In vitro activities of daptomycin-, vancomycin-, and teicoplanin-loaded polymethylmethacrylate against methicillin-susceptible, methicillin-resistant, and vancomycin-intermediate strains of Staphylococcus aureus

Pharmacokinetic study of local and systemic gentamicin concentrations after subcutaneous implantation of a gentamicin-impregnated collagen sponge in dogs

This study evaluated the pharmacokinetics of commercial gentamicin-impregnated collagen sponges (GICS) applied subcutaneously in dogs. In six healthy beagles, an 11 ×6 cm subcutaneous pocket was created, a folded 10×10 cm GICS was inserted, and saline was injected to mimic a seroma. Wound fluid samples were aspirated, and the gentamicin concentration was determined. Simultaneously, blood samples were collected to evaluate the corresponding systemic gentamicin concentration. All samples were collected before and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, 24, 36, 48, 72, 96, 120, and 168 hours after GICS placement. The local Cmax of gentamicin was reached after 0.5 hours (range, 0.5-1.0 hours) post-implantation in 5/6 dogs at a median concentration of 2053.3 µg/mL (range, 918.0-2791.9 µg/mL). Whitin 24 hours, the local concentration dropped below the MIC for Staphylococcus sp. (4 µg/mL) in 5/6 dogs. Plasma Cmax was achieved at a median of 1.2 hours post-implantation (range, 1.0-2.0 hours) and reached a median concentration of 10.3 µg/mL (range, 8.8-18.03 µg/mL). After 6 hours, the gentamicin concentration in the plasma was below 4 µg/mL in all dogs. The GICS provided a high local concentration of gentamicin in a short time with a local Cmax:MIC ratio of 513:1, largely sufficient to eliminate susceptible bacteria, including methicillin-resistant Staphylococcus pseudintermedius (MRSP) and Pseudomonas sp., in a clinical setting. The repeated administration of saline in the present study seemed to have induced a quicker gentamicin release from the GICS than described in previous studies that typically dealt with "drier" wounds.

High and Low Dosage of Vancomycin in Polymethylmethacrylate Cements: Efficacy and Mechanical Properties

INTRODUCTION

Prosthetic joint infections (PJIs) are difficult to treat and represent a significant burden to the healthcare system. Two-stage revision surgery with placement of an antibiotic-loaded cement spacer is currently the gold standard for treatment in the United States for late-onset infections. We evaluate the efficacy of varying doses of vancomycin added to antibiotic-containing acrylic cement spacers and discuss the biomechanical and antimicrobial properties of using high versus low doses of vancomycin in cement spacers in the hip and knee.

MATERIALS AND METHODS

Commercially available Copal cement containing either gentamicin and clindamycin (G + C) or gentamicin and vancomycin (G + V) was prepared with the manual addition of low (2 g) and high (6 g) doses of vancomycin. In vitro mechanical testing was then carried out according to ISO 5833 and DIN 53435, as well as inhibition zone assays against common PJI pathogens. Additionally, inhibition zone assays were conducted on two commercially available prefabricated spacers containing gentamicin: Copal Exchange G and Cemex Spacer-K.

RESULTS

In biomechanical testing, Copal G + V with the addition of 6 g of vancomycin failed to meet the ISO standard. Copal G + C and Copal G + V with low and high dosages of vancomycin were all effective against the tested pathogens and displayed constant efficacy for a duration of 42 days. High doses of vancomycin showed significantly lower mechanical stability. Moreover, Copal Exchange G showed significantly larger inhibition zones across 42 days.

DISCUSSION

While higher concentrations of vancomycin appear to improve the antimicrobial efficacy of cement, they also reduce its mechanical stability. Despite its smoother surface, the Copal Exchange G spacer exhibits large inhibition zones after 1 day and maintains consistently large inhibition zones over 6 weeks. Thus, it may be preferred for use in two-stage revision surgery.

CONCLUSION

Copal Exchange G is more effective than Cemex Spacer K against S. aureus and E. coli. The manual addition of vancomycin to cement containing double antibiotics is very effective. The influence on ISO compression is low, the ISO bending modulus is increased, and ISO bending, DIN bending, and DIN impact, are reduced.

Antimicrobial Regimens in Cement Spacers for Periprosthetic Joint Infections: A Critical Review

Antibiotic-loaded cement spacers (ALCSs) are essential for treating periprosthetic joint infections (PJIs) by providing mechanical support and local antibiotic delivery. The purpose of this review is to comprehensively examine the various types of spacers utilised in the management of periprosthetic joint infections (PJIs), including both static and articulating variants and to analyse the fundamental principles underlying spacer use, their clinical benefits, the selection and administration of antimicrobial agents, appropriate dosages, and potential adverse effects. Articulating spacers, which allow joint mobility, often yield better outcomes than static ones. Spacer pharmacokinetics are vital for maintaining therapeutic antibiotic levels, influenced by cement porosity, mixing techniques, and the contact area. Antibiotic choice depends on heat stability, solubility, and impact on cement's mechanical properties. Mechanical properties are crucial, as spacers must withstand physical stresses, with antibiotics potentially affecting these properties. Complications, such as tissue damage and systemic toxicity, are discussed, along with mitigation strategies. Future advancements include surface modifications and novel carriers to enhance biofilm management and infection control.

Retention of Antibiotic Cement Delivery Implants in Orthopedic Infection Associated With United Fractures Does Not Increase Recurrence Risk

OBJECTIVES

To evaluate whether retention of antibiotic cement delivery devices after resolution of orthopaedic infection is associated with recurrence.

METHODS

DESIGN

Retrospective cohort.

SETTING

Academic medical center.

PATIENT SELECTION CRITERIA

Patients with a fracture definitively treated with internal fixation that went on to unite and develop a confirmed fracture-related infection or osteomyelitis after a remote fracture surgery and had implantation of antibiotic-impregnated cement for infection management.

OUTCOME MEASURES AND COMPARISONS

Patients were divided into whom the antibiotic implants were retained (Retained Cohort) and whom the antibiotic implants were removed (Removed Cohort). Outcome measures included clinical infection resolution, infection recurrence, time to resolution of infection signs, symptoms and laboratory values, reoperation and readmission rates, and need for soft tissue coverage (local flap vs. free tissue transfer) because of recurrence.

RESULTS

Of 98 patients treated for fracture-related infection in united fractures or osteomyelitis after a remote fracture surgery, 39 (39.8%) underwent implantation of antibiotic-impregnated cement delivery devices: 21 (21.4%) beads, 7 (7.1%) rods, and 11 (11.2%) blocks. Twenty patients (51.3%) comprised the Retained Cohort and 19 patients (48.7%) comprised the Removed Cohort. There were few differences in demographics ([American Society of Anesthesiology Score, P = 0.026] and [diabetes, P = 0.047]), infection location, and pathogenic profiles. The cohorts demonstrated no difference in eventual resolution of infection (100% in the Retained Cohort, 95% in the Removed Cohort, P = 0.487) and experienced similar time to clinical infection resolution, based on signs, symptoms, and laboratory values ( P = 0.360). There was no difference in incidence of subsequent infection recurrence after clinical infection resolution (1 recurrence Retained vs. 2 recurrences Removed, P = 0.605) for those considered "cured." Compared with the Retained Cohort, the Removed Cohort underwent more reoperations (0.40 vs. 1.84 reoperations, P < 0.001) and admissions after implantation ( P < 0.001).

CONCLUSIONS

Retention of antibiotic-impregnated cement delivery devices in patients with orthopaedic infection after fractured bones that have healed was not associated with infection recurrence. Additional surgical intervention with the sole purpose of removing antibiotic delivery devices may not be warranted.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Utilization of Antibiotic Bone Cement in Spine Surgery: Pearls, Techniques, and Case Review

Vertebral osteomyelitis (VO) encompasses a spectrum of spinal infections ranging from isolated mild vertebral osteomyelitis to severe diffuse infection with associated epidural abscess and fracture. Although patients can often be treated with an initial course of intravenous antibiotics, surgery is sometimes required in patients with sepsis, spinal instability, neurological compromise, or failed medical treatment. Antibiotic bone cement (ABC) has been widely used in orthopedic extremity surgery for more than 150 years, both for prophylaxis and treatment of bacterial infection. However, relatively little literature exists regarding its utilization in spine surgery. This article describes ABC utilization in orthopedic surgery and explains the technique of ABC utilization in spine surgery. Surgeons can choose from multiple premixed ABCs with variable viscosities, setting times, and antibiotics or can mix in antibiotics to bone cements themselves. ABC can be used to fill large defects in the vertebral body or disc space or in some cases to coat instrumentation. Surgeons should be wary of complications such as ABC extravasation as well as an increased difficulty with revision. With a thorough understanding of the properties of the cement and the methods of delivery, ABC is a powerful adjunct in the treatment of spinal infections.

Nephrotoxicity Related to Antibiotic-Loaded Spacers in a 2-Stage Revision for Periprosthetic Joint Infection

Antibiotic-loaded bone cement (ALBC) spacers are the mainstay in 2-stage revision, but antibiotics (vancomycin plus aminoglycosides) may undergo systemic absorption, resulting in acute kidney injury (AKI). Data on spacer antibiotics are heterogeneous. Our objective was to review risk factors for AKI and dosage of antibiotics. Significant AKI risk factors were antibiotic concentration greater than 3 or 3.6 g per cement batch, comorbidities, chronic kidney disease, and hypovolemia. Despite similar spacer antibiotic dosing, there was remarkable variability in serum concentrations. To err on the side of caution, it appears that antibiotic dose below 3 g per cement batch might be relatively safe until more evidence surfaces. Consideration of risk factors for AKI calls for appropriate antibiotic use in 2-stage revision. [Orthopedics. 20XX;XX(X):xx-xx.].

Recent Development of Polydopamine Anti-Bacterial Nanomaterials

Polydopamine (PDA), as a mussel-inspired material, exhibits numerous favorable performance characteristics, such as a simple preparation process, prominent photothermal transfer efficiency, excellent biocompatibility, outstanding drug binding ability, and strong adhesive properties, showing great potential in the biomedical field. The rapid development of this field in the past few years has engendered substantial progress in PDA antibacterial materials. This review presents recent advances in PDA-based antimicrobial materials, including the preparation methods and antibacterial mechanisms of free-standing PDA materials and PDA-based composite materials. Furthermore, the urgent challenges and future research opportunities for PDA antibacterial materials are discussed.

A comparison of low-dose teicoplanin-loaded spacer application vs. high-dose vancomycin-and-gentamicin-loaded spacer application in the treatment of periprosthetic knee infection

Background/purpose

In the current study, our aim was to compare the efficacy and biocompatibility of teicoplanin-loaded and vancomycin-and-gentamicin-loaded articulating spacers used in two-stage revision arthroplasty for eradication of periprosthetic knee joint infection.

Methods

In the current retrospective cohort study, there were 24 patients who were given 2 g or less antibiotics per 40 g of cement in the low-dose teicoplanin group, and 20 patients who were given a total of 3.6 g or more antibiotics per 40 g of cement in the high-dose vancomycin and gentamicin group. Two groups were compared statistically.

Results

There was no statistically significant difference in the treatment failure between the two groups (p = 0.488). No statistically significant differences were found in spacer fracture rates between the two groups (p = 0.802).

Conclusion

The current study has demonstrated that low-dose teicoplanin protocol is as effective and safe as high-dose vancomycin and gentamycin protocol.

Current Concepts on the Application, Pharmacokinetics and Complications of Antibiotic-Loaded Cement Spacers in the Treatment of Prosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication of total joint replacement surgery. It affects about 2% of primary total joint replacements. Treatment aims at infection eradication and restoration of patient's mobility. Two-stage revision arthroplasty with an interim application of an antibiotic-loaded cement spacer (ALCS) is the widely accepted treatment for PJI. Spacers are powerful local carriers of antibiotics at the site of infection, effective against biofilm-protected microbes. On the other hand, spacers permit some mobility of the patient and facilitate final prosthesis implantation. ALCS's are either commercially available or prepared intraoperatively on prefabricated or improvised molds. Antibiotic elution from the spacer depends on the amount of the antibiotic used for cement impregnation, at the expense of mechanical stiffness of the spacer. The antibiotic should not exceed 4g per 40g of bone cement to preserve the mechanical properties of the cement. Spacers are frequently accompanied by local or systemic complications. The spacer may break, dislocate and compress vessels or nerves of the limb. Systemic complications are the result of excess elution of antibiotic and include nephrotoxicity, hepatotoxicity, ototoxicity, allergic reactions or neutropenia. Elderly patients with comorbidities are at risk to present such complications. Microbial resistance is a potential risk of long-lasting spacer retention. Persisting infection may require multiple spacer replacements.

Versatile polymer-based strategies for antibacterial drug delivery systems and antibacterial coatings

Human health damage and economic losses due to bacterial infections are very serious worldwide. Excessive use of antibiotics has caused an increase in bacterial resistance. Fortunately, various non-antibiotic antibacterial materials...

Cephalothin: Review of Characteristics, Properties and Status of Analytical Methods

BACKGROUND

Cephalothin (CET), a first generation cephalosporin, is the most efficient cephalosporin against resistant microorganisms. Many studies found in literature and pharmacopeias proposes analytical methods and, as most commonly, HPLC and microbiological assays.

OBJECTIVE

This paper shows a brief review of analytical method to quantify CET with a green analytical chemistry approach.

METHODS

The research data were collected from the literature and official compendia.

RESULTS

Most of the analytical methods to determine CET were performed by HPLC and agar diffusion in pharmaceuticals, blood, urine or water. Other analytical methods were found, as UV, Vis, iodometry, fluorimetry, IR/Raman, electrochemical among others, but, in less quantity. One important aspect is that these methods use organic and toxic solvents like methanol and acetonitrile, and only about 4% of the methods found uses water as solvent.

CONCLUSIONS

In this way, researches about analytical methods focused on green analytical chemistry for CET are of great importance and very relevant to optimize its analysis in pharmaceutical industries and to guarantee the quality of the product. More than just the development of new techniques it is possible to enhance of the ones that already exists applying the green analytical chemistry principles. In this way, it will be possible to reduce the environment impacts caused by these analytical procedures.

HIGHLIGHTS

This work shows a brief review of literature and pharmacopeias of analytical methods to quantify CET. Its quality control can be updated to meet the needs of current analytical chemistry and to fit into sustainable and eco-friendly analyzes.

Turbidimetric Method: A New, Ecological, and Fast Way to Evaluate of Vancomycin Potency

Background

Vancomycin, an antimicrobial, has many microbiological methods in literature, but it was not found any that follows the green chemistry principles.

Objective

The aim of this work was to develop and validate a new microbiological analytical method with a green view to determine the vancomycin potency in lyophilized powder using less quantity of diluents and culture medium, minimizing the costs and reducing the time of analysis.

Methods

The objective will be achieved using the microbiological method by turbidimetry.

Results

Water was used as the diluent to prepare the vancomycin solution. BHI broth as used as culture media for the growth of the S. aureus ATCC 25923. The method was linear in the range of 30, 39 and 50.7 µg/mL. It was selective, with vancomycin reference and sample absorbance values very similar. The precision of the method was proved at intraday (RSD 4.42 %), interday (RSD 3.56 %) and intermediate levels (RSD 2.03%). It was accurate with mean recovery of 100.71 % and robust when changes were performed in three parameters of the method and analyzed by the F-Test and t-Test.

Conclusions

The method for evaluating the potency of vancomycin in pharmaceutical product was successfully developed and validated.

Highlights

The method can be applied to routine quality control of vancomycin product as an alternative that contemplates the green analytical chemistry and the current pharmaceutical analyzes.

Progress of antibiotic-loaded bone cement in joint arthroplasty

Bone cement, consisting of polymethyl methacrylate, is a bioinert material used for prothesis fixation in joint arthroplasty. To treat orthopedic infections, such as periprosthetic joint infection, antibiotic-loaded bone cement (ALBC) was introduced into clinical practice. Recent studies have revealed the limitations of the antibacterial effect of ALBC. Moreover, with the increase in high infection risk patients and highly resistant microbes, more researches and modification of ALBC are required. This paper reviewed latest findings about ALBC for most popular and destructive pathogens, summarized the influence of antibiotic kind, drug dosage, application method, and environment towards characteristic of ALBC. Subsequently, new cement additives and clinical applications of ALBC in joint arthroplasty were also discussed.

Research into biocompatibility and cytotoxicity of daptomycin, gentamicin, vancomycin and teicoplanin antibiotics at common doses added to bone cement

OBJECTIVES

This study aims to investigate the biocompatibility and cytotoxicity of daptomycin, gentamicin, vancomycin and teicoplanin at commonly-used dose intervals added to polymethylmethacrylate (PMMA) in vitro.

MATERIALS AND METHODS

This prospective study was conducted between February 2016 and June 2016. Antibiotics were added to PMMA at doses frequently used in clinical practice. The antibiotic doses added were teicoplanin (2 g, 3 g, 4 g), gentamicin (0.5 g, 0.75 g, 1 g), daptomycin (0.5 g.) and vancomycin (2 g, 3 g, 4 g). Standard cement balls (10 mm) were created. Activated L929 mouse fibroblast cell culture was used for incubation. Agar diffusion, Cell Proliferation Kit II (XTT) test and electron microscope investigations were performed to examine biocompatibility and cytotoxicity.

RESULTS

In the cytotoxicity test, teicoplanin at 4 g and daptomycin at 0.5 g doses were observed to cause reductions in viability percentages. The same doses caused 20% and 20-40% cell lysis indices during the agar diffusion test. On electron microscope images, cytotoxic effects in fibroblast cells and involvement with the surface of cement balls were observed.

CONCLUSION

Gentamicin, vancomycin and teicoplanin were observed to be non-toxic and biocompatible at commonly-used dose intervals. Teicoplanin at 4 g and daptomycin at 0.5 g doses were identified to be cytotoxic and not biocompatible. When selecting antibiotics to be added to bone cement, care should be taken that the antibiotic is non-toxic and biocompatible.

Antimicrobial properties of antibiotic-loaded implants

AIMS

The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant Staphylococcus aureus (MSSA/MRSA) between the two groups.

METHODS

A total of 30 beads made of three different materials (tantalum/3D porous titanium and smooth titanium alloy) were bathed for one hour in a solution of 1 g vancomycin in 20 ml of sterile water for injection (bath concentration: 50 mg/mL). Ten 1 cm³ cylinders of antibiotic-loaded cement were also created by mixing standard surgical cement with 1 g of vancomycin in standardized sterile moulds. The cylinders were then placed on agar plates inoculated with MSSA and MRSA. The ZOIs were measured each day and the cylinders were transferred onto a new inoculated plate.

RESULTS

For MSSA and MRSA, no inhibitory effect was found in the control group, and antibiotic-loaded smooth titanium alloy beads showed a short inhibitory effect until day 2. For MSSA, both tantalum and 3D porous titanium beads showed significantly larger mean ZOIs than cement beads (all p < 0.01) each day until day 7 for tantalum and until day 3 for 3D porous titanium. After six days, antibiotic-loaded cement had significantly larger mean ZOIs than the 3D porous titanium (p = 0.027), but no significant difference was found with tantalum (p = 0.082). For MRSA, both tantalum and 3D porous titanium beads had significantly larger mean ZOIs than antibiotic-loaded cement each day until day 6 for tantalum (all p < 0.01) and until day 3 for 3D porous titanium (all p < 0.04). Antibiotic-loaded cement had significantly larger mean ZOIs than tantalum and 3D porous titanium from day 7 to 9 (all p < 0.042).

CONCLUSION

These results show that porous metal implants can deliver local antibiotics over slightly varying time frames based on in vitro analysis. Cite this article: Bone Joint J 2020;102-B(6 Supple A):158-162.

Current Status of Vancomycin Analytical Methods

BACKGROUND

The glycopeptide antibiotics are a class of antimicrobial drugs that are an important alternative for cases of bacterial infections resistant to penicillins, besides being able to be used to treat infections in people allergic to pencilin. They have great activity against Gram-positive microorganisms, including methicillin-resistant Staphylococcus aureus (MRSA), by inhibiting the cell wall synthesis.

OBJECTIVE

There are many analytical methods in the literature for determination of antimicrobial glycopeptide vancomycin in different matrixes that are very effective; however, all of them use toxic solvents, contributing to the generation of waste, causing damage to the environment and to the operator, as well as increased costs of analysis.

RESULTS

The most prevailing method found was high performance liquid chromatography (HPLC), followed by microbiological assays and, in less quantity, spectrometric methods. The chromatographic methods use organic solvents that are toxic, such as acetonitrile and methanol, and buffer solutions, that can damage the equipment and the column. In the microbiological assays the disc diffusion methods are still in the majority. The spectrophotometric methods were based in the UV-Vis region using buffer solutions as a diluent.

CONCLUSIONS

All these methods can become greener, following green analytical chemistry principles, which could bring benefits both to the environment and the operator, and reduce costs.

HIGHLIGHTS

In this paper, a literature review regarding analytical methods for determination of vancomycin was carried out with a suggestion of greener alternatives.

Toxic Effect of Vancomycin on Viability and Functionality of Different Cells Involved in Tissue Regeneration

To prevent infections local delivery of antibiotics is a useful tool. Especially in bone fractures, vancomycin impregnated bone cements are often used allowing high concentrations of antibiotics at the infection side without high serum concentrations. However, besides potential pathogens, cells involved in tissue regeneration may also be affected by the drug. We investigated the effect of vancomycin on the viability and functionality on osteoblasts, endothelial cells, fibroblasts and skeletal muscle cells. Our results show that the viability of all cells analyzed was reduced by vancomycin and that the observed effects were time and concentration dependent. The most pronounced toxic effect was detected on day three when even the lowest concentration of 0.01 mg/ml led to a significant decrease in proliferation compared to control. Functionality assays of osteoblasts and skeletal muscle cells revealed a sensitive reaction of the cells to the drug, indicating that vancomycin is toxic to these cells during the process of differentiation. These data suggest that the vancomycin administration is critical for cell survival and function. Therefore, the concentration of administered antibiotics needs to be carefully evaluated to find a balance between defense against pathogens and functionality of host cells and tissues.

Does the Addition of Poly(glycolide-co-lactide) to Teicoplanin-Containing Poly(methyl methacrylate) Beads Change the Elution Characteristics?

BACKGROUND

The objective of our study was to measure and compare the elution characteristics of teicoplanin from poly(methyl methacrylate) PMMA beads with those of poly(glycolide-co-lactide) PGLA-added beads.

METHODS

The study included two groups of PMMA + teicoplanin beads. PMMA was added to teicoplanin in Group 1 and PMMA + PGLA was added to teicoplanin in Group 2. A total of 16 beads of 1 cm³ were created for each group. Samples were added individually to tubes containing 3 ml of phosphate-buffered saline (PBS). Antibiotic elution was measured by measuring absorbance values of 1-ml samples taken at regular intervals using a UV-Vis spectrophotometer and cumulative percentages of drug release were calculated. In addition, the spectra of teicoplanin were identified using a FTIR spectrophotometer in a wavelength range of 400-4000 cm^-1.

RESULTS

Drug elution in the PBS medium was measured and compared for Groups 1 and 2. The cumulative percentage of drug release from the PGLA-added beads (Group 2) was significantly higher (p = 0.01). The molecular structure of teicoplanin was also confirmed using FTIR.

CONCLUSION

The in vitro results showed that the addition of biodegradable PGLA into bone cement functions as a water-soluble porogen which allows for significant increases in the elution of teicoplanin from cement. This increase in elution suggests that the PGLA would allow for further fluid contact and exchange with the previously entrapped drug. These results may have important clinical applications.

In Situ Gelling Hydrogel with Anti-Bacterial Activity and Bone Healing Property for Treatment of Osteomyelitis

Background

Despite the development of progressive surgical techniques and antibiotics, osteomyelitis is a big challenge for orthopedic surgeons. The main aim of this study is to fabricate an in situ gelling hydrogel that permits sustained release of antibiotic (for control of infection) and growth factor (for induction of new bone formation) for effective treatment of osteomyelitis.

Methods

An in situ gelling alginate (ALG)/hyaluronic acid (HA) hydrogel containing vancomycin (antibiotic) and bone morphogenetic protein-2 (BMP-2; growth factor) was prepared by simple mixing of ALG/HA/Na₂HPO₄ solution and CaSO₄/vancomycin/BMP-2 solution. The release behaviors of vancomycin and BMP-2, anti-bacterial effect (in vitro); and therapeutic efficiency for osteomyelitis and bone regeneration (in vivo, osteomyelitis rat model) of the vancomycin and BMP-2-incorporated ALG/HA hydrogel were investigated.

Results

The gelation time of the ALG/HA hydrogel was controlled into approximately 4 min, which is sufficient time for handling and injection into osteomyelitis lesion. Both vancomycin and BMP-2 were continuously released from the hydrogel for 6 weeks. From the in vitro studies, the ALG/HA hydrogel showed an effective anti-bacterial activity without significant cytotoxicity for 6 weeks. From an in vivo animal study using Sprague-Dawley rats with osteomyelitis in femur as a model animal, it was demonstrated that the ALG/HA hydrogel was effective for suppressing bacteria (Staphylococcus aureus) proliferation at the osteomyelitis lesion and enhancing bone regeneration without additional bone grafts.

Conclusions

From the results, we suggest that the in situ gelling ALG/HA hydrogel containing vancomycin and BMP-2 can be a feasible therapeutic tool to treat osteomyelitis.

Antibiotic-loaded tantalum may serve as an antimicrobial delivery agent

Aims

The aims of this study were to compare the mean duration of antibiotic release and the mean zone of inhibition between vancomycin-loaded porous tantalum cylinders and antibiotic-loaded bone cement at intervals, and to evaluate potential intrinsic antimicrobial properties of tantalum in an in vitro medium environment against methicillin-sensitive Staphylococcus aureus (MSSA).

Materials and Methods

Ten porous tantalum cylinders and ten cylinders of cement were used. The tantalum cylinders were impregnated with vancomycin, which was also added during preparation of the cylinders of cement. The cylinders were then placed on agar plates inoculated with MSSA. The diameter of the inhibition zone was measured each day, and the cylinders were transferred to a new inoculated plate. Inhibition zones were measured with a Vernier caliper and using an automated computed evaluation, and the intra- and interobserver reproducibility were measured. The mean inhibition zones between the two groups were compared with Wilcoxon’s test.

Results

MSSA was inhibited for 12 days by the tantalum cylinders and for nine days by the cement cylinders. At day one, the mean zone of inhibition was 28.6 mm for the tantalum and 19.8 mm for the cement group (p < 0.001). At day ten, the mean zone of inhibition was 3.8 mm for the tantalum and 0 mm for the cement group (p < 0.001). The porous tantalum cylinders soaked only with phosphate buffered solution showed no zone of inhibition.

Conclusion

Compared with cement, tantalum could release antibiotics for longer. Further studies should assess the advantages of using antibiotic-loaded porous tantalum implants at revision arthroplasty. Cite this article: Bone Joint J 2019;101-B:848–851.

Antibiotic Elution and Mechanical Strength of PMMA Bone Cement Loaded With Borate Bioactive Glass

Introduction: Local delivery of antibiotics using bone cement as the delivery vehicle is an established method of managing implant-associated orthopedic infections. Various fillers have been added to cement to increase antibiotic elution, but they often do so at the expense of strength. This study evaluated the effect of adding a borate bioactive glass, previously shown to promote bone formation, on vancomycin elution from PMMA bone cement.

Methods: Five cement composites were made: three loaded with borate bioactive glass along with 0, 1, and 5 grams of vancomycin and two without any glass but with 1 and 5 grams vancomycin to serve as controls. The specimens were soaked in PBS. Eluate of vancomycin was collected every 24 hours and analyzed by HPLC. Orthopedic-relevant mechanical properties of each composite were tested over time.

Results: The addition of borate bioactive glass provided an increase in vancomycin release at Day 1 and an increase in sustained vancomycin release throughout the treatment period. An 87.6% and 21.1% increase in cumulative vancomycin release was seen for both 1g and 5g loading groups, respectively. Compressive strength of all composites remained above the weight-bearing threshold of 70 MPa throughout the duration of the study with the glass-containing composites showing comparable strength to their respective controls.

Conclusion: The incorporation of borate bioactive glass into commercial PMMA bone cement can significantly increase the elution of vancomycin. The mechanical strength of the cement-glass composites remained above 70 MPa even after soaking for 8 weeks, suggesting their suitability for orthopedic weight-bearing applications.

Luminescence of Eu3+ ions in hybrid polymer-inorganic composites based on poly(methyl methacrylate) and zirconia nanoparticles

Spherical nanoparticles of ZrO₂ with 2 and 10 mol% EuO_1.5 up to 20 nm size were prepared by the method of hydrothermal synthesis for luminescent functionalization of the polymer-inorganic nanocomposites based on poly(methyl methacrylate). Surface modification of oxide nanoparticles was carried out by 3-(trimethoxysilyl)propyl methacrylate, dimethoxymethylvinyl silane and 2-hydroxyethyl methacrylate to provide uniform distribution and to prevent agglomeration of nanosized filler in the polymer matrix. Polymer-inorganic composites were synthesized by in situ free radical polymerization in bulk. Structuring of ZrO₂ -EuO_1.5 nanoparticles in the poly(methyl methacrylate) was studied by very-small-angle neutron scattering. According to the results, the dependence of photoluminescent properties of ZrO₂ -EuO_1.5 nanoparticles on the content of lanthanide, the symmetry of the crystal field, surface treatment and the polymer matrix were established. A correlation was shown between Stark splitting in luminescence spectra of ZrO₂ -EuO_1.5 nanoparticles and their phase composition. Using MMT-assay it was shown that composites based on poly(methyl methacrylate) and ZrO₂ -EuO_1.5 nanoparticles do not have cytotoxic properties, which makes it possible to use them as prosthesis materials with contrasted and luminescent imaging properties.

In vitro methods for the evaluation of antimicrobial surface designs

Bacterial adhesion and subsequent biofilm formation on biomedical implants and devices are a major cause of their failure. As systemic antibiotic treatment is often ineffective, there is an urgent need for antimicrobial biomaterials and coatings. The term "antimicrobial" can encompass different mechanisms of action (here termed "antimicrobial surface designs"), such as antimicrobial-releasing, contact-killing or non-adhesivity. Biomaterials equipped with antimicrobial surface designs based on different mechanisms of action require different in vitro evaluation methods. Available industrial standard evaluation tests do not address the specific mechanisms of different antimicrobial surface designs and have therefore been modified over the past years, adding to the myriad of methods available in the literature to evaluate antimicrobial surface designs. The aim of this review is to categorize fourteen presently available methods including industrial standard tests for the in vitro evaluation of antimicrobial surface designs according to their suitability with respect to their antimicrobial mechanism of action. There is no single method or industrial test that allows to distinguish antimicrobial designs according to all three mechanisms identified here. However, critical consideration of each method clearly relates the different methods to a specific mechanism of antimicrobial action. It is anticipated that use of the provided table with the fourteen methods will avoid the use of wrong methods for evaluating new antimicrobial designs and therewith facilitate translation of novel antimicrobial biomaterials and coatings to clinical use. The need for more and better updated industrial standard tests is emphasized.

STATEMENT OF SIGNIFICANCE

European COST-action TD1305, IPROMEDAI aims to provide better understanding of mechanisms of antimicrobial surface designs of biomaterial implants and devices. Current industrial evaluation standard tests do not sufficiently account for different, advanced antimicrobial surface designs, yet are urgently needed to obtain convincing in vitro data for approval of animal experiments and clinical trials. This review aims to provide an innovative and clear guide to choose appropriate evaluation methods for three distinctly different mechanisms of antimicrobial design: (1) antimicrobial-releasing, (2) contact-killing and (3) non-adhesivity. Use of antimicrobial evaluation methods and definition of industrial standard tests, tailored toward the antimicrobial mechanism of the design, as identified here, fulfill a missing link in the translation of novel antimicrobial surface designs to clinical use.

In Vitro Effect of Vancomycin on the Viability of Articular Chondrocytes

OBJECTIVES

To characterize the in vitro toxicity of vancomycin on articular cartilage.

METHODS

Osteochondral samples extracted from fresh, juvenile porcine stifle (knee) joints were exposed to vancomycin saline concentrations of 2, 5, and 10 mg/mL and compared with a saline and nonsaline treated control. Comparison of chondrocyte viability was assessed with histology examination of chondrocyte degeneration using the Mankin criteria and a live/dead staining using ethidium homodimer-2 and calcien acetoxymethylester stain and confocal laser scanning microscopy.

RESULTS

A comparison of chondrocyte viability in the control sample and 2 mg/mL group showed no statistical difference (P = 0.38). The chondrocyte toxicity was statistically significantly higher in both the 5 mg/mL (P = 0.003) and 10 mg/mL (P < 0.001) experimental groups in comparison to the control sample. Chondrocyte death increased in a statistically significant dose-dependent fashion. Histologically, the Mankin scores were higher for the saline-treated group in comparison to the untreated control group.

CONCLUSIONS

Vancomycin is toxic to articular chondrocytes in concentrations of 5 mg/mL and greater. Strategies for controlling concentration must be developed before routine application of topical antibiotics around synovial joints is performed.

Levofloxacin-loaded bone cement delivery system: Highly effective against intracellular bacteria and Staphylococcus aureus biofilms

Staphylococcus aureus is a major pathogen in bone associated infections due to its ability to adhere and form biofilms on bone and/or implants. Moreover, recrudescent and chronic infections have been associated with S. aureus capacity to invade and persist within osteoblast cells. With the growing need of novel therapeutic tools, this research aimed to evaluate some important key biological properties of a novel carrier system composed of acrylic bone cement (polymethylmethacrylate - PMMA), loaded with a release modulator (lactose) and an antibiotic (levofloxacin). Levofloxacin-loaded bone cement (BC) exhibited antimicrobial effects against planktonic and biofilm forms of S. aureus (evaluated by a flow chamber system). Moreover, novel BC formulation showed high anti-bacterial intraosteoblast activity. This fact led to the conclusion that levofloxacin released from BC matrices could penetrate the cell membrane of osteoblasts and be active against S. aureus strains in the intracellular environment. Furthermore, levofloxacin-BC formulations showed no significant in vitro cytotoxicity and no allergic potential (measured by the in vivo chorioallantoic membrane assay). Our results indicate that levofloxacin-loaded BC has potential as a local antibiotic delivery system for treating S. aureus associated bone infections.

Characterisation of the selective binding of antibiotics vancomycin and teicoplanin by the VanS receptor regulating type A vancomycin resistance in the enterococci

A-type resistance towards "last-line" glycopeptide antibiotic vancomycin in the leading hospital acquired infectious agent, the enterococci, is the most common in the UK. Resistance is regulated by the VanRASA two-component system, comprising the histidine sensor kinase VanSA and the partner response regulator VanRA. The nature of the activating ligand for VanSA has not been identified, therefore this work sought to identify and characterise ligand(s) for VanSA. In vitro approaches were used to screen the structural and activity effects of a range of potential ligands with purified VanSA protein. Of the screened ligands (glycopeptide antibiotics vancomycin and teicoplanin, and peptidoglycan components N-acetylmuramic acid, D-Ala-D-Ala and Ala-D-y-Glu-Lys-D-Ala-D-Ala) only glycopeptide antibiotics vancomycin and teicoplanin were found to bind VanSA with different affinities (vancomycin 70μM; teicoplanin 30 and 170μM), and were proposed to bind via exposed aromatic residues tryptophan and tyrosine. Furthermore, binding of the antibiotics induced quicker, longer-lived phosphorylation states for VanSA, proposing them as activators of type A vancomycin resistance in the enterococci.

Activity of Fosfomycin- and Daptomycin-Containing Bone Cement on Selected Bacterial Species Being Associated with Orthopedic Infections

The purpose of this study was to determine activity of fosfomycin/gentamicin and daptomycin/gentamicin-containing PMMA bone-cement against Staphylococcus aureus (MRSA, MSSA), Staphylococcus epidermidis, Enterococcus faecium (VRE), and E. coli (ESBL; only fosfomycin). Test specimens of the bone cement were formed and bacteria in two concentrations were added one time or repeatedly up to 96 h. All fosfomycin-containing cement killed ultimately all MSSA, Staphylococcus epidermidis, and E. coli within 24 h; growth of MRSA was suppressed up to 48 h. Activity of daptomycin-containing cement depended on the concentration; the highest concentrated bone cement used (1.5 g daptomycin/40 g of powder) was active against all one-time added bacteria. When bacteria were added repeatedly to fosfomycin-containing cement, growth was suppressed up to 96 h and that of MRSA and VRE only up to 24 h. The highest concentration of daptomycin suppressed the growth of repeated added bacteria up to 48 h (VRE) until 96 h (MSSA, MRSA). In conclusion, PMMA bone cement with 1.5 g of daptomycin and 0.5 g of gentamicin may be an alternative in treatment of periprosthetic infections caused by Gram-positive bacteria.

Role of Antibiotic Cement Coated Nailing in Infected Nonunion of Tibia

Introduction

Infected nonunion of long bones is a chronic and debilitating disorder. It is more difficult to deal with when the implant used for internal fixation itself becomes a potential media for infection because of bacterial adhesion and biofilm formation. Traditionally, it is managed by two-stage procedure for controlling the infection first and then treating the nonunion. This study has been undertaken to explore antibiotic cement coated nailing as single stage treatment modality for treating infection and achieving stability at the same time.

Materials and Methods

Twenty patients (above 18 years of age) with infected nonunion of tibia with bone gap less than 2 cm were managed using antibiotic cement coated K-nail. Antibiotic cement nail was prepared using endotracheal tube method. Antibiotics used were a combination of vancomycin and teicoplanin.

Results

Infection was controlled in 95% of the patients. Bony union was achieved in 12 of 20 (60%) patients with antibiotic cement nailing as the only procedure with average time of union of 32 weeks. Remaining 8 patients required additional procedures like bone grafting or exchange nailing and these were done in six patients, with union of fracture. Two patients refused to undergo further procedures. Complications encountered were difficult nail removal in three cases, broken nail in two cases, and bent nail in one case. Recurrence of infection was observed in two patients. Average period of follow-up was 13 months.

Conclusion

Antibiotic cement impregnated nailing is a simple, economical and effective single stage procedure for the management of infected nonunion of tibia. It is advantageous over external fixators, as it eliminates the complications of external fixators and has good patient compliance. The method utilizes existing easily available instrumentation and materials and is technically less demanding, and therefore can be performed at any general orthopaedic center.

Osteomyelitis: Recent advances in pathophysiology and therapeutic strategies

This review article summarizes the recent advances in pathogenic mechanisms and novel therapeutic strategies for osteomyelitis, covering both periprosthetic joint infections and fracture-associated bone infections. A better understanding of the pathophysiology including the mechanisms for biofilm formation has led to new therapeutic strategies for this devastating disease. Research on novel local delivery materials with appropriate mechanical properties, lower exothermicity, controlled release of antibiotics, and absorbable scaffolding for bone regeneration is progressing rapidly. Emerging strategies for prevention, early diagnosis of low-grade infections, and innovative treatments of osteomyelitis such as biofilm disruptors and immunotherapy are highlighted in this review.

Inhibitory effects of vancomycin and fosfomycin on methicillin-resistant Staphylococcus aureus from antibiotic-impregnated articulating cement spacers

Objectives

Vancomycin and fosfomycin are antibiotics commonly used to treat methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the in vitro inhibitory effects against MRSA of articulating cement spacers impregnated with either vancomycin or fosfomycin.

Methods

Vancomycin-impregnated articulating cement spacers and fosfomycin-impregnated articulating cement spacers were immersed in sterile phosphate-buffered saline (PBS) solutions and then incubated. Samples were collected for bioactivity evaluation. The aliquots were tested for MRSA inhibition with the disc diffusion method, and the inhibition zone diameters were measured. The inhibition zone differences were evaluated using the Wilcoxon Rank Sum Test.

Results

The vancomycin group had significantly larger inhibition zones than the fosfomycin group from day three through to completion of the fourth week of incubation (p < 0.001). The vancomycin group exhibited a MRSA inhibition zone up to four weeks but the fosfomycin group showed an inhibition zone for only three days and after that did not show the the potential to inhibit MRSA.

Conclusion

This in vitro study found that the inhibitory effect of vancomycin-impregnated articulating cement spacers against MRSA outperformed fosfomycin-impregnated articulating cement spacers. Further comparing our results to other published reports suggests there might be a limitation of the disc diffusion bioassay to show a large inhibitory zone in a high concentration of a highly soluble antibiotic.

Cite this article: V. Yuenyongviwat, N. Ingviya, P. Pathaburee, B. Tangtrakulwanich. Inhibitory effects of vancomycin and fosfomycin on methicillin-resistant Staphylococcus aureus from antibiotic-impregnated articulating cement spacers. Bone Joint Res 2017;6:132–136. DOI: 10.1302/2046-3758.63.2000639.

Development of advanced biantibiotic loaded bone cement spacers for arthroplasty associated infections

The incidence increase of infections in patients with hip or knee implants with resistant pathogens (mainly some S. coagulase-negative and gram positive bacteria) demands advanced antibiotic loaded formulations. In this paper, we report the design of new biantibiotic acrylic bone cements for in situ delivery. They include a last generation antibiotic (daptomycin or linezolid) in combination with vancomycin and are performed based on a novel modification of the Palacos R^® acrylic bone cement, which is based on two components, a liquid (methyl methacrylate) and a solid (polymeric phase). Hence, the solid component of the experimental formulations include 45wt% of microparticles of poly(D,L-lactic-co-glycolic) acid, 55wt% of poly(methyl methacrylate) beads and supplements (10wt-% each) of antibiotics. These formulations provide a selective and excellent control of the local release of antibiotics during a long time period (up to 2 months), avoiding systemic dissemination. The antimicrobial activity of the advanced spacers tested against S. aureus shows that single doses would be enough for the control of the infection. In vitro biocompatibility of cements on human osteoblasts is ensured. This paper is mainly focused on the preparation and characterization of cements and the studies of elution kinetics and bactericidal effects. Developed formulations are proposed as spacers for the treatment of infected arthroplasties, but also, they could be applied in other antibiotic devices to treat relevant bone-related infection diseases.

Peptide hormones and lipopeptides: from self-assembly to therapeutic applications

This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions. The self-assembly of these types of molecules is outlined, and how this can impact on bioactivity. Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

Vancomycin and Ceftazidime in Bone Cement as a Potentially Effective Treatment for Knee Periprosthetic Joint Infection

BACKGROUND

The aim of this study was to determine the optimal formulation of antibiotic-loaded bone cement for knee periprosthetic joint infection. We used both in vitro and in vivo models incorporating various broad-spectrum antibiotics and tested their efficacy against gram-positive and gram-negative bacteria.

METHODS

Bone cement specimens loaded with 4 g of either vancomycin or teicoplanin and 4 g of ceftazidime, imipenem, or aztreonam were studied to measure their in vitro antibiotic release characteristics and antibacterial capacities against methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Bone cement spacers loaded with the antibiotics with the superior in vitro antibacterial capacity were then implanted into 8 patients (4 women and 4 men between 51 and 79 years of age) diagnosed with chronic knee periprosthetic joint infection. The antibiotic concentrations and antibacterial activities in the joint fluid at the site of the infection were measured following spacer implantation.

RESULTS

Cement samples loaded with vancomycin and ceftazidime exhibited in vitro antibacterial activity against the test microorganisms that lasted for as long as or longer than that of cement loaded with the other antibiotic combinations. Joint fluid samples exhibited activity against bacteria including American Type Culture Collection (ATCC) strains and clinically isolated strains.

CONCLUSIONS

Bone cement loaded with vancomycin and ceftazidime provided broad-spectrum antibacterial capacity both in vitro and in vivo and was shown to be a potentially effective therapeutic measure in the treatment of knee periprosthetic joint infections.

CLINICAL RELEVANCE

This study confirmed the potential effectiveness of drug delivery from bone cement spacers impregnated with vancomycin and ceftazidime.

Elution and Mechanical Strength of Vancomycin-Loaded Bone Cement: In Vitro Study of the Influence of Brand Combination

Antibiotic-loaded bone cement (ALBC) is widely used in orthopaedic surgery for both prevention and treatment of infection. Little is known about the effect of different brand combinations of antibiotic and bone cement on the elution profile and mechanical strength of ALBC. Standardized specimens that consisted of one of the 4 brands of bone cement and one of the 3 brands of vancomycin were fashioned, producing 12 combinations of ALBC. Two dosages of vancomycin in 40g bone cement were used to represent the high (4g vancomycin) and low (1g vancomycin) dose groups. Concentrations of vancomycin elution from ALBC was measured for up to 336 hours. The ultimate compression strength was tested at axial compression using a material testing machine before and after elution. In both high-dose and low-dose groups, Lyo-Vancin in PALACOS bone cement resulted in the highest cumulative elution and Vanco in Simplex P bone cement resulted in the lowest elution (458% and 65% higher in high- and low-dose groups, respectively). The mechanical strength was not significantly compromised in all groups with low dose vancomycin (range: 70.31 ± 2.74 MPa to 87.28 ± 8.26MPa after elution). However, with the addition of high dose vancomycin, there was a mixed amount of reduction in the ultimate compression strength after cement aging, ranging from 5% (Vanco in Simplex P, 81.10 ± 0.48 MPa after elution) to 38% (Sterile vancomycin in CMW, 60.94 ± 5.74 MPa after elution). We concluded that the selection of brands of vancomycin and bone cement has a great impact on the release efficacy and mechanical strength of ALBC.

Antibiotic-eluting hydrophilized PMMA bone cement with prolonged bactericidal effect for the treatment of osteomyelitis

Osteomyelitis is still considered to be one of the major challenges for orthopedic surgeons despite advanced antiseptic surgical procedures and pharmaceutical therapeutics. In this study, hydrophilized poly(methyl methacrylate) (PMMA) bone cements containing Pluronic F68 (EG79PG28EG79) as a hydrophilic additive and vancomycin ( F68-VA cements) were prepared to allow the sustained release of the antibiotic for adequate periods of time without any significant loss of mechanical properties. The compressive strengths of the bone cements with Pluronic F68 compositions less than 7 wt% were not significantly different compared with the control vancomycin-loaded bone cement ( VA cement). The F68 (7 wt%)-VA cement showed sustained release of the antibiotic for up to 11 weeks and almost 100% release from the bone cement. It also prohibited the growth of S. aureus (zone of inhibition) over six weeks (the required period to treat osteomyelitis), and it did not show any notable cytotoxicity. From an animal study using a femoral osteomyelitis rat model, it was observed that the F68 (7 wt%)-VA cement was effective for the treatment of osteomyelitis, probably as a result of the prolonged release of antibiotic from the PMMA bone cement. On the basis of these findings, it can be suggested that the use of Pluronic F68 as a hydrophilic additive for antibiotic-eluting PMMA bone cement can be a promising strategy for the treatment of osteomyelitis.

Two-Stage Cementless Revision Total Hip Arthroplasty for Infected Primary Hip Arthroplasties

The main purpose of the present study was to analyze the clinical features, the most common infective agents, and the results of two-stage total hip revision using a teicoplanin-impregnated spacer. Between January 2005 and July 2011, 41 patients were included. At the clinical status analysis, physical examination was performed, Harris hip score was noted, isolated microorganisms were recorded, and the radiographic evaluation was performed. The mean Harris hip score was improved from 38.9 ± 9.6 points to 81.8 ± 5.8 points (P<0.05). Infection was eradicated in 39 hips. Radiographic evidence of stability was noted in 37 acetabular revision components, and all femoral stems. Two-stage revision of the infected primary hip arthroplasty is a time-consuming but a reliable procedure with high rates of success.

The effects of different mixing speeds on the elution and strength of high-dose antibiotic-loaded bone cement created with the hand-mixed technique

We evaluated the effects of the mixing speed of hand-mixed bone cement and the different phases of antibiotic mixing on the elution, mechanical properties, and porosity of antibiotic-loaded bone cement. Vancomycin-loaded Palacos LV bone cement was prepared at two hand-mixing speeds, normal and high-speed, and with antibiotic addition during three phases (directly mixing with the PMMA powder, in the liquid phase, and in the dough phase). The cumulative antibiotic elution over 15 days in the high-speed group was increased by 24% compared with the normal-speed group (P < 0.001). The delayed antibiotic addition produced higher vancomycin elution (P < 0.05), but no difference was observed between the liquid and dough phases (P > 0.05). Our study demonstrated that bone cement prepared with high-speed hand mixing and delayed antibiotic addition can exhibit increased vancomycin release.

Biodegradable drug-eluting nanofiber-enveloped implants for sustained release of high bactericidal concentrations of vancomycin and ceftazidime: in vitro and in vivo studies

We developed biodegradable drug-eluting nanofiber-enveloped implants that provided sustained release of vancomycin and ceftazidime. To prepare the biodegradable nanofibrous membranes, poly(D,L)-lactide-co-glycolide and the antibiotics were first dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol. They were electrospun into biodegradable drug-eluting membranes, which were then enveloped on the surface of stainless plates. An elution method and a high-performance liquid chromatography assay were employed to characterize the in vivo and in vitro release rates of the antibiotics from the nanofiber-enveloped plates. The results showed that the biodegradable nanofiber-enveloped plates released high concentrations of vancomycin and ceftazidime (well above the minimum inhibitory concentration) for more than 3 and 8 weeks in vitro and in vivo, respectively. A bacterial inhibition test was carried out to determine the relative activity of the released antibiotics. The bioactivity ranged from 25% to 100%. In addition, the serum creatinine level remained within the normal range, suggesting that the high vancomycin concentration did not affect renal function. By adopting the electrospinning technique, we will be able to manufacture biodegradable drug-eluting implants for the long-term drug delivery of different antibiotics.

Liquid antibiotics in bone cement: an effective way to improve the efficiency of antibiotic release in antibiotic loaded bone cement

Objectives

The objective of this study was to compare the elution characteristics, antimicrobial activity and mechanical properties of antibiotic-loaded bone cement (ALBC) loaded with powdered antibiotic, powdered antibiotic with inert filler (xylitol), or liquid antibiotic, particularly focusing on vancomycin and amphotericin B.

Methods

Cement specimens loaded with 2 g of vancomycin or amphotericin B powder (powder group), 2 g of antibiotic powder and 2 g of xylitol (xylitol group) or 12 ml of antibiotic solution containing 2 g of antibiotic (liquid group) were tested.

Results

Vancomycin elution was enhanced by 234% in the liquid group and by 12% in the xylitol group compared with the powder group. Amphotericin B elution was enhanced by 265% in the liquid group and by 65% in the xylitol group compared with the powder group. Based on the disk-diffusion assay, the eluate samples of vancomycin-loaded ALBC of the liquid group exhibited a significantly larger inhibitory zone than samples of the powder or the xylitol group. Regarding the ALBCs loaded with amphotericin B, only the eluate samples of the liquid group exhibited a clear inhibitory zone, which was not observed in either the xylitol or the powder groups. The ultimate compressive strength was significantly reduced in specimens containing liquid antibiotics.

Conclusions

Adding vancomycin or amphotericin B antibiotic powder in distilled water before mixing with bone cement can significantly improve the efficiency of antibiotic release than can loading ALBC with the same dose of antibiotic powder. This simple and effective method for preparation of ALBCs can significantly improve the efficiency of antibiotic release in ALBCs.

Cite this article: Bone Joint Res 2014;3:246–51.

Intra-articular pharmacokinetics of a gentamicin impregnated collagen sponge in the canine stifle: an experimental study

OBJECTIVE

To investigate local and systemic pharmacokinetics of gentamicin after intra-articular implantation of a gentamicin impregnated collagen sponge (GICS) in the inflamed canine joint.

STUDY DESIGN

Descriptive repeated measures experimental study.

ANIMALS

Dogs (n = 9).

METHODS

Stifle joint inflammation was caused by urate injection. Twenty-four hours later a GICS (gentamicin dose, 6 mg/kg) was arthroscopically implanted. Synovial fluid and plasma gentamicin concentrations were measured for 14 days after implantation, and pharmacokinetic parameters modeled using statistical moment analyses.

RESULTS

Intra-articular gentamicin concentrations fell to sub-MIC for Staphylococcus sp. (4 µg/mL) by 22.4 hours (95% CI: 18.6-26.2) after sponge implantation. Cmax synovial was 2397 µg/mL (95%CI: 1161-3634 µg/mL) at 1.2 hours (95%CI: 0.5-1.8 hours). Plasma gentamicin concentrations achieved levels of Cmax plasma  = 8.0 µg/mL (95%CI: 6.1-10.0 µg/mL) at 1.5 hours (95%CI: 0.8-2.1) after GICS placement and fell below target trough of 2.0 µg/mL by 5.6 hours (95%CI: 4.7-6.5 hours) after GICS placement.

CONCLUSIONS

Intra-articular gentamicin concentration after GICS placement at an IV-equivalent dose reached high levels and declined rapidly. The maximum plasma levels attained were ∼1/3 of the recommended sub-toxic target for people after parenteral gentamicin administration.

Charcot neuroarthropathy of the foot and ankle: diagnosis and management strategies

This article reviews current literature discussing the etiology, pathophysiology, diagnosis and imaging, and conservative and surgical treatment of Charcot osteoarthropathy. The treatment of Charcot osteoarthropathy with concurrent osteomyelitis is also discussed.

Gentamicin in bone cement: A potentially more effective prophylactic measure of infectionin joint arthroplasty

Objectives

The objective of this study is to determine an optimal antibiotic-loaded bone cement (ALBC) for infection prophylaxis in total joint arthroplasty (TJA).

Methods

We evaluated the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with vancomycin, teicoplanin, ceftazidime, imipenem, piperacillin, gentamicin, and tobramycin against methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staph. aureus (MRSA), coagulase-negative staphylococci (CoNS), Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Standardised cement specimens made from 40 g PMMA loaded with 1 g antibiotics were tested for elution characteristics, antibacterial activities, and compressive strength in vitro.

Results

The ALBC containing gentamicin provided a much longer duration of antibiotic release than those containing other antibiotic. Imipenem-loading on the cement had a significant adverse effect on the compressive strength of the ALBC, which made it insufficient for use in prosthesis fixation. All of the tested antibiotics maintained their antibacterial properties after being mixed with PMMA. The gentamicin-loaded ALBC provided a broad antibacterial spectrum against all the test organisms and had the greatest duration of antibacterial activity against MSSA, CoNS, P. aeruginosa and E. coli.

Conclusion

When considering the use of ALBC as infection prophylaxis in TJA, gentamicin-loaded ALBC may be a very effective choice.

Cite this article: Bone Joint Res 2013;2:220–6.

A daptomycin-xylitol-loaded polymethylmethacrylate bone cement: how much xylitol should be used?

BACKGROUND

The rate of release of an antibiotic from an antibiotic-loaded polymethylmethacrylate (PMMA) bone cement is low. This may be increased by adding a particulate poragen (eg, xylitol) to the cement powder. However, the appropriate poragen amount is unclear.

QUESTIONS/PURPOSES

We explored the appropriate amount of xylitol to use in a PMMA bone cement loaded with daptomycin and xylitol.

METHODS

We prepared four groups of cement, each comprising the same amount of daptomycin in the powder (1.36 g/40 g dry powder) but different amounts of xylitol (0, 0.7, 1.4, and 2.7 g); the xylitol mass ratio (X) (mass divided by mass of the final dry cement-daptomycin-xylitol mixture) ranged from 0 to 6.13 wt/wt%. Eight mechanical, antibiotic release, and bacterial inhibitory properties were determined using three to 22 specimens or replicates per test. We then used an optimization method to determine an appropriate value of X by (1) identifying the best-fit relationship between the value of each property and X, (2) defining a master objective function incorporating all of the best fits; and (3) determining the value of X at the maximum master objective function.

RESULTS

We found an appropriate xylitol amount to be 4.46 wt/wt% (equivalent to 1.93 g xylitol mixed with 1.36 g daptomycin and 40 g dry cement powder).

CONCLUSIONS

We demonstrated a method that may be used to determine an appropriate xylitol amount for a daptomycin-xylitol-loaded PMMA bone cement. These findings will require in vivo confirmation.

CLINICAL RELEVANCE

While we identified an appropriate amount of xylitol in a daptomycin-xylitol-loaded PMMA bone cement as a prophylactic agent in total joint arthroplasties, clinical evaluations are needed to confirm the effectiveness of this cement.

Charcot foot and ankle with osteomyelitis

This paper presents a review of the current literature discussing topics of Charcot osteoarthropathy, osteomyelitis, diagnosing osteomyelitis, antibiotic management of osteomyelitis, and treatment strategies for management of Charcot osteoarthropathy with concurrent osteomyelitis.

The use of antimicrobial-impregnated PMMA to manage periprosthetic infections: controversial issues and the latest developments

Despite improvements in intraoperative antimicrobial procedures, in surgical techniques and in implant design for joint replacement, periprosthetic infection after arthroplasty is still one of the most challenging problems encountered by orthopedic surgeons. Systemic antibiotics are not sufficiently effective to eradicate such deep infections because of the impaired blood circulation and low antibiotic concentration at the implantation site. As a local drug delivery system, antibiotic-impregnated PMMA (polymethylmethacrylate) bone cements have been widely used for prophylaxis or treatment of deep infections after total joint replacement. However, the effectiveness of antibiotic-loaded PMMA in preventing infections after arthroplasty is still controversial. Furthermore, the outcomes of established deep infections treated with this technique are not consistent. The local use of antibiotics has led to the emergence of antibiotic-resistant bacterial strains and has adverse effects on the function of osteogenic cells. Recently, many efforts have been made to identify new antibacterial agents that can be loaded into PMMA. These antimicrobial agents should exhibit good antibacterial activity against antibiotic-resistant strains and should simultaneously enhance osteointegration between the PMMA and the bone tissue. PMMA loaded with chitosan or chitosan derivatives has been demonstrated to induce improved osteogenic activity and to exhibit antibacterial activity in a preclinical study.