Cathodic voltage-controlled electrical stimulation of titanium for prevention of methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii biofilm infections

The biofilm removal effect and osteogenic potential on the titanium surface by electrolytic cleaning: An in vitro comparison of electrolytic parameters and five techniques

OBJECTIVES

To determine the optimal current and time of electrolytic cleaning (EC), compare its biofilm removal effect with generic treatments and evaluate the influence of EC to surface characteristics and osteogenic potential of SLA titanium (Ti) discs.

MATERIALS AND METHODS

The six-species biofilm-covered Ti discs were placed as cathodes in physiologic saline and subjected to various current and time treatments. The residual biofilms were evaluated to determine the optimal parameters. The contaminated Ti discs were randomized and treated by rotating Ti brush; ultrasonic-scaling with metal tips; ultrasonic-scaling with PEEK tips; air-polishing and EC. The residual biofilms were compared using a lipopolysaccharide kit (LPS), scanning electron microscope (SEM), confocal laser scanning microscopy and colony-forming unit counting. Non-contaminated Ti discs were treated and characterized. The bone marrow mesenchymal stem cells (BMSCs) were cultured on treated non-contaminated Ti discs. The adhesion, proliferation, alkaline phosphatase (ALP) activity and osteocalcin level of BMSCs were assessed.

RESULTS

The parameters at 0.6A5min were considered optimal. For LPS and SEM, EC promoted a significantly greater biofilm removal than the other groups. There were no changes in the Ti discs' colour, topography, roughness and chemical elements after EC, and the electrolysis-treated Ti discs obtained a super-hydrophilic surface. EC positively impacted the proliferation and ALP activity of BMSCs, surpassing the efficacy of alternative treatments.

CONCLUSIONS

EC achieves a near-complete eradication of contaminants on the SLA surface, causes no surface damage with improved hydrophilicity, and promotes the early osteogenic response of BMSCs, which makes it a promising treatment for peri-implantitis.

Cathodic voltage-controlled electrical stimulation and betadine decontaminate nosocomial pathogens from implant surfaces

Periprosthetic joint infection (PJI) after total joint arthroplasty is a major concern requiring multiple surgeries and antibiotic interventions. Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli are the predominant causes of these infections. Due to biofilm formation, antibiotic treatment for patients with PJI can prolong resistance, further complicating the use of current treatments. Previous research has shown that cathodic voltage-controlled electrical stimulation (CVCES) is an effective technique to prevent/treat implant-associated biofilm infections on titanium (Ti) surfaces. This study thus evaluated the efficacy of CVCES via the use of 10% betadine alone and in combination with CVCES to eradicate lab-grown biofilms on cemented and cementless cobalt-chromium (CoCr) and Ti surfaces. CVCES treatment alone for 24 hours demonstrated no detectable CFU for E. coli and P. aeruginosa biofilms on cementless CoCr implants. In the presence of cement, E. coli biofilms had 106 CFUs/implant remaining after CVCES treatment alone; however, P. aeruginosa biofilms on cemented implants were reduced to below detectable limits. The use of 10% betadine treatment for 3 minutes followed by 24-hour CVCES treatment brought CFU levels to below detectable limits in E. coli and P. aeruginosa. The same was true for S. aureus biofilms on cementless patellofemoral implants as well as femoral and tibial implants. These treatment methods were not sufficient for eradication of S. aureus biofilms on cemented implants. These results suggest that CVCES alone and CVCES with 10% betadine are effective approaches to treating biofilms formed by certain bacterial species potentially leading to the treatment of PJI.IMPORTANCEPeriprosthetic joint infections (PJIs) are problematic due to requiring multiple surgeries and antibiotic therapies that are responsible for increased patient morbidity and healthcare costs. These infections become resistant to antibiotic treatment due to the formation of biofilms on the orthopedic surfaces. Cathodic voltage-controlled electrical stimulation (CVCES) has previously been shown to be an effective technique to prevent and treat biofilm infections on different surfaces. This study shows that CVCES can increase the efficacy of 10% betadine irrigation used in debridement, antibiotics, and implant retention by 99.9% and clear infection to below detection limits. PJI treatments are at times limited, and CVCES could be a promising technology to improve patient outcomes.

The Mark Coventry Award: PhotothermAA Gel Combined With Debridement, Antibiotics, and Implant Retention Significantly Decreases Implant Biofilm Burden and Soft-Tissue Infection in a Rabbit Model of Knee Periprosthetic Joint Infection

BACKGROUND

Chronic periprosthetic joint infection (PJI) is a major complication of total joint arthroplasty. The underlying pathogenesis often involves the formation of bacterial biofilm that protects the pathogen from both host immune responses and antibiotics. The gold standard treatment requires implant removal, a procedure that carries associated morbidity and mortality risks. Strategies to preserve the implant while treating PJI are desperately needed. Our group has developed an anti-biofilm treatment, PhotothermAA gel, which has shown complete eradication of 2-week-old mature biofilm in vitro. In this study, we tested the anti-biofilm efficacy and safety of PhotothermAA in vivo when combined with debridement, antibiotics and implant retention (DAIR) in a rabbit model of knee PJI.

METHODS

New Zealand white rabbits (n = 21) underwent knee joint arthrotomy, titanium tibial implant insertion, and inoculation with Xen36 (bioluminescent Staphylococcus aureus) after capsule closure. At 2 weeks, rabbits underwent sham surgery (n = 6), DAIR (n = 6), or PhotothermAA with DAIR (n = 9) and were sacrificed 2 weeks later to measure implant biofilm burden, soft-tissue infection, and tissue necrosis.

RESULTS

The combination of anti-biofilm PhotothermAA with DAIR significantly decreased implant biofilm coverage via scanning electron microscopy compared to DAIR alone (1.8 versus 81.0%; P < .0001). Periprosthetic soft-tissue cultures were significantly decreased in the PhotothermAA with DAIR treatment group (log reduction: Sham 1.6, DAIR 2.0, combination 5.6; P < .0001). Treatment-associated necrosis was absent via gross histology of tissue adjacent to the treatment area (P = .715).

CONCLUSIONS

The addition of an anti-biofilm solution like PhotothermAA as a supplement to current treatments that allow implant retention may prove useful in PJI treatment.

In vitro and in vivo assessment of extended duration cathodic voltage-controlled electrical stimulation for treatment of orthopedic implant-associated infections

Effective treatment of orthopedic implant-associated infections (IAIs) remains a clinical challenge. The in vitro and in vivo studies presented herein evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) to titanium implants inoculated with preformed bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that combining vancomycin therapy (500 µg/mL) with application of CVCES at -1.75 V (all voltages are with respect to Ag/AgCl unless otherwise stated) for 24 h resulted in 99.98% reduction in the coupon-associated MRSA colony-forming units (CFUs) (3.38 × 103 vs. 2.14 × 107 CFU/mL, p < 0.001) and a 99.97% reduction in the planktonic CFU (4.04 × 104 vs. 1.26 × 108 CFU/mL, p < 0.001) as compared with the no treatment control samples. The in vivo studies utilized a rodent model of MRSA IAIs and showed a combination of vancomycin therapy (150 mg/kg twice daily) with CVCES of -1.75 V for 24 h had significant reductions in the implant associated CFU (1.42 × 101 vs. 1.2 × 106 CFU/mL, p < 0.003) and bone CFU (5.29 × 101 vs. 4.48 × 106 CFU/mL, p < 0.003) as compared with the untreated control animals. Importantly, the combined 24 h CVCES and antibiotic treatments resulted in no implant-associated MRSA CFU enumerated in 83% of the animals (five out of six animals) and no bone-associated MRSA CFU enumerated in 50% of the animals (three out of six animals). Overall, the outcomes of this study have shown that extended duration CVCES therapy is an effective adjunctive therapy to eradicate IAIs.

In Situ Polymerization of Methylene Blue on Bacterial Cellulose for Photodynamic/Photoelectricity Synergistic Inhibition of Bacterial Biofilm Formation

In the context of long-term antimicrobial treatment, the emergence of bacterial resistance poses a significant challenge. Therefore, there is a pressing need to develop novel antimicrobial materials and methods that can effectively and safely combat microbial infections. This study focuses on the synthesis of bacterial cellulose-polymethylene blue (BC-PMB) with integrated photodynamic and photoelectric antimicrobial properties. The polymerization of methyl blue (MB) onto bacterial celluloses (BC) was achieved, and through comprehensive computational analyses using density functional theory (DFT) and molecular dynamics simulations, it was confirmed that this polymerization greatly enhanced the binding efficiency between methylene blue and BC. Additionally, polymethylene blue (PMB) exhibited superior photoexcitation efficiency and conductivity compared to its precursor. When BC-PMB was exposed to a 30 mW 660 nm light source for 30 min, the material demonstrated a remarkable antimicrobial efficacy of 93.99% against Escherichia coli and 98.58% against Staphylococcus aureus. Furthermore, the synergistic effect of photodynamic and photoelectric antimicrobial mechanisms exhibited long-term inhibitory capabilities against bacterial biofilms.

Effect of Enterococcus faecalis Biofilm on Corrosion Kinetics in Titanium Grade 4 Alloys with Different Surface Treatments

E. faecalis has been associated with bacteremia, sepsis, and bacterial endocarditis and peri-implantitis. This microorganism can remain in the alveolus even after extraction of the root remnant. This study aimed to evaluate the corrosion on different surfaces of commercially pure titanium (Ti) grade 4 (Ticp-G4) as a function of the bacterial biofilm effect of Enterococcus faecalis. A total of 57 discs were randomly divided according to their surface finish (n = 19). For microbiological analysis (n = 9), the discs were placed in 12-well plates containing E. faecalis culture and incubated at 37 °C for 7 days. The results show that for the intergroup analysis, considering the "electrolyte" factor, there was a difference between the groups. There was greater biofilm formation for the D.A.Zir group, with greater electrochemical exchange for Biofilm, and the presence of biofilm favored greater electrochemical exchange with the medium.

Physical Approaches to Prevent and Treat Bacterial Biofilm

Prosthetic joint infection (PJI) presents several clinical challenges. This is in large part due to the formation of biofilm which can make infection eradication exceedingly difficult. Following an extensive literature search, this review surveys a variety of non-pharmacological methods of preventing and/or treating biofilm within the body and how they could be utilized in the treatment of PJI. Special attention has been paid to physical strategies such as heat, light, sound, and electromagnetic energy, and their uses in biofilm treatment. Though these methods are still under study, they offer a potential means to reduce the morbidity and financial burden related to multiple stage revisions and prolonged systemic antibiotic courses that make up the current gold standard in PJI treatment. Given that these options are still in the early stages of development and offer their own strengths and weaknesses, this review offers an assessment of each method, the progress made on each, and allows for comparison of methods with discussion of future challenges to their implementation in a clinical setting.

Programmable Electrochemical Stimulation on a Large-Scale CMOS Microelectrode Array

In this paper we present spatio-temporally controlled electrochemical stimulation of aqueous samples using an integrated CMOS microelectrode array with 131,072 pixels. We demonstrate programmable gold electrodeposition in arbitrary spatial patterns, controllable electrolysis to produce microscale hydrogen bubbles, and spatially targeted electrochemical pH modulation. Dense spatially-addressable electrochemical stimulation is important for a wide range of bioelectronics applications.

Current treatments for biofilm-associated periprosthetic joint infection and new potential strategies

Periprosthetic joint infection (PJI) remains a devastating complication after total joint arthroplasty. Bacteria involved in these infections are notorious for adhering to foreign implanted surfaces and generating a biofilm matrix. These biofilms protect the bacteria from antibiotic treatment and the immune system making eradication difficult. Current treatment strategies including debridement, antibiotics, and implant retention, and one- and two-stage revisions still present a relatively high overall failure rate. One of the main shortcomings that has been associated with this high failure rate is the lack of a robust approach to treating bacterial biofilm. Therefore, in this review, we will highlight new strategies that have the potential to combat PJI by targeting biofilm integrity, therefore giving antibiotics and the immune system access to the internal network of the biofilm structure. This combination antibiofilm/antibiotic therapy may be a new strategy for PJI treatment while promoting implant retention.

A healing promoting wound dressing with tailor-made antibacterial potency employing piezocatalytic processes in multi-functional nanocomposites

Developing a novel antibiotics-free antibacterial strategy is essential for minimizing bacterial resistance. Materials that not only kill bacteria but also promote tissue healing are especially challenging to achieve. Inspired by chemical conversion processes in living organisms, we develop a piezoelectrically active antibacterial device that converts ambient O₂ and H₂O to ROS by piezocatalytic processes. The device is achieved by mounting nanoscopic polypyrrole/carbon nanotube catalyst multilayers onto piezoelectric-dielectric films. Under stimuli by a hand-held massage device, the sterilizing rates for S. aureus and E. coli reach 84.11% and 94.85% after 10 minutes of operation, respectively. The antibacterial substrate at the same time preserves and releases drugs and presents negligible cytotoxicity. Animal experiments demonstrate that daily treatment for 10 minutes using the device effectively accelerates the healing of infected wounds on the backs of mice, promoting hair follicle generation and collagen deposition. We believe that this report provides a novel design approach for antibacterial strategies in medical treatment.

Ionic Silver and Electrical Treatment for Susceptibility and Disinfection of Escherichia coli Biofilm-Contaminated Titanium Surface

In this work, surface disinfection and biofilm susceptibility were investigated by applying ionic silver of 0.4–1.6 µg/mL and cathodic voltage-controlled electrical treatment of 1.8 V and a current of 30 mA to Escherichia coli (E. coli) ATCC 25922 biofilm-contaminated titanium substrates. Herein, it is evident that the treatment exhibited the potential use to enhance the susceptibility of bacterial biofilms for surface disinfection. In vitro studies have demonstrated that the ionic silver treatment of 60 min significantly increased the logarithmic reduction (LR) of bacterial populations on disinfectant-treated substrates and the electrical treatment enhanced the silver susceptibility of E. coli biofilms. The LR values after the ionic silver treatments and the electric-enhanced silver treatments were in the ranges of 1.94–2.25 and 2.10–2.73, respectively. The treatment was also associated with morphological changes in silver-treated E. coli cells and biofilm-contaminated titanium surfaces. Nevertheless, the treatments showed no cytotoxic effects on the L929 mouse skin fibroblast cell line and only a slight decrease in pH was observed during the electrical polarization of titanium substrate.

Development of an anti-infective coating on the surface of intraosseous implants responsive to enzymes and bacteria

Background

Bacterial proliferation on the endosseous implants surface presents a new threat to the using of the bone implants. Unfortunately, there is no effective constructed antibacterial coating which is bacterial anti-adhesion substrate-independent or have long-term biofilm inhibition functions.

Methods

Drug release effect was tested in Chymotrypsin (CMS) solution and S. aureus. We used bacterial inhibition rate assays and protein leakage experiment to analyze the in vitro antibacterial effect of (Montmorillonite/Poly-l-lysine-Chlorhexidine)₁₀ [(MMT/PLL-CHX)₁₀] multilayer film. We used the CCK-8 assay to analyze the effect of (MMT/PLL-CHX)₁₀ multilayer films on the growth and proliferation of rat osteoblasts. Rat orthopaedic implant-related infections model was constructed to test the antimicrobial activity effect of (MMT/PLL-CHX)₁₀ multilayer films in vivo.

Results

In this study, the (MMT/PLL-CHX)₁₀ multilayer films structure were progressively degraded and showed well concentration-dependent degradation characteristics following incubation with Staphylococcus aureus and CMS solution. Bacterial inhibition rate assays and protein leakage experiment showed high levels of bactericidal activity. While the CCK-8 analysis proved that the (MMT/PLL-CHX)₁₀ multilayer films possess perfect biocompatibility. It is somewhat encouraging that in the in vivo antibacterial tests, the K-wires coated with (MMT/PLL-CHX)₁₀ multilayer films showed lower infections incidence and inflammation than the unmodified group, and all parameters are close to SHAM group.

Conclusion

(MMT/PLL-CHX)₁₀ multilayer films provides a potential therapeutic method for orthopaedic implant-related infections.

Dual response of osteoblast activity and antibacterial properties of polarized strontium substituted hydroxyapatite-Barium strontium titanate composites with controlled strontium substitution

To mimic the electrical properties of natural bone, controlled strontium substitution of both hydroxyapatite and ferroelectric barium titanate were achieved by mixing in the ratio 30:70 by weight. The composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy to investigate the phase composition and microstructure of the composites. Unpolarized and polarized strontium hydroxyapatite (SrHA)-barium strontium titanate (BST) composites with controlled degree of Sr substitution were examined, including 5SrHA-5BST (5% Sr substitution in both components) and 10SrHA-10BST composites. The 10SrHA-10BST composite showed a higher osteoblast activity, as observed from the cell viability studies performed using CCK-8 assay. The polarized composites showed promise against Staphylococcus aureus bacteria by minimizing the adhesion and growth of bacteria, as compared with their unpolarized counterparts. The polarized 10SrHA-10BST was found to be superior than all other composites. As a result, the approach of polarization of SrHA-BST composites has been found to be an effective bone substitute material in controlled enhancement of osteoblast growth with simultaneous reduction of bacterial infection.

The Chemical and Biological Properties of Nanohydroxyapatite Coatings with Antibacterial Nanometals, Obtained in the Electrophoretic Process on the Ti13Zr13Nb Alloy

The risk of an early inflammation after implantation surgery of titanium implants has caused the development of different antimicrobial measures. The present research is aimed at characterizing the effects of nanosilver and nanocopper dispersed in the nanohydroxyapatite coatings, deposited on the Ti13Zr13Nb alloy, and on the chemical and biological properties of the coatings. The one-stage deposition process was performed by the electrophoretic method at different contents of nanomaterials in suspension. The surface topography of the coatings was examined with scanning electron microscopy. The wettability was expressed as the water contact angle. The corrosion behavior was characterized by the potentiodynamic technique. The release rate of copper and silver into the simulated body fluid was investigated by atomic absorption spectrometry. The antibacterial efficiency was evaluated as the survivability and adhesion of the bacteria and the growth of the biofilm. The cytotoxicity was assessed for osteoblasts. The results demonstrate that silver and copper increase the corrosion resistance and hydrophilicity. Both elements together effectively kill bacteria and inhibit biofilm growth but appear to be toxic for osteoblasts. The obtained results show that the nanohydroxyapatite coatings doped with nanosilver and nanocopper in a one-stage electrophoretic process can be valuable for antibacterial coatings.

Orthopaedic osseointegration: Implantology and future directions

Osseointegration (OI) is the direct anchorage of a metal implant into bone, allowing for the connection of an external prosthesis to the skeleton. Osseointegration was first discovered in the 1960s based on the microscopic analysis of titanium implant placed into host bone. New bone was observed to attach directly to the metal surface. Following clinical investigations into dentistry applications, OI was adapted to treat extremity amputations. These bone anchored implants, which penetrate the skin and soft tissues, eliminate many of the challenges of conventional prosthetic sockets, such as poor fit and suspension, skin breakdown, and pain. Osseointegrated implants show promise to improve prosthesis use, pain, and function for amputees. The successful process of transcutaneous metal integration into host bone requires three synergistic systems: the host bone, the metal implant, and the skin-implant interface. All three systems must be optimized for successful incorporation and longevity of the implant. Osseointegration begins during surgical implantation of the metal components through a complex interplay of cellular mechanisms. While implants can vary in design-including the original screw, press fit implants, and compressive osseointegration-they face common challenges to successful integration and maintenance of fixation within the host bone. Overcoming these challenges requires the understanding of the complex interactions between each element of OI. This review outlines (a) the basic components of OI, (b) the science behind both the bone-implant and the skin-implant interfaces, (c) the current challenges of OI, and (d) future opportunities within the field.

Ultrastructure imaging of Pseudomonas aeruginosa lawn biofilms and eradication of the tobramycin-resistant variants under in vitro electroceutical treatment

Electrochemically generated bactericidal compounds have been shown to eradicate bacterial lawn biofilms through electroceutical treatment. However, the ultrastructure of biofilms exposed to these species has not been studied. Moreover, it is unknown if the efficacy of electroceutical treatment extends to antibiotic-resistant variants that emerge in lawn biofilms after antibiotic treatment. In this report, the efficacy of the in vitro electroceutical treatment of Pseudomonas aeruginosa biofilms is demonstrated both at room temperature and in an incubator, with a ~4 log decrease (p < 0.01) in the biofilm viability observed over the anode at both conditions. The ultrastructure changes in the lawn biofilms imaged using transmission electron microscopy demonstrate significant bacterial cell damage over the anode after 24 h of electroceutical treatment. A mix of both damaged and undamaged cells was observed over the cathode. Finally, both eradication and prevention of the emergence of tobramycin-resistant variants were demonstrated by combining antibiotic treatment with electroceutical treatment on the lawn biofilms.

Electroactive 3D Printed Scaffolds Based on Percolated Composites of Polycaprolactone With Thermally Reduced Graphene Oxide for Antibacterial and Tissue Engineering Applications

Applying electrical stimulation (ES) could affect different cellular mechanisms, thereby producing a bactericidal effect and an increase in human cell viability. Despite its relevance, this bioelectric effect has been barely reported in percolated conductive biopolymers. In this context, electroactive polycaprolactone (PCL) scaffolds with conductive Thermally Reduced Graphene Oxide (TrGO) nanoparticles were obtained by a 3D printing method. Under direct current (DC) along the percolated scaffolds, a strong antibacterial effect was observed, which completely eradicated S. aureus on the surface of scaffolds. Notably, the same ES regime also produced a four-fold increase in the viability of human mesenchymal stem cells attached to the 3D conductive PCL/TrGO scaffold compared with the pure PCL scaffold. These results have widened the design of novel electroactive composite polymers that could both eliminate the bacteria adhered to the scaffold and increase human cell viability, which have great potential in tissue engineering applications.

The state of the art of osseointegration for limb prosthesis

Osseointegration (OI) is the direct attachment of bone onto a titanium implant. Recently, the term is used to describe "transdermal" implants that allow an external prosthesis to be connected directly to the skeleton. This technology eliminates the challenges of conventional socket-based prostheses, such as skin breakdown and poor fit, which are common in patients with major extremity amputations. Osseointegration patients demonstrate encouraging improvements in quality of life and function. Patients report improvement in prosthetic use, prosthetic mobility, global health, and pain reduction on a variety of clinical assessment tools. Various implants have been developed for osseointegration for amputees. These implants use a variety of fixation strategies and surface augments to allow for successful integration into the host bone. Regardless of design, all OI implants face similar challenges, particularly infections. Other challenges include the inability to determine when integration has occurred and the inability to detect loss of integration. These challenges may be met by incorporating sensing systems into the implants. The percutaneous nature of the metal devices can be leveraged so that internal sensors need not be wireless, and can be interrogated by external monitoring systems, thus providing crucial, real-time information about the state of the implant. The purpose of this review is to (1) review the basic science behind osseointegration, (2) provide an overview of current implants, practice patterns, and clinical outcomes, and (3) preview sensor technologies which may prove useful in future generations of transdermal orthopaedic implants.

Electrochemical methods to enhance osseointegrated prostheses

Osseointegrated (OI) prosthetic limbs have been shown to provide an advantageous treatment option for amputees. In order for the OI prosthesis to be successful, the titanium implant must rapidly achieve and maintain proper integration with the bone tissue and remain free of infection. Electrochemical methods can be utilized to control and/or monitor the interfacial microenvironment where the titanium implant interacts with the biological system (host bone tissue or bacteria). This review will summarize the current understanding of how electrochemical modalities can influence bone tissue and bacteria with specific emphasis on applications where the metallic prosthesis itself can be utilized directly as a stimulating electrode for enhanced osseointegration and infection control. In addition, a summary of electrochemical impedance sensing techniques that could be used to potentially assess osseointegration and infection status of the metallic prosthesis is presented.

Antibiotics Enhance Prevention and Eradication Efficacy of Cathodic-Voltage-Controlled Electrical Stimulation against Titanium-Associated Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa Biofilms

Periprosthetic joint infections (PJIs) develop clinically in the presence of antibiotic therapies and are responsible for increased patient morbidity and rising health care costs. Many of these infections involve bacterial biofilm formation on orthopedic hardware, and it has been well established that these biofilms are refractory to most antibiotic treatments. Recent studies have focused on novel methods to prevent and eradicate infection. Cathodic-voltage-controlled electrical stimulation (CVCES) has previously been shown to be effective as a method for prevention and eradication of Gram-positive and Gram-negative infections. The present study revealed that the utility of CVCES for prevention and eradication of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa is enhanced in the presence of clinically relevant antibiotics. The synergistic effects of CVCES and antibiotics are effective in a magnitude-dependent manner. The results of this study indicate a promising alternative method to current PJI mitigation techniques.

Periprosthetic joint infection (PJI) develops clinically, even with antibiotic treatment, and methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are predominant causes of these infections. Due to biofilm formation, antibiotic treatment for patients with PJI can perpetuate resistance, further complicating the use of noninvasive treatments. This study evaluated cathodic-voltage-controlled electrical stimulation (CVCES) of titanium, in combination with a clinically relevant antibiotic, to synergistically prevent MRSA and P. aeruginosa PJIs by inhibiting bacterial adherence or as a treatment for eradicating established biofilms. CVCES of −1.0 V, −1.5 V, or −1.8 V (versus Ag/AgCl), with or without vancomycin for MRSA or gentamicin for P. aeruginosa, was applied to sterile titanium incubated with cultures to evaluate prevention of attachment or eradication of preestablished biofilms. Treatments were 24 h long and included open-circuit potential controls, antibiotic alone, CVCES, and CVCES plus antibiotic. Biofilm-associated and planktonic CFU were enumerated. In general, CVCES at −1.8 V alone or with antibiotic completely eradicated biofilm-associated CFU for both strains, and these parameters were also highly effective against planktonic bacteria, resulting in a >6-log reduction in MRSA and no detectable planktonic P. aeruginosa. All CFU were reduced ∼3 to 5 logs from controls for prevention CVCES plus antibiotics at −1.0 V and −1.5 V against MRSA. Remarkably, there were no detectable P. aeruginosa CFU following prevention CVCES at −1.0 V or −1.5 V with gentamicin. Our results suggest that CVCES in combination with antibiotics may be an effective approach for prevention and treatment of PJI.

IMPORTANCE Periprosthetic joint infections (PJIs) develop clinically in the presence of antibiotic therapies and are responsible for increased patient morbidity and rising health care costs. Many of these infections involve bacterial biofilm formation on orthopedic hardware, and it has been well established that these biofilms are refractory to most antibiotic treatments. Recent studies have focused on novel methods to prevent and eradicate infection. Cathodic-voltage-controlled electrical stimulation (CVCES) has previously been shown to be effective as a method for prevention and eradication of Gram-positive and Gram-negative infections. The present study revealed that the utility of CVCES for prevention and eradication of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa is enhanced in the presence of clinically relevant antibiotics. The synergistic effects of CVCES and antibiotics are effective in a magnitude-dependent manner. The results of this study indicate a promising alternative method to current PJI mitigation techniques.

Hypochlorous-Acid-Generating Electrochemical Scaffold for Treatment of Wound Biofilms

Biofilm formation causes prolonged wound infections due to the dense biofilm structure, differential gene regulation to combat stress, and production of extracellular polymeric substances. Acinetobacter baumannii, Staphylococcus aureus, and Pseudomonas aeruginosa are three difficult-to-treat biofilm-forming bacteria frequently found in wound infections. This work describes a novel wound dressing in the form of an electrochemical scaffold (e-scaffold) that generates controlled, low concentrations of hypochlorous acid (HOCl) suitable for killing biofilm communities without substantially damaging host tissue. Production of HOCl near the e-scaffold surface was verified by measuring its concentration using needle-type microelectrodes. E-scaffolds producing 17, 10 and 7 mM HOCl completely eradicated S. aureus, A. baumannii, and P. aeruginosa biofilms after 3 hours, 2 hours, and 1 hour, respectively. Cytotoxicity and histopathological assessment showed no discernible harm to host tissues when e-scaffolds were applied to explant biofilms. The described strategy may provide a novel antibiotic-free strategy for treating persistent biofilm-associated infections, such as wound infections.

The antibacterial effect of potassium-sodium niobate ceramics based on controlling piezoelectric properties

The implant infection is one of the most serious postsurgical complications of medical device implantation. Therefore, the development of biocompatible materials with improved antibacterial properties is of great importance. It might be a new insight to apply the intrinsic electrical properties of biomaterials to solve this problem. Here, potassium-sodium niobate piezoceramics (K_0.5Na_0.5NbO₃, KNN) with different piezoelectric constants were prepared, and the microstructures and piezoelectric properties of these piezoceramics were evaluated. Moreover, the antibacterial effect and biocompatibility of these piezoceramics were assayed. Results showed that these piezoceramics were able to decrease the colonies of bacteria staphylococcus aureus (S. aureus), favor the rat bone marrow mesenchymal stem cells (rBMSCs) proliferation and promote the cell adhesion and spreading. The above effects were found closely related to the surface positive charges of the piezoceramics, and the sample bearing the most positive charges on its surface (sample 80KNN) had the best performance in both antibacterial effect and biocompatibility. Based on our work, it is feasible to develop biocompatible antibacterial materials by controlling piezoelectric properties.