In vitro evaluation of novel antimicrobial coatings for surgical sutures using octenidine

Evaluation of Physical Properties of Coated Polydioxanone Threads

BACKGROUND

Using a thread for wound closure promotes healing and minimizes contamination by foreign substances. Threads have also been employed in esthetic surgery; however, functional threads that can improve wrinkles and rejuvenate the skin are required.

OBJECTIVE

To evaluate the suitability of polydioxanone threads coated with polyethylene glycol, hyaluronic acid, and amino acids for use in the medical field because such formulations are expected to promote regeneration and collagen synthesis.

MATERIALS AND METHODS

Physical properties (diameter [ n = 20], tensile strength [ n = 20], strength retention rate [ n = 10], and scanning electron microscopy images) and cytotoxicity (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays) of polydioxanone threads coated with polyethylene glycol, hyaluronic acid, and amino acids were assessed and compared with those of uncoated polydioxanone threads. Analyses were performed using IBM SPSS Statistics (Statistical significance; p values <.05).

RESULTS

The size standards for tensile strength (≥63.5 N) and diameter (average 0.570-0.610 mm) were met. There were no differences in the physical properties of the coated and uncoated threads; however, the biocompatibility of coated threads was high owing to low cytotoxicity.

CONCLUSION

Threads coated with materials that can promote regeneration are suitable for use in the medical field.

Drug-Eluting Sutures by Hot-Melt Extrusion: Current Trends and Future Potentials

Surgical site infections (SSIs) may result from surgical procedures requiring a secondary administration of drugs at site or systemically in treating the infection. Drug-eluting sutures containing antimicrobial agents symbolise a latent strategy that precludes a secondary drug administration. It also offers the possibility of delivering a myriad of therapeutic agents to a localised wound site to effect analgesia, anti-inflammation, or the deployment of proteins useful for wound healing. Further, the use of biodegradable drug-eluting sutures eliminates the need for implanting foreign material into the wound, which needs to be removed after healing. In this review, we expound on recent trends in the manufacture of drug-eluting sutures with a focus on the hot-melt extrusion (HME) technique. HME provides a solvent-free, continuous one-step manufacturing conduit for drug-eluting sutures, hence, there is no drying step, which can be detrimental to the drug or suture threads and, thus, environmentally friendly. There is the possibility of combining the technology with additive manufacturing platforms to generate personalised drug-loaded implantable devices through prototyping and scalability. The review also highlights key material requirements for fabricating drug-eluting sutures by HME, as well as quality attributes. Finally, a preview of emerging drug-eluting sutures and advocacy for harmonisation of quality assurance by regulatory authorities that permits quality evaluation of novelty sutures is presented.

Enhancing Dental Applications: A Novel Approach for Incorporating Bioactive Substances into Textile Threads

In the realm of surgical and dental applications, hyaluronic acid (HA) braided threads show significant therapeutic potential due to their incorporation of pharmaceutical active ingredients. This study primarily focuses on resolving the crucial challenge of devising a deposition method that can ensure both precision and uniformity in the content of the active ingredient Octenidine dihydrochloride (OCT) within each segment of the threads. Our objective in this study was to develop a continuous deposition method for OCT onto a braided thread composed of 24 hyaluronic acid-based fibers, aiming for a specific OCT content of 0.125 µg/mm, while maintaining a maximum allowable deviation of ±15% in OCT content. The motivation behind designing this novel method stemmed from the necessity of employing a volatile solvent for the active agent. Conventional wetting methods proved unsuitable due to fluctuations in the solution's concentration during deposition, and alternative methods known to us demanded intricate technical implementations. The newly introduced method offers distinct advantages, including its online processing speed, scalability potential, and cost-efficiency of the active agent solution. Additionally, it minimizes the impact on the natural polymer thread, preserving energy by obviating the need for complete thread saturation. Our research and precise apparatus development resulted in achieving the desired thread properties, with an OCT content of (1.51 ± 0.09) µg per 12 mm thread piece. These findings not only validate the suitability of this innovative method for depositing active agents but also extend its potential applicability beyond dental care.

[Surgical suture material-fundamentals]

At the end of surgical therapy, the access is closed with sutures. Surgical sutures are thus used to adapt wound edges and tissues. The task of the suture material is to hold the tissues together until healing. For patients, a cosmetically good suture is often the sign of good surgery. Different tissues and layers have different requirements regarding the suture material. The different types from monofil to polyfil, braided, from absorbable to nonabsorbable are presented. The classification of suture strengths is compared. The areas of application of different strengths and the duration until removal of the sutures for the different body regions are presented. The one-hand and two-hand techniques of surgical knots are explained in detail. The technique of suture removal is presented. In the online material, the suture materials of different composition and manufacturers can be compared.

The potential of microalgal sources as coating materials: A case study for the development of biocompatible surgical sutures

Sutures are considered as surgical materials that form excellent surfaces to integrate the postoperative parts of the body. These materials present suitable platforms for potential bacterial penetrations. Therefore, coating these biomedical materials with biocompatible compounds is seen as a potential approach to improve their properties while avoiding adverse effects. The aim of this study was to evaluate Arthrospira platensis, Haematacoccus pluvialis, Chlorella minutissima, Botyrococcus braunii, and Nostoc muscorum as potential surgical suture coating materials. Their crude extracts were absorbed into two different sutures as poly glycolic (90%)-co-lactic acid (10%) (PGLA) and poly dioxanone (PDO); then, their cytotoxic effects and antibacterial activities were examined. Both N. muscorum-coated sutures (PGLA and PDO) and A. platensis-coated (PGLA and PDO) sutures did not induce any toxic effect on L929 mouse fibroblast cells (>70% cell viability). The highest antibacterial activity against Staphylococcus aureus was achieved with N. muscorum-coated PGLA and A. platensis-coated PGLA at 11.18 ± 0.54 mm and 9.52 ± 1.15 mm, respectively. These sutures were examined by mechanical analysis, and found suitable according to ISO 10993-5. In comparison with the commercial antibacterial agent (chlorohexidine), the results proved that N. muscorum extract can be considered as the most promising suture coating material for the human applications.

A discrete shear lag model of the mechanics of hitchhiker plants, and its prospective application to tendon-to-bone repair

Tendon-to-bone repairs often fail when sutures pull through tendon, like a wire through cheese. Repair strength is maximized when loads are balanced equally among all sutures, relative to the pullout resistance of the tendon and the strength of the sutures. This problem of balancing loads across multiple, discrete attachment sites has been solved in nature by hitchhiker plants that proliferate by adhering relatively stiff fruit to relatively soft fur and fabrics through arrays of hooks. We, therefore, studied the fruits of such a plant, Harpagonella palmeri , and developed a discrete shear lag analysis of the force distributions in H. palmeri 's linear arrays of long, slender hooks of varied lengths and spacing. Results suggested that strategies were used by the plant to distribute loads, including variations in the spacing and stiffnesses of hooks that serve to equalize forces over attachment sites. When applying these models to suturing schemes for surgical reattachment of tendon to bone, results suggested that strategies exhibited by H. palmeri show promise for balancing forces over sutures, potentially doubling repair strength relative to what could be achieved with a uniform suture distribution. Results suggest a potential pathway for strengthening surgical repairs, and more broadly for optimizing fasteners for bi-material attachment.

Effect of antimicrobial peptide conjugated surgical sutures on multiple drug-resistant microorganisms

Surgical site infections are commonly encountered as a risk factor in clinics that increase the morbidity of a patient after a surgical operation. Surgical sutures are one of the leading factor for the formation of surgical site infections that induce bacterial colonization by their broad surface area. Current strategies to overcome with surgical site infections consist utilization of antibiotic agent coatings such as triclosan. However, the significant increase in antibiotic resistance majorly decreases their efficiency against recalcitrant pathogens such as; Pseudomonas aeruginosa and Staphylococcus aureus. Therefore, the development of a multi drug-resistant antimicrobial suture without any cytotoxic effect to combat surgical site infections is vital. Antimicrobial peptides are the first defense line which has a broad range of spectrum against Gram-positive, and Gram-negative bacteria and even viruses. In addition, antimicrobial peptides have a rapid killing mechanism which is enhanced by membrane disruption and inhibition of functional proteins in pathogens without the development of antimicrobial resistance. In the scope of the current study, the antimicrobial effect of antimicrobial peptide conjugated poly (glycolic acid-co-caprolactone) (PGCL) sutures were investigated against P. aeruginosa and methicillin-resistant S. aureus (MRSA) strains by using antimicrobial peptide sequences of KRFRIRVRV-NH₂, RWRWRWRW-NH₂ and their dual combination (1:1). In addition, in vitro wound scratch assays were performed to evaluate the effect of antimicrobial peptide conjugated sutures on keratinocyte cell lines. Our results indicated that antimicrobial peptide modified sutures could be a potential novel medical device to overcome surgical site infections by the superior acceleration of wound healing.

Applications of Electrospun Drug-Eluting Nanofibers in Wound Healing: Current and Future Perspectives

Wounds are a consequence of disruption in the structure, integrity, or function of the skin or tissue. Once a wound is formed following mechanical or chemical damage, the process of wound healing is initiated, which involves a series of chemical signaling and cellular mechanisms that lead to regeneration and/or repair. Disruption in the healing process may result in complications; therefore, interventions to accelerate wound healing are essential. In addition to mechanical support provided by sutures and traditional wound dressings, therapeutic agents play a major role in accelerating wound healing. The medicines known to improve the rate and extent of wound healing include antibacterial, anti-inflammatory, and proliferation enhancing agents. Nonetheless, the development of these agents into eluting nanofibers presents the possibility of fabricating wound dressings and sutures that provide mechanical support with the added advantage of local delivery of therapeutic agents to the site of injury. Herein, the process of wound healing, complications of wound healing, and current practices in wound healing acceleration are highlighted. Furthermore, the potential role of drug-eluting nanofibers in wound management is discussed, and lastly, the economic implications of wounds as well as future perspectives in applying fiber electrospinning in the design of wound dressings and sutures are considered and reported.

Contact Dermatitis in the Surgical Patient: A Focus on Wound Closure Materials

ABSTRACT

Irritant and allergic contact dermatitis from wound closure materials can occur in patients after surgical procedures. The resulting inflammation from contact dermatitis can compromise wound healing, mimic surgical site infections, and result in wound dehiscence. Components of wound closure material, such as antibiotic coatings, dyes, sterilizing compounds, or the material itself, have been implicated as contact allergens. This article provides the latest overview of the components of 3 major forms of wound closure materials-sutures, staples, and tissue adhesives-associated with contact dermatitis, discusses their cross-reactivity, and provides diagnostic and treatment guidelines.

Synthesis of a novel monofilament bioabsorbable suture for biomedical applications

In this research, a novel bioabsorbable suture that is, monofilament and capable of localized drug delivery, was developed from a combination of natural biopolymers that where not previously applied for this purpose. The optimized suture formulation comprised of sodium alginate (6% wt/vol), pectin (0.1% wt/vol), and gelatin (3% wt/vol), in the presence of glycerol (4% vol/vol) which served as a plasticizer. The monofilament bioabsorbable sutures where synthesized via in situ ionic crosslinking in a barium chloride solution (2% wt/vol). The resulting suture was characterized in terms of mechanical properties, morphology, swelling, degradation, drug release, and biocompatibility, in addition to Fourier-transform infrared (FTIR) spectroscopy, Powder X-ray Diffraction (PXRD) and Differential Scanning Calorimetry (DSC) analysis. The drug loaded and non-drug loaded sutures had a maximum breaking strength of 4.18 and 4.08 N, in the straight configuration and 2.44 N and 2.59 N in the knot configuration, respectively. FTIR spectrum of crosslinked sutures depicted Δ9 cm^-1 downward shift for the carboxyl stretching band which was indicative of ionic interactions between barium ions and sodium alginate. In vitro analysis revealed continued drug release for 7 days and gradual degradation by means of surface erosion, which was completed by day 28. Biocompatibility studies revealed excellent hemocompatibility and no cytotoxicity. These results suggest that the newly developed bioabsorbable suture meets the basic requirements of a suture material and provides a viable alternative to the synthetic polymer sutures that are currently on the market.

Wound Antiseptics and European Guidelines for Antiseptic Application in Wound Treatment

Issues arising in wound healing are very common, and chronic wound infections affect approximately 1.5% of the population. The main substances used in wound washing, cleansing and treatment are antiseptics. Today, there are many compounds with a known antiseptic activity. Older antiseptics (e.g., boric acid, ethacridine lactate, potassium permanganate, hydrogen peroxide, iodoform, iodine and dyes) are not recommended for wound treatment due to a number of disadvantages. According to the newest guidelines of the Polish Society for Wound Treatment and the German Consensus on Wound Antisepsis, only the following antiseptics should be taken into account for wound treatment: octenidine (OCT), polihexanide (PHMB), povidone-iodine (PVP-I), sodium hypochlorite (NaOCl) and nanosilver. This article provides an overview of the five antiseptics mentioned above, their chemical properties, wound applications, side effects and safety.

Sustainable Antibacterial Surgical Suture Using a Facile Scalable Silk-Fibroin-Based Berberine Loading System

Medical sutures with sustainable antibacterial properties can effectively inhibit pathogens, thus avoiding the occurrence of surgical site infection and reducing the recurrence of patients resulting in postoperative death. This paper describes a facile scalable antibacterial surgical suture with sustainable antibacterial function and fair mechanical and biocompatible properties using a simple, efficient, and eco-friendly method. Silk filaments were braided into a core-shell structure using a braiding machine, and then silk fibroin (SF) films loaded with different percentages of berberine (BB) were coated onto the surface of the suture. The drug-loaded sutures performed a slow drug-release profile of more than 7 days. Retention of the knot-pull tensile strength of all groups was above 87% during in vitro degradation within 42 days. The sutures had no toxicity to the cells' in vitro cytotoxicity. The results of the in vivo biocompatibility test showed mild inflammation and clear signs of supporting angiogenesis in the implantation site of the rats. This work provides a new route for achieving a BB-loaded and high-performance antibacterial suture, which is of great potential in applications for surgical operations.

Engineering and polymeric composition of drug-eluting suture: A review

Sutures are the most popular surgical implants in the global surgical equipment market. They are used for holding tissues together to achieve wound closure. However, controlling the body's immune response to these "foreign bodies" at site of infection is challenging. Natural polymers such as collagen, silk, nylon, and cotton, and synthetic polymers such as polycaprolactone, poly(lactic-co-glycolic acid), poly(p-dioxanone) and so forth, contribute the robust foundation for the engineering of drug-eluting sutures. The incorporation of active pharmaceutical ingredients (APIs) with polymeric composition of suture materials is an efficient way to reduce inflammatory reaction in the wound site as well as to control bacterial growth, while allowing wound healing. The incorporation of polymeric composition in surgical sutures has been found to add high flexibility as well as excellent physical and mechanical properties. Fabrication processes and polymer materials allow control over drug-eluting profiles to effectively address wound healing requirements. This review outlines and discusses (a) polymer materials and APIs used in suture applications, including absorbable and nonabsorbable sutures; (b) suture structures, such as monofilament, multifilament, barded and smart sutures; and (c) the existing manufacturing techniques for drug-eluting suture production, including electrospinning, melt-extrusion and coating.

In vitro evaluation of antibacterial efficacy of vancomycin-loaded suture tapes and cerclage wires

Usage of implants containing antibiotic agents has been a common strategy to prevent implant related infections in orthopedic surgery. Unfortunately, most implants with microbial repellent properties are characterized by accessibility limitations during daily clinical practice. Aim of this in vitro study was to investigate whether suture tapes and cerclage wires, which were treated with vancomycin, show a sustainable antibacterial activity. For this purpose, we used 24 stainless steel wire cerclages and 24 ultra-high molecular weight polyethylene and polyester suture tape test bodies. The test bodies were incubated for 30 min. in 100 mg/ml vancomycin solution or equivalent volumes of 0.9% NaCl. After measuring the initial solution uptake of the test bodies, antibacterial efficacy via agar diffusion test with Staphylococcus aureus and vancomycin elution tests were performed 1, 2, 3, and 6 days after incubation. Vancomycin-loaded tapes as well as vancomycin-loaded cerclage wires demonstrated increased bacterial growth inhibition when compared to NaCl-treated controls. Vancomycin-loaded tapes showed an additional twofold and eightfold increase of bacterial growth inhibition compared to vancomycin-loaded wires at day 1 and 2, respectively. Elution tests at day 1 revealed high levels of vancomycin concentration in vancomycin loaded tapes and wires. Additionally, the concentration in vancomycin loaded tapes was 14-fold higher when compared to vancomycin loaded wires. Incubating suture tapes and cerclage wires in vancomycin solution showed a good short-term antibacterial activity compared to controls. Considering the ease of vancomycin application on suture tapes or wires, our method could represent an attractive therapeutic strategy in biofilm prevention in orthopedic surgery.

Fabrication and characterisation of melt-extruded chitosan/keratin/PCL/PEG drug-eluting sutures designed for wound healing

Diclofenac potassium loaded sutures based upon PEG/PCL/chitosan-keratin blends were fabricated using the hot-melt extrusion technique. Polymer sutures were evaluated based on their physical, thermal and mechanical properties, while the drug-eluting sutures were evaluated for drug release properties. Lastly, the performance of the drug-loaded sutures in the contact with the human keratinocyte cell line HaCat were assessed. Results showed that the sutures extruded homogeneously at a temperature of 63 ± 1 °C providing a uniform thickness of fibres. Analysis by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) showed that completely amorphous and miscible solid dispersions were created. Fourier transform infrared (FTIR) spectroscopy indicated that the presence of hydrogen bonds between the polymers improved material miscibility. Tensile properties of the sutures were clearly affected by the PEG, chitosan and keratin additions. The optimal formulation of tensile strength was obtained when PCL/PEG/chitosan-keratin were combined at a ratio of 80/19/1 w/w. Rapid and sustained drug release rates were achieved with the PEG/PCL/chitosan/keratin blends at various combinations. The composite of PCL/PEG/chitosan-keratin with 30 wt% of diclofenac potassium also exhibited high cell viability and wound healing rates in vitro cytotoxicity testing. The anti-inflammatory properties imparted by the PCL/PEG/chitosan/keratin/drug sutures may further the use of composite sutures for wound healing in clinical settings.

Assessment of agonistic and antagonistic properties of widely used oral care antimicrobial substances toward steroid estrogenic and androgenic receptors

Personal care product consumption has increased in the last decades. A typical representative ingredient, i.e., triclosan, was identified in the scientific literature as an endocrine disruptor, and its use is restricted in several applications. Oral hygiene formulations contain various compounds, including synthetic phenol derivatives, quaternary ammonium compounds (QACs), various amides and amines, or natural essential oils containing terpenes. The aim of this paper was to explore possible endocrine-disrupting effects of these most-used compounds. For this purpose, two different assays based on recombinant yeast (BMAEREluc/ERα; BMAEREluc/AR) and human cell lines (T47D; AIZ-AR) were employed to investigate the agonistic and antagonistic properties of these compounds on human estrogen and androgen receptors. The results showed that none of the compounds were indicated as agonists of the steroid receptors. However, octenidine (OCT, QAC-like) and hexadecylpyridinium (HDP, QAC) were able to completely inhibit both androgenic (IC₅₀ OCT = 0.84 μM; IC₅₀ HDP = 1.66 μM) and estrogenic (IC₅₀ OCT = 0.50 μM; IC₅₀ HDP = 1.64 μM) signaling pathways in a dose-dependent manner. Additionally, chlorhexidine was found to inhibit the 17β-estradiol response, with a similar IC₅₀ (2.9 μM). In contrast, the natural terpenes thymol and menthol were found to be competitive antagonists of the receptors; however, their IC₅₀ values were higher (by orders of magnitude). We tried to estimate the risk associated with the presence of these compounds in environmental matrices by calculating hazard quotients (HQs), and the calculated HQs were found to be close to or greater than 1 only when predicted environmental concentrations were used for surface waters.

Nonfouling textiles with tunable antimicrobial activity based on a zwitterionic polyamine finish

Depending on the degree of substitution DS, the antiadhesive (high DS) or antimicrobial (lower DS) character of the coating will be dominant.

Effect of Hyaluronic Acid Added to Suture Material and its Relationship with Bacterial Colonization: An In vitro Study

Aims and Objectives:

The aims of this study were to evaluate the presence of Staphylococcus aureus and Escherichia coli, in polyglycolic acid (PGA) 4-0 and silk sutures, with or without hyaluronic acid (HA) treatment.

Materials and Methods:

This in vitro study measured S. aureus and E. coli growth on PGA and silk sutures, through incubation in agar media for 24 h. The suture length was 10 cm and divided into three parts: A (8 h), B (16 h), and C (24 h), which were observed every 8 h, followed by suspension on a microscopic slide. This was repeated thrice. The number of S. aureus and E. coli cells was recorded and compared between the suture types.

Results:

The mean S. aureus colony forming units (CFUs) differed at each time point between non-HA and HA-PGA sutures (P = 0.0016), with a greater number of CFUs on non-HA-PGA. The mean S. aureus CFUs were significantly higher on non-HA silk than on HA-silk sutures (P = 0.008). There was a significant increase in E. coli CFUs on non-HA silk than on HA-silk sutures (P = 0.008). E. coli CFUs were higher on non-HA-PGA than on HA-PGA sutures (P = 0.006). We performed repeated measures two-way ANOVA (SPSS version 13.0) for comparison between group factors and time points and Posthoc analysis using independent samples t-test.

Conclusions:

HA reduced wicking in both PGA and silk sutures.

[Local antibiotic therapy]

The treatment of superficial wound infections with local antibiotics is considered to be problematic as it is accompanied by an increased risk of resistance development and ineffectiveness in deeper regions. On the contrary, the local application of antibiotics is useful in arthroplasty and necessary if implants are utilized. The reason for this is the prevention of a rapid biofilm formation on foreign implants and a resulting infection may remain undiscovered until it becomes chronic. Apart from exogenous material, necrotic tissue (e. g. bone sequestra) provides suitable retreat areas for pathogens in the body. Because of the characteristics of bone and joint infections and an exceptional infection recurrence rate, a combined approach is required. Systemic antibiotic prophylaxis is able to reduce the number of pathogens acquired by perioperative contamination or hematogenic spread from another focus of infection; however, systemically applied antibiotics often fail to form an effective colonization barrier around the implant because their ability to penetrate the bone is relatively low. On the other hand, the high concentration of locally released antibiotics leads to an effective protection of the implant from bacteria in situ. Thus, for the treatment of implant-associated infections, systemic and local application of anti-infective agents is a reliable adjuvant measure that improves the therapeutic success. Polymethylmethacrylate (PMMA) bone cement is the most commonly used local drug carrier. Based on clinical and microbiological results, microbiologists and infectious disease experts together with the surgeon and pharmacist determine which anti-infective agents are indicated for systemic and local, PMMA cement-related application. Because there is no evident concept for the local application, unlike the recommendation for systemic use of anti-infective agents, this review article describes which aspects should be taken into account.

Prevention of bacterial colonization on non-thermal atmospheric plasma treated surgical sutures for control and prevention of surgical site infections

Surgical site infections have a remarkable impact on morbidity, extended hospitalization and mortality. Sutures strongly contribute to development of surgical site infections as they are considered foreign material in the human body. Sutures serve as excellent surfaces for microbial adherence and subsequent colonization, biofilm formation and infection on the site of a surgery. Various antimicrobial sutures have been developed to prevent suture-mediated surgical site infection. However, depending on the site of surgery, antimicrobial sutures may remain ineffective, and antimicrobial agents on them might have drawbacks. Plasma, defined as the fourth state of matter, composed of ionized gas, reactive oxygen and nitrogen species, free radical and neutrals, draws attention for the control and prevention of hospital-acquired infections due to its excellent antimicrobial activities. In the present study, the efficacy of non-thermal atmospheric plasma treatment for prevention of surgical site infections was investigated. First, contaminated poly (glycolic-co-lactic acid), polyglycolic acid, polydioxanone and poly (glycolic acid-co-caprolactone) sutures were treated with non-thermal atmospheric plasma to eradicate contaminating bacteria like Staphylococcus aureus and Escherichia coli. Moreover, sutures were pre-treated with non-thermal atmospheric plasma and then exposed to S. aureus and E. coli. Our results revealed that non-thermal atmospheric plasma treatment effectively eradicates contaminating bacteria on sutures, and non-thermal atmospheric plasma pre-treatment effectively prevents bacterial colonization on sutures without altering their mechanical properties. Chemical characterization of sutures was performed with FT-IR and XPS and results showed that non-thermal atmospheric plasma treatment substantially increased the hydrophilicity of sutures which might be the primary mechanism for the prevention of bacterial colonization. In conclusion, plasma-treated sutures could be considered as novel alternative materials for the control and prevention of surgical site infections.

Micellar chemotherapeutic platform based on a bifunctional salicaldehyde amphiphile delivers a "combo-effect" for heightened killing of MRSA

The devastating infections caused by methicillin-resistant Staphylococcus aureus (MRSA) coupled with its high resistance towards antibiotics underscores the need for an effective anti-MRSA therapeutic. The present study illustrates the use of a salicylaldehyde based bactericidal amphiphile (C1) in generating a micellar carrier that renders delivery of therapeutic antibiotics. The inherent membrane-targeting activity of C1 present in the micelle could be leveraged to counter the resistance of MRSA and enhance cellular uptake of the released antibiotics, resulting in effective elimination of the pathogen. The inherent bactericidal and antibiofilm activity of C1 was captured in FESEM analysis, solution-based assays and fluorescence microscopy. ANS-based fluorescence spectroscopy indicated that the critical micelle concentration (CMC) for C1 was 18.5 μM in water. DLS studies and FESEM analysis indicated that the average particle size for micelles based on C1 (C1_M) and rifampicin-loaded C1_M (C1_M- R) was smaller than vancomycin-loaded C1_M (C1_M- V). C1_M- R and C1_M- V rendered sustained release of the antibiotics in physiologically relevant fluids. Notably, following interaction with MRSA for 3 h, the relative anti-MRSA activity of C1_M- R and C1_M- V was nearly 12-fold and 8-fold higher, respectively, as compared to the free antibiotics at equivalent concentration, highlighting the merit of leveraging the activity of C1 and the antibiotic concurrently in the micellar system. The relative cell-free antibiotic was also manifold lower in the case of C1_M- R and C1_M- V treated MRSA as against treatment with free antibiotics, suggesting that the amphiphilic warhead breached the membrane barrier and enhanced cellular uptake of the released antibiotics. Interestingly, C1_M- R and C1_M- V exhibited a high therapeutic index, being non-toxic to HEK 293 cells at concentrations higher than their minimum inhibitory concentration (MIC) against MRSA and they could be employed as an antibacterial coating to prevent MRSA biofilm formation on surgical silk sutures. The antibiotic-replete biocompatible micelles based on a self-assembling membrane-targeting amphiphile described herein represent a promising framework to integrate multiple warheads and generate a potent anti-MRSA therapeutic material.

Viable adhered Staphylococcus aureus highly reduced on novel antimicrobial sutures using chlorhexidine and octenidine to avoid surgical site infection (SSI)

BACKGROUND

Surgical sutures can promote migration of bacteria and thus start infections. Antiseptic coating of sutures may inhibit proliferation of adhered bacteria and avoid such complications.

OBJECTIVES

This study investigated the inhibition of viable adhering bacteria on novel antimicrobially coated surgical sutures using chlorhexidine or octenidine, a critical factor for proliferation at the onset of local infections. The medical need, a rapid eradication of bacteria in wounds, can be fulfilled by a high antimicrobial efficacy during the first days after wound closure.

METHODS

As a pretesting on antibacterial efficacy against relevant bacterial pathogens a zone of inhibition assay was conducted with middle ranged concentrated suture coatings (22 μg/cm). For further investigation of adhering bacteria in detail the most clinically relevant Staphylococcus aureus (ATCC®49230™) was used. Absorbable braided sutures were coated with chlorhexidine-laurate, chlorhexidine-palmitate, octenidine-laurate, and octenidine-palmitate. Each coating type resulted in 11, 22, or 33 μg/cm drug content on sutures. Scanning electron microscopy (SEM) was performed once to inspect the coating quality and twice to investigate if bacteria have colonized on sutures. Adhesion experiments were assessed by exposing coated sutures to S. aureus suspensions for 3 h at 37°C. Subsequently, sutures were sonicated and the number of viable bacteria released from the suture surface was determined. Furthermore, the number of viable planktonic bacteria was measured in suspensions containing antimicrobial sutures. Commercially available sutures without drugs (Vicryl®, PGA Resorba®, and Gunze PGA), as well as triclosan-containing Vicryl® Plus were used as control groups.

RESULTS

Zone of inhibition assay documented a multispecies efficacy of novel coated sutures against tested bacterial strains, comparable to most relevant S. aureus over 48 hours. SEM pictures demonstrated uniform layers on coated sutures with higher roughness for palmitate coatings and sustaining integrity of coated sutures. Adherent S. aureus were found via SEM on all types of investigated sutures. The novel antimicrobial sutures showed significantly less viable adhered S. aureus bacteria (up to 6.1 log) compared to Vicryl® Plus (0.5 log). Within 11 μg/cm drug-containing sutures, octenidine-palmitate (OL11) showed the highest number of viable adhered S. aureus (0.5 log), similar to Vicryl® Plus. Chlorhexidine-laurate (CL11) showed the lowest number of S. aureus on sutures (1.7 log), a 1.2 log greater reduction. In addition, planktonic S. aureus in suspensions were highly inhibited by CL11 (0.9 log) represents a 0.6 log greater reduction compared to Vicryl® Plus (0.3 log).

CONCLUSIONS

Novel antimicrobial sutures can potentially limit surgical site infections caused by multiple pathogenic bacterial species. Therefore, a potential inhibition of multispecies biofilm formation is assumed. In detail tested with S. aureus, the chlorhexidine-laurate coating (CL11) best meets the medical requirements for a fast bacterial eradication. This suture coating shows the lowest survival rate of adhering as well as planktonic bacteria, a high drug release during the first-clinically most relevant- 48 hours, as well as biocompatibility. Thus, CL11 coatings should be recommended for prophylactic antimicrobial sutures as an optimal surgical supplement to reduce wound infections. However, animal and clinical investigations are important to prove safety and efficacy for future applications.

Preventing Surgical Site Infections Using a Natural, Biodegradable, Antibacterial Coating on Surgical Sutures

Surgical site infections (SSIs) are one of the most common nosocomial infections, which can result in serious complications after surgical interventions. Foreign materials such as implants or surgical sutures are optimal surfaces for the adherence of bacteria and subsequent colonization and biofilm formation. Due to a significant increase in antibiotic-resistant bacterial strains, naturally occurring agents exhibiting antibacterial properties have great potential in prophylactic therapies. The aim of this study was to develop a coating for surgical sutures consisting of the antibacterial substance totarol, a naturally occurring diterpenoid isolated from Podocarpustotara in combination with poly(lactide-co-glycolide acid) (PLGA) as a biodegradable drug delivery system. Hence, non-absorbable monofilament and multifilament sutures were coated with solutions containing different amounts and ratios of totarol and PLGA, resulting in a smooth, crystalline coating. Using an agar diffusion test (ADT), it became evident that the PLGA/totarol-coated sutures inhibited the growth of Staphylococcus aureus over a period of 15 days. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the coated sutures were not cytotoxic to murine fibroblasts. Overall, the data indicates that our innovative, biodegradable suture coating has the potential to reduce the risk of SSIs and postoperative biofilm-formation on suture material without adverse effects on tissue.

Suture thread check test for detection of surgical site contamination: a prospective study

BACKGROUND

Surgical site infection (SSI) is a common complication of surgical procedures.

AIM

Our study aimed at investigating a new method based on assessment of suture thread colonization to identify patients developing an SSI.

MATERIALS AND METHODS

We prospectively enrolled 119 patients undergoing elective surgery. For each patient, a synthetic absorbable thread in Lactomer 9-1 (Polisorb Gauge 2) inserted in the surgical site at the end of surgery was sent to the microbiology laboratory after 48 h to assess colonization of its inner tract.

RESULTS

Forty (33.6% of cases) patients had a colonized thread. Antibiotic prophylaxis was administered to 66 of 79 patients who did not display a colonized thread and to 20 of the 40 patients with a colonized thread (83.5% versus 50%, respectively, P = 0.0002). An SSI was observed only in patients with a colonized thread (10% versus 0, P = 0.02). The microorganisms identified in colonized threads were the same identified in SSIs.

CONCLUSIONS

Since an SSI was found only in patients with colonized threads, the method described here may be valuable for identifying patients developing an SSI. Moreover, the method can also be useful for targeting efficient antibiotic therapy to the culprit microorganisms.

Application of Materials as Medical Devices with Localized Drug Delivery Capabilities for Enhanced Wound Repair

The plentiful assortment of natural and synthetic materials can be leveraged to accommodate diverse wound types, as well as different stages of the healing process. An ideal material is envisioned to promote tissue repair with minimal inconvenience for patients. Traditional materials employed in the clinical setting often invoke secondary complications, such as infection, pain, foreign body reaction, and chronic inflammation. This review surveys the repertoire of surgical sutures, wound dressings, surgical glues, orthopedic fixation devices and bone fillers with drug eluting capabilities. It highlights the various techniques developed to effectively incorporate drugs into the selected material or blend of materials for both soft and hard tissue repair. The mechanical and chemical attributes of the resultant materials are also discussed, along with their biological outcomes in vitro and/or in vivo. Perspectives and challenges regarding future research endeavors are also delineated for next-generation wound repair materials.