Fibrin glue-antibiotic suspension in the prevention of prosthetic graft infection

A novel antimicrobial coating to prevent periprosthetic joint infection

Aims

Periprosthetic joint infection (PJI) is a debilitating condition with a substantial socioeconomic burden. A novel autologous blood glue (ABG) has been developed, which can be prepared during surgery and sprayed onto prostheses at the time of implantation. The ABG can potentially provide an antimicrobial coating which will be effective in preventing PJI, not only by providing a physical barrier but also by eluting a well-known antibiotic. Hence, this study aimed to assess the antimicrobial effectiveness of ABG when impregnated with gentamicin and stem cells.

Methods

Gentamicin elution from the ABG matrix was analyzed and quantified in a time-dependent manner. The combined efficiency of gentamicin and ABG as an anti-biofilm coating was investigated on titanium disks.

Results

ABG-gentamicin was bactericidal from 10 μg/ml and could release bactericidal concentrations over seven days, preventing biofilm formation. A concentration of 75 μg/ml of gentamicin in ABG showed the highest bactericidal effect up to day 7. On titanium disks, a significant bacterial reduction on ABG-gentamicin coated disks was observed when compared to both uncoated (mean 2-log reduction) and ABG-coated (mean 3-log reduction) disks, at days 3 and 7. ABG alone exhibited no antimicrobial or anti-biofilm properties. However, a concentration of 75 μg/ml gentamicin in ABG sustains release over seven days and significantly reduced biofilm formation. Its use as an implant coating in patients with a high risk of infection may prevent bacterial adhesion perioperatively and in the early postoperative period.

Conclusion

ABG’s use as a carrier for stem cells was effective, as it supported cell growth. It has the potential to co-deliver compatible cells, drugs, and growth factors. However, ABG-gentamicin’s potential needs to be further justified using in vivo studies.

Cite this article: Bone Joint Res 2020;9(12):848–856.

Fibrin matrices: The versatile therapeutic delivery systems

Fibrin sealants, that have been employed for over a century by surgeons to stop post surgery bleeding, are finding novel applications in the controlled delivery of antibiotics and several other therapeutics. Fibrinogen can be easily purified from blood plasma and converted by thrombolysis to fibrin that undergoes spontaneous aggregation to form insoluble clot. During the gelling, fibrin can be formulated into films, clots, threads, microbeads, nanoconstructs and nanoparticles. Whole plasma clots in the form of beads and microparticles can also be prepared by activating endogenous thrombin, for possible drug delivery. Fibrin formulations offer remarkable scope for controlling the porosity as well as in vivo degradability and hence the release of the associated therapeutics. Binding/covalent-linking of therapeutics to the fibrin matrix, crosslinking of the matrix with bifunctional reagents and coentrapment of protease inhibitors have been successful in regulating both in vitro and in vivo release of the therapeutics. The release rates can also be remarkably lowered by preentrapment of therapeutics in insoluble particles like liposomes or by anchoring them to the matrix via molecules that bind them as well as fibrin.

Local Antibiotic Prophylaxis in Surgery

The perioperative use of antibiotics is an established and accepted technique for the prevention of postoperative infection. Intravenous administration often is preferred, and intramuscular administration is possible, although it has certain drawbacks. This article examines a variety of other routes of administration for delivering antibiotics locally to the surgical site. These techniques merit further study in prospectively randomized trials.

The use of tissue sealants to deliver antibiotics to an orthopaedic surgical site with a titanium implant

BACKGROUND

Orthopaedic surgery is associated with unacceptable infection rates that respond poorly to systemic antibiotics. The objective of this study was to use an animal model for orthopaedic implant infection to examine the ability of a new-generation fibrin tissue sealant to effectively deliver antibiotics to the surgical site.

METHODS

The antibiotics cefazolin, fusidic acid or 5-fluorouracil were blended into Vitagel tissue sealant. The release rate of the drugs was measured using HPLC methods and bioactivity was measured by the zone of inhibition method with pathogenic Staphylococcus aureus. The antibiotic activity of the drug-loaded sealant was then tested in rats using infected orthopaedic surgical sites (titanium clip on spine). Efficacy was evaluated by residual bacterial counts on clips, clinical observations of infection, and histological findings.

RESULTS

The drugs were released in a controlled manner over 2-4 days. All three antibiotics demonstrated strong antibacterial activity when released from the sealants. None of the treated animals demonstrated systemic illness. Post mortem dissection revealed a well-encapsulated abscess surrounding the titanium clip with erosion of the bony process. Using an inoculum of 1-5 × 10(3) CFU, treatment with antibiotic-loaded fibrin sealant demonstrated reduced infective swelling and reduced bacterial counts on surgical clip swabs compared to control rats or rats treated with antibiotic only. This model allowed for almost 100 % infectivity with a 0 % mortality rate due to infection, mimicking the clinical features of human implant infection.

CONCLUSION

The results support the use of antibiotic-loaded commercially available fibrin sealants to prevent infection after implant surgery.

A pilot study of a triple antimicrobial-bonded Dacron graft for the prevention of aortic graft infection

OBJECTIVE

Perioperative infection of an aortic graft is one of the most devastating complications of vascular surgery, with a mortality rate of 10% to 30%. The rate of amputation of the lower limbs is generally >25%, depending on the graft material, the location of the graft and infection, and the bacterial virulence. In vitro studies suggest that an antibiotic-impregnated graft may help prevent perioperative graft infection. In a pilot animal study, we tested a locally developed technique of bonding Dacron aortic grafts with three antimicrobial agents to evaluate the ensuing synergistic preventive effect on direct perioperative bacterial contamination.

METHODS

We surgically implanted a 6-mm vascular knitted Dacron graft in the infrarenal abdominal aorta of six Sinclair miniature pigs. Two pigs received unbonded, uninoculated grafts; two received unbonded, inoculated grafts; and two received inoculated grafts that were bonded with chlorhexidine, rifampin, and minocycline. Before implantation, the two bonded grafts and the two unbonded grafts were immersed for 15 minutes in a 2-mL bacterial solution containing 1 to 2 × 10(7) colony-forming units (CFU)/mL of Staphylococcus aureus (ATCC 29213). Two weeks after graft implantation, the pigs were euthanized, and the grafts were surgically excised for clinical, microbiologic, and histopathologic study.

RESULTS

The two bonded grafts treated with S aureus showed no bacterial growth upon explant, whereas the two unbonded grafts treated with S aureus had high bacterial counts (6.25 × 10(6) and 1.38 × 10(7) CFU/graft). The two control grafts (unbonded and untreated) showed bacterial growth (1.8 × 10(3) and 7.27 × 10(3) CFU/graft) that presumably reflected direct, accidental perioperative bacterial contamination; S cohnii ssp urealyticus and S chromogenes, but not S aureus, were isolated. The histopathologic and clinical data confirmed the microbiologic findings. Only pigs that received unbonded grafts showed histopathologic evidence of a perigraft abscess.

CONCLUSIONS

Our results suggest that bonding aortic grafts with this triple antimicrobial combination is a promising method of reducing graft infection resulting from direct postoperative bacterial contamination for at least 2 weeks. Further studies are needed to explore the ability of this novel graft to combat one of the most feared complications in vascular surgery.

ECM-based materials in cardiovascular applications: Inherent healing potential and augmentation of native regenerative processes

The in vivo healing process of vascular grafts involves the interaction of many contributing factors. The ability of vascular grafts to provide an environment which allows successful accomplishment of this process is extremely difficult. Poor endothelisation, inflammation, infection, occlusion, thrombosis, hyperplasia and pseudoaneurysms are common issues with synthetic grafts in vivo. Advanced materials composed of decellularised extracellular matrices (ECM) have been shown to promote the healing process via modulation of the host immune response, resistance to bacterial infections, allowing re-innervation and reestablishing homeostasis in the healing region. The physiological balance within the newly developed vascular tissue is maintained via the recreation of correct biorheology and mechanotransduction factors including host immune response, infection control, homing and the attraction of progenitor cells and infiltration by host tissue. Here, we review the progress in this tissue engineering approach, the enhancement potential of ECM materials and future prospects to reach the clinical environment.

New anti-infective coatings of medical implants

Implantable devices are highly susceptible to infection and are therefore a major risk in surgery. The present work presents a novel strategy to prevent the formation of a biofilm on polytetrafluoroethylene (PTFE) grafts. PTFE grafts were coated with gentamicin and teicoplanin incorporated into different lipid-like carriers under aseptic conditions in a dipping process. Poly-d,l-lactic acid, tocopherol acetate, the diglyceride Softisan 649, and the triglyceride Dynasan 118 were used as drug carriers. The drug release kinetics, anti-infective characteristics, biocompatibility, and hemocompatibility of the coatings developed were studied. All coatings showed an initial drug burst, followed by a low continuous drug release over 96 h. The dimension of release kinetics depended on the carrier used. All coated prostheses reduced bacterial growth drastically over 24 h, even below pathologically relevant concentrations. Different cytotoxic levels could be observed, revealing tocopherol acetate as the most promising biocompatible carrier. A possible reason for the highly cytotoxic effect of Softisan 649 could be assessed by demonstrating incorporated lipids in the cell soma with Oil Red O staining. Tromboelastography studies, enzyme-linked immunosorbent assays, and an amidolytic substrate assay could confirm the hemocompatibility of individual coatings. The development of the biodegradable drug delivery systems described here and in vitro studies of those systems highlight the most important requirements for effective as well as compatible anti-infective coatings of PTFE grafts. Through continuous local release, high drug levels can be produced at only the targeted area and physiological bacterial proliferation can be completely inhibited, while biocompatibility as well as hemocompatibility can be ensured.

Prevention of Staphylococcus aureus graft infection by a new gelatin-sealed vascular graft prebonded with antibiotics

OBJECTIVE

The aim of this study was to evaluate the efficacy of a new gelatin-sealed graft prebonded with two antibiotics in resisting infection with Staphylococcus aureus (S aureus) A980142 after direct bacterial application in a dog model.

METHODS

Twelve 6.0-mm polyester grafts were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into two groups. A test group (n = 6) received experimental antibiotic-bonded gelatin-sealed knitted polyester grafts, loaded with two antibiotics, rifampin and tobramycin. A control group (n = 6) received commercial gelatin-sealed knitted polyester grafts. At the end of graft implantation, 50 mul of a 1.8 x 10(4) CFU/mL S aureus solution were instilled directly over the graft. One week after implantation, grafts were harvested with sterile technique. Quantitative cultures were obtained from all the harvested grafts. The results were expressed as colony-forming units per cm(2) of surface of the graft. Bacteriological study was also performed on various tissue samples. The chi(2) test was used to compare the culture proven infection of control and antibiotics-bonded grafts.

RESULTS

Mean inoculum size was similar in the two groups of dogs. Five of the six control grafts grew S aureus A980142 at the time of graft removal, whereas none of the six antibiotic-bonded gelatin-sealed grafts were infected (P = .0192). None of the organ samples were infected in the group implanted with antibiotic-bonded grafts, whereas 15/34 samples grew S. aureus in the control group.

CONCLUSION

These results indicate that this gelatin sealed graft prebonded with two antibiotics resists infection caused by S aureus graft contamination in a dog model.

Experimental treatment of vascular graft infection due to Staphylococcus epidermidis by in situ replacement with a rifampin-bonded polyester graft

In situ prosthetic graft replacement (ISPGR) of an infected prosthesis raises the risk of recurrent infection in the new graft, especially in cases involving drug-resistant microorganisms. The purpose of this animal study was to evaluate in situ replacement of a vascular graft infected by a highly rifampin-resistant strain of Staphylococcus epidermidis with the use of a rifampin-bonded polyester graft. Antibiotic bonding was obtained by soaking grafts in a high dose of rifampin solution (60 mg/mL). The infrarenal abdominal aorta of 20 dogs was replaced using a polyester prosthesis infected with a highly rifampin-resistant strain of Staphylococcus epidermidis. One week later, the 18 surviving animals were randomized into three groups. Group I (n = 6) did not undergo reoperation. Group II (n = 6) underwent ISPGR using a rifampin-bonded prosthesis. Group III (n = 6) underwent ISPGR using an untreated prosthesis. All surviving animals were killed 28 days after the first procedure. Infectious signs were noted and bacteriological study was carried out on explanted prostheses and various tissue samples. The findings of this experimental study show that soaking a polyester prosthesis in a high-dose rifampin solution can prevent reinfection after in situ replacement of a prosthesis infected by a highly rifampin-resistant Staphylococcus epidermidis.

The prevention and treatment of vascular graft infection with a Triclosan (Irgasan)-bonded Dacron graft: an experimental study in the pig

OBJECTIVES

to evaluate the role of Triclosan (Irgasan(R)) in the prevention of prosthetic graft infection.

MATERIAL AND METHODS

fifty-one pigs were assigned randomly to six groups. Group I (graft) and II (graft and Triclosan) were control groups. Groups III (graft) and IV (grafts and Triclosan) were contaminated with 2 x 10(7)CFU/ml S. aureus. Groups V (graft) and VI (graft and Triclosan) were intraoperatively contaminated with 2 x 10(7)CFU/ml S. aureus and reoperated on after 7 days. Remaining animals were sacrificed on day 28. The end point of the investigation was vascular graft infection, defined as the bacteriological and/or histological proof of infection. Results in both control groups no vascular graft infections were detected in Groups I and II. All of the group III animals presented but none of the group IV developed a graft infection (p <0.02). All of the group V animals presented and 10 of 12 animals developed a graft infection.

CONCLUSION

in this animal model Triclosan bonding appears effective in preventing prosthetic graft infection. However, the in situ replacement of Triclosan-protected grafts was not successful in the treatment of graft infection.

An infection-resistant PTFE vascular graft; spiral coiling of the graft with ofloxacin-bonded PTFE thread

OBJECTIVE

To develop an infection-resistant polytetrafluoroethylene (PTFE) vascular graft for potential clinical use in grafting in sites of bacterial contamination and in replacement of the infected grafts.

SETTING

Experimental study in rabbits.

MATERIALS AND METHODS

An antibiotic ofloxacin (OFLX) was bonded to a sheet of PTFE by impregnation, which was cut and twisted into fine threads. The in-vitro antibacterial activity of OFLX-PTFE thread was determined by measuring the zone of growth inhibition against Escherichia coli. The thread was spirally coiled around a ridged outerwall PTFE to make the OFLX-PTFE graft. OFLX-PTFE graft or control graft was interposed in the inferior vena cava (IVC) of rabbits and the entire graft was covered with fibrin containing a fixed number of E. coli. Three or 7 days after the grafting, the grafts with perigraft tissue were harvested and subjected to bacteriological studies.

RESULTS

In spite of early phase rapid elution of OFLX, a significant antibacterial activity was retained for more than 2 weeks. The antibacterial activity of OFLX-PTFE threads implanted in the subcutaneous space of rabbits decreased to 48% after 24 h and to approximately 1% after a week. The swab culture of all the control grafts was positive, while only one of 13 PTFE-OFLX grafts was positive. The number of viable bacteria in the perigraft tissue of OFLX-PTFE grafts was remarkably low in comparison with that of control grafts. Thus, the OFLX-PTFE grafts exhibited a marked in-vivo antibacterial activity.

CONCLUSION

By a unique method, it was possible to furnish PTFE graft with an excellent infection-resistant property, without affecting the original biological behaviour.

Rifampicin impregnated Dacron grafts: no development of rifampicin resistance in an animal model

AIM

Rifampicin impregnated Dacron grafts have been shown to be effective at preventing vascular graft infection in different animal models. The development of resistance to rifampicin would be a major drawback to the widespread use of such a graft. We aimed to determine how readily this would occur by using a sheep animal model.

METHODS

Under general anaesthetic a 2cm long, 5mm diameter Dacron interposition graft inpregnated with 1.2 mg/ml rifampicin was placed in the left carotid artery. An extreme challenge of methicillin resistant Staphylococcus aureus (MRSA) using an inoculum of 10(9) colony forming units was placed directly onto the graft. The grafts were harvested at 3 weeks and cultures of the graft and tissues were taken. The presence or absence of any abscess formation, anastomotic disruption and graft thrombosis was noted. Any positive growths were identified and if found to be the same as the inoculum, the bacteria were used as the inoculum for another sheep. This was repeated once more. Thus we started with three sheep initially and used a total of nine sheep.

RESULTS

There were no deaths. All grafts were infected with the same MRSA strain, confirmed on phage typing. There were three abscess and one anastomotic disruption. Seven of the grafts were occluded. The minimal inhibitory concentration (MIC) of the infecting inoculum and the bacteria retrieved were determined using the agar dilutional method. The MIC for the three initial inocula was < 0.007 mg/l. All subsequent strains isolated had an MIC of < 0.015 mg/l. This was a difference of one dilution and not significant.

CONCLUSION

There was no development of rifampicin resistance using this animal model.

Treatment of vascular graft infection by in situ replacement with a rifampin-bonded gelatin-sealed Dacron graft

PURPOSE

The purpose of this study was to treat an established prosthetic vascular graft infection by in situ replacement with a rifampin-bonded gelatin-sealed Dacron graft in an animal model.

METHODS

The infrarenal aorta of 18 dogs was replaced with a gelatin-sealed graft contaminated in vitro by soaking it in a solution with Staphylococcus epidermidis. One week later, animals were randomized into three groups. In group I (control, (n = 6), the dogs did not undergo repeat operations. The dogs in groups II and III underwent repeat operation. In these animals the infected grafts were removed for bacteriologic analysis and replaced in situ with one of two types of grafts: group II (n = 6) received an untreated, gelatin-sealed graft; group III (n = 6) received a rifampin-bonded, gelatin-sealed graft. Antibiotic bonding was obtained by soaking grafts for 15 minutes in a 60 mg/ml saline solution of rifampin at 37 degrees C. All 18 dogs received no systemic adjunct antibiotic therapy. Control grafts and replacement grafts were removed 4 weeks after the initial implantation for bacteriologic analysis. When harvested, all the grafts were cut into two fragments, and quantitative bacterial cultures were obtained from all the fragments. Results were expressed as colony-forming units (CFU)/cm2 of graft material.

RESULTS

All 18 initially implanted grafts and all the untreated replacement grafts were grossly infected at the time of removal, whereas all the rifampin-bonded replacement grafts had normal incorporation. None of the rifampin-bonded grafts grew bacteria, whereas all the initially implanted and all the untreated replacement grafts were infected (p < 0.01). Bacterial counts from the infected fragments were similar in control grafts (2.6 +/- 1.9 x 10(6) CFU/cm2), in initially implanted grafts of groups II (9 +/- 1.1 x 10(5) CFU/cm2) and III (1.3 +/- 1.5 x 10(6) CFU/cm2), and in untreated replacement grafts of group II (1.7 +/- 2.5 x 10(6) CFU/cm2). Blood culture results and culture results of liver, spleen, kidney, and lung specimens at the time of sacrifice were negative.

CONCLUSION

This study demonstrates that rifampin-bonded gelatin-sealed Dacron grafts are resistant to infection when used for in situ replacement of an infected graft in the dog.

Fibrin sealant adhesive systems: a review of their chemistry, material properties and clinical applications

Fibrin sealants (FS) are the most successful tissue adhesives to date. They have many advantages over adhesive technologies such as cyanoacrylates and marine adhesives in terms of biocompatibility, biodegradation and hemostasis. There are several commercial products in Europe but none in the United States due to the current regulatory stance against pooled plasma blood products. Blood banks and interested investigators have implemented single- and patient autologous-donor production methods with some success. This article will review the history of FS research and development and describe the chemistry of fibrin(ogen) and the production of commercial and research products. Fibrin sealant and purified fibrin characterization is compared and contrasted. The material and adhesive properties are described, and a survey of the clinical applications in which FS has been used is included as well.