to access the underlying tissues and cause fatal complications like bloodstream infections (BSIs). In fact, 80,000 central venous catheters-BSIs (CVC-BSIs)-mainly occur in intensive care units (ICUs) with a death rate of 12 to 25%. Similarly, catheter-associated urinary tract infections (CA-UTIs) are the most commonlyhospital-acquired infections (HAIs) worldwide.These infections represent up to 40% of NIs.In this review, we present a summary of biofilm formation steps. We provide an overview of two main and important infections in clinical settings linked to medical devices, namely the catheter-asociated bloodstream infections (CA-BSIs) and catheter-associated urinary tract infections (CA-UTIs), and highlight also the most multidrug resistant bacteria implicated in these infections. Furthermore, we draw attention toseveral useful prevention strategies, and advanced antimicrobial and antifouling approaches developed to reduce bacterial colonization on catheter surfaces and the incidence of the catheter-related infections.

Novel Antimicrobial Approaches to Combat Bacterial Biofilms Associated with Urinary Tract Infections

Urinary tract infections (UTIs) are prevalent bacterial infections in both community and healthcare settings. They account for approximately 40% of all bacterial infections and require around 15% of all antibiotic prescriptions. Although antibiotics have traditionally been used to treat UTIs for several decades, the significant increase in antibiotic resistance in recent years has made many previously effective treatments ineffective. Biofilm on medical equipment in healthcare settings creates a reservoir of pathogens that can easily be transmitted to patients. Urinary catheter infections are frequently observed in hospitals and are caused by microbes that form a biofilm after a catheter is inserted into the bladder. Managing infections caused by biofilms is challenging due to the emergence of antibiotic resistance. Biofilms enable pathogens to evade the host's innate immune defences, resulting in long-term persistence. The incidence of sepsis caused by UTIs that have spread to the bloodstream is increasing, and drug-resistant infections may be even more prevalent. While the availability of upcoming tests to identify the bacterial cause of infection and its resistance spectrum is critical, it alone will not solve the problem; innovative treatment approaches are also needed. This review analyses the main characteristics of biofilm formation and drug resistance in recurrent uropathogen-induced UTIs. The importance of innovative and alternative therapies for combatting biofilm-caused UTI is emphasised.

Purple Urine Bag Syndrome in a Home-Dwelling Elderly Female with Lumbar Compression Fracture: A Case Report

Purple urine bag syndrome (PUBS) is an uncommon, but usually benign, underrecognized clinical condition with the distressing presentation of purple, blue or reddish discoloration of a patient's catheter bag and tubing in the setting of catheter-associated urinary tract infections (UTIs). PUBS is the result of the complex metabolic pathway of the dietary essential amino acid tryptophan. Its urinary metabolite, indoxyl sulfate, is converted into red and blue byproducts (indirubin and indigo) in the presence of the bacterial enzymes indoxyl sulfatase and phosphatase. The typical predisposing factors are numerous and include the following: female gender, advanced age, long-term catheterization and immobilization, constipation, institutionalization, dementia, increased dietary intake of tryptophan, chronic kidney disease, alkaline urine, and spinal cord injury (SCI). Here, we present a case of PUBS in a home-dwelling elderly female patient with a history of long-term immobility after a pathological spinal fracture, long-term catheterization, constipation, and malignant disease in remission. Urine culture was positive for Proteus mirabilis. This state can be alarming to both patients and physicians, even if the patient is asymptomatic. Healthcare professionals and caregivers need to be aware of this unusual syndrome as an indicator of bacteriuria in order to initiate proper diagnostics and treatment.

Emerging evidence-based innovative approaches to control catheter-associated urinary tract infection: a review

Healthcare settings have dramatically advanced the latest medical devices, such as urinary catheters (UC) for infection, prevention, and control (IPC). The continuous or intermittent flow of a warm and conducive (urine) medium in the medical device, the urinary catheter, promotes the formation of biofilms and encrustations, thereby leading to the incidence of CAUTI. Additionally, the absence of an innate immune host response in and around the lumen of the catheter reduces microbial phagocytosis and drug action. Hence, the review comprehensively overviews the challenges posed by CAUTI and associated risks in patients' morbidity and mortality. Also, detailed, up-to-date information on the various strategies that blended/tailored the surface properties of UC to have anti-fouling, biocidal, and anti-adhesive properties to provide an outlook on how they can be better managed with futuristic solutions.

Expanding Quality by Design Principles to Support 3D Printed Medical Device Development Following the Renewed Regulatory Framework in Europe

The vast scope of 3D printing has ignited the production of tailored medical device (MD) development and catalyzed a paradigm shift in the health-care industry, particularly following the COVID pandemic. This review aims to provide an update on the current progress and emerging opportunities for additive manufacturing following the introduction of the new medical device regulation (MDR) within the EU. The advent of early-phase implementation of the Quality by Design (QbD) quality management framework in MD development is a focal point. The application of a regulatory supported QbD concept will ensure successful MD development, as well as pointing out the current challenges of 3D bioprinting. Utilizing a QbD scientific and risk-management approach ensures the acceleration of MD development in a more targeted way by building in all stakeholders' expectations, namely those of the patients, the biomedical industry, and regulatory bodies.