InterGard silver bifurcated graft: Features and results of a multicenter clinical study

A Systematic Review of the Recruitment and Outcome Reporting by Sex and Race/Ethnicity in Stent Device Development Trials for Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Women and racial/ethnic minority groups have been shown to experience poor outcomes after endovascular aortic aneurysm repair (EVAR). One potential reason is the rare inclusion of these populations in initial phases of device development. The objective of this systematic review is to understand enrollment and outcome reporting by sex and race/ethnicity in industry-funded EVAR device development trials.

METHODS

MEDLINE, PubMed, and Embase were searched from inception to January 2022 without language restrictions using the following terminology: "stent", "graft", "endograft", "device", and "abdominal aortic aneurysm" (AAA).

CLINICALTRIALS

gov was also searched from inception to January 2022 for "AAA." Two independent reviewers screened and extracted data. All phase I-III and postmarket evaluation trials that included patients ≥18 years of age, who underwent EVAR were assessed. Participation-to-prevalence ratios (PPRs) were calculated to estimate representation of participants by sex and race/ethnicity in trials compared with their share of disease burden.

RESULTS

Among the 4,780 retrieved articles, 55 industry-funded trials met inclusion criteria for this review. A total of 51 trials (93%) reported enrollment by sex/gender, and only 7 trials (13%) reported enrollment by race/ethnicity of the participants. A median of 19 (interquartile range [IQR]: 4.5, 51) women participants were recruited compared to 171 (IQR: 57, 311.5) men, and 17 (IQR: 7.5, 21.5) racial/minority patients were recruited compared to 241 (IQR: 123, 463.5) White participants. Women represent 16.6% of the disease population, and the median PPR is 0.62 (IQR: 0.42, 0.88), which has remained constant over time (Figure 1). None of the device trials reported outcomes based on sex/gender or race/ethnicity.

CONCLUSIONS

This systematic review highlights the disparities in recruitment and outcome reporting based on sex and race/ethnicity in EVAR device development trials. While most trials may be underpowered to study these differences, recent registry studies show differential outcomes based on sex and race/ethnicity of vascular patients. Therefore, it is imperative to include and report outcomes in these participants, starting from the initial device development phases to improve generalizability of device-use and understand sources of variation in device performance.

Use of a Silver-Impregnated Vascular Graft: Single-Center Experience

INTRODUCTION

Vascular graft infection is a life threatening situation with significant morbidity and mortality. Bacterial graft infection can lead to false aneurysms, bleeding and sepsis. There are a lot of risky situations where grafts can become infected. It is therefore highly desirable to have a vascular graft that is resistant to infection. In this retrospective clinical study, a silver-impregnated vascular graft was evaluated in various indications.

METHODS

Our study included a total of 71 patients who received a silver-impregnated vascular graft during the period from 2013 to 2018. Patients had an aortoiliac localization of vascular graft in 61 cases (86%), and a peripheral localization on the lower limbs in 10 cases (14%). Indications for the use of these special vascular grafts were trophic lesions or gangrene in the lower limbs in 24 cases (34%), suspicious mycotic abdominal aortic aneurysm (mAAA) in 4 cases (5.5%), salmonela aortitis or aneurysms in 4 cases (5.5%), infection of the previous vascular graft in 11 cases (15.5%), other infections in 12 cases (17%), AAA rupture in 10 cases (14%) and other reasons (pre-transplant condition, multiple trauma, graft-enteric fistula) in 6 cases (8.5%). Thirty-day mortality, morbidity, the need for reintervention and amputation, primary and secondary graft patency, and finally the presence of a proven vascular graft infection were evaluated.

RESULTS

The 30-day mortality was 19.7%, and morbidity was 42.2%. The primary patency of the vascular graft was 91.5%. Reoperation was necessary in 10 cases (14%) and amputation was necessary in 10 cases (14%). The median length of hospital stay was 13 days and the mean follow-up period was 48 ± 9 months. During the follow-up period, six patients (8.5%) died from reasons unrelated to surgery or without any relation to the vascular graft. Secondary patency after one year was 88%. Infection of the silver graft was observed in three patients (4.2%).

CONCLUSIONS

Based on our results, the silver graft is a very suitable alternative for solving infectious, or potentially infectious, situations in vascular surgery. In particular, in urgent or acute cases, a silver graft is often the only option.

Clinical Studies Reporting on Vascular Graft Coatings for the Prevention of Aortic Graft Infection: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this study was to investigate the efficacy of vascular graft coatings used in the aortic position to prevent vascular graft infection (VGI).

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines using a pre-registered protocol (CRD42020206436). Eligible studies used a vascular graft coating in the aortic position and reported on VGI. A search was performed in MEDLINE (PubMed), Embase, Web of Science, and the Cochrane Library. Primary outcome parameters were VGI, patency, and mortality. Pooled estimates of VGI were calculated using odds ratio (OR) and 95% confidence intervals (CIs) wherever possible. Quality assessment was performed with the Newcastle-Ottawa Assessment Scale and the Revised Cochrane risk of bias tool for randomised trials.

RESULTS

In total, 6 873 papers were identified. Only eight studies were included. Six of eight studies (75%) reported on known antimicrobial coating strategies such as antibiotics (n = 3) and silver (n = 3). In the other two studies, polymer coated grafts were used. Only three of eight studies compared coated with uncoated grafts (two antibiotic and one silver). Two randomised controlled trials reported on the effect of rifampicin soaked (1 mg/mL) grafts and showed no significant effect in the early (2 months; OR 0.69, 95% CI 0.29 - 1.62) or late (2 years; OR 0.73, 95% CI 0.23 - 2.32) post-operative periods. A retrospective cohort study focusing on the effect of silver coated grafts did not reveal any advantage (OR 0.19, 95% CI 0.02 - 1.64). Two polymer coated grafts were not considered to have a potential benefit in the prevention of VGIs.

CONCLUSION

Clinical studies reporting on the antibacterial effect of vascular graft coatings in the aortic position to prevent VGI are scarce. For silver and antibiotic coatings, no significant protection for VGI was observed. New types of grafts or long acting coating strategies are mandatory to prevent this complication in the future.

How to Prevent Surgical Site Infection in Vascular Surgery: A Review of the Evidence

BACKGROUND

This review aims to identify and review the current evidence for preventing postoperative surgical site infections in abdominal aortic aneurysm surgery or infrainguinal arterial surgery.

METHODS

Extended literature review of clinical trials that examined the prevention of postoperative surgical site infections in abdominal aortic aneurysm or infrainguinal arterial surgery. Searches were conducted on Ovid MEDLINE (1950 - 13 March 2020) using key terms for vascular surgery, surgical site infections and specific preventative techniques. Articles were included if they discussed a relationship between a preventative technique and surgical site infections in abdominal aortic aneurysm or infrainguinal arterial surgery. The GRADE guidelines were used to assess the quality of evidence.

RESULTS

21 techniques and 81 studies were included. Prophylactic antibiotics and negative pressure wound therapy have a high quality of evidence for the prevention of surgical site infections in abdominal aortic aneurysm or infrainguinal arterial surgery. A moderate quality evidence base was identified for gentamicin containing collagen implant (confined to high surgical site infection risk centers). Currently, there is a low or very low quality of evidence to suggest a reduction in the surgical site infection rate for combination therapy, glycaemic control, Methicillin-resistant Staphylococcus aureus screening and absorbable suture. Evidence suggests no beneficial effect for nutritional supplementation, chlorhexidine bath, hair removal therapy, Staphylococcus aureus nasal eradication, cyanoacrylate microsealant, silver grafts, rifampicin bonded grafts, triclosan coated suture and postoperative wound drains. Endoscopic saphenous vein harvest may reduce surgical site infection rate (very low quality of evidence) but may lower long-term patency. Autologous vein grafts may increase surgical site infections (very low quality of evidence) but may provide better long-term patency rates in above-knee infrainguinal bypass surgery. There was no identified evidence for perioperative normothermia, electrosurgical bipolar vessel sealer or Dermabond and Tegaderm for surgical site infection prevention in vascular surgery.

CONCLUSIONS

Prophylactic antibiotics and postoperative negative pressure wound therapy are effective in the prevention of postoperative surgical site infection in abdominal aortic aneurysm or infrainguinal arterial surgery. There exists a significant risk of bias in the literature for many preventative techniques and further studies are required to investigate the efficacy of gentamicin containing collagen implant, and specific combination therapies.

A systematic review of preclinical data regarding commercial silver-coated vascular grafts

OBJECTIVE

Vascular graft infection (VGI) is a serious complication with high mortality and morbidity rates. Several measures could be taken to decrease this risk, including the use of silver-containing vascular grafts. However, to date, no clinical advantages have been reported. This study reviews the outcome of preclinical studies focusing on the role of commercially available silver-coated grafts in the prevention of VGI.

METHODS

A systematic review was performed with a focus on the preclinical role of commercially available silver-coated vascular grafts in the prevention and treatment of VGI. A comprehensive search was conducted in Medline, Embase, and Web of Science.

RESULTS

Nine in vitro and five in vivo studies were included. Two commercial grafts were used (INTERGARD SILVER and Silver Graft). In vitro studies used both gram-positive and gram-negative strains. A positive antimicrobial effect was observed in seven of nine studies (77.8%). A delayed antifungal effect against Candida species was observed in vitro, but disappeared when adding serum proteins. In vivo studies witnessed a microbicidal effect in two out of five studies (40%), but only tested a single causative pathogen (ie, Staphylococcus aureus).

CONCLUSIONS

Both in vitro and in vivo studies demonstrated conflicting and mixed results concerning the antimicrobial efficacy of commercially available silver-containing grafts in the prevention of VGI. In general, the study setup was heterogeneous in the different articles. Given the lack of convincing preclinical evidence and their poor performance in clinical studies, more data are needed at this time to guide the appropriate use of silver grafts.

Efficacy of antiseptic impregnation of aortic endografts with rifampicin compared to silver against in vitro contamination with four bacteria that frequently cause vascular graft infections

OBJECTIVE

This in vitro study investigates the antimicrobial efficacy of impregnation of commercially available aortic endografts (EG) with rifampicin (RIF) and nanocolloidal silver.

METHODS

Endografts were flushed with 50 mL of RIF 600 mg, 70 mL of a silver-based aqueous solution (AG), or 50 mL of phosphate-buffered saline (PBS) over 15 minutes. Endografts were then retrieved from the sheath and cut in 1 × 1 cm sized graft units (n = 80 of each impregnation), which were then incubated for 1 hour separately with inoculates containing 10⁶ or 10³ bacteria per milliliter (bact/mL) of each of the following bacteria: Staphylococcus epidermidis, Escherichia coli, multisensitive Staphylococcus aureus, and Pseudomonas aeruginosa. After sonication of the graft units, bacterial counts were measured by plating out twice the sonication solution on Mueller-Hinton plates.

RESULTS

RIF showed a statistically significant decrease of colony forming units per milliliter for all four bacterial strains in both concentrations compared with PBS and AG, except for 10³ bact/mL of E coli. AG showed a significant decrease of colony forming units per milliliter compared with PBS only for 10⁶ bact/mL of E coli and was statistically significantly inferior to RIF for all four bacterial strains in both concentrations with the exception of E coli at a concentration of 10³ bact/mL.

CONCLUSIONS

This in vitro study demonstrated infectivity resistance of aortic EG after flushing with RIF. Moreover, the feasibility of flushing aortic EG with a new silver-based agent could be demonstrated, but without statistically significant antimicrobial efficacy compared with native EG.

Single and multi-functional coating strategies for enhancing the biocompatibility and tissue integration of blood-contacting medical implants

Device-associated clot formation and poor tissue integration are ongoing problems with permanent and temporary implantable medical devices. These complications lead to increased rates of mortality and morbidity and impose a burden on healthcare systems. In this review, we outline the current approaches for developing single and multi-functional surface coating techniques that aim to circumvent the limitations associated with existing blood-contacting medical devices. We focus on surface coatings that possess dual hemocompatibility and biofunctionality features and discuss their advantages and shortcomings to providing a biocompatible and biodynamic interface between the medical implant and blood. Lastly, we outline the newly developed surface modification techniques that use lubricant-infused coatings and discuss their unique potential and limitations in mitigating medical device-associated complications.

Synthesis of Calix-Salen Silver Corates for Evaluation of Their Antimicrobial and Anticancer Activities

Silver-based products are becoming popular as antimicrobial agents because of the failure of antibiotics available for tackling the drug-resistant microbial strains. As silver is well tolerated by normal human cells, silver complexes have emerged as important antineoplastic agents. Further, if silver ions are encapsulated within an organic molecule-an azacorand-it may serve as a better substitute for cisplatin or other metal complexes. The calix-salen-type corates were synthesized using silver ions as the template. 5,5'-methylene-bis-salicylaldehyde was reacted with ethylene diamine in methanol at room temperature in the presence of silver nitrate. The resultant corand trapped the silver template in their cavity. The electron-withdrawing and electron-releasing groups like -NO₂, -Br, -C(CH₃)₃, and -OCH₃ were substituted on the bis-aldehyde to study their effects on the antimicrobial and anticancer activities of silver corates. The silver corates were found to have better antimicrobial activity than some of the standard drugs. Bromo-substituted corate-3, nitro-substituted corate-4, and tert-butyl-substituted corate-5 were found to be potent antibacterial agents among all. The bromo-substituted corate-3 was found to be the most potent fungicidal agent among all silver corates. The result of antineoplastic activity suggests that unsubstituted corate-1 and bromo-substituted corate-3 are potential candidates to be used as therapeutic molecules for cancer treatment, which requires further validation.

Aortic treatment of native infection by reconstruction with the Omniflow II biologic prosthesis

Aortic infection is a challenging condition. Fortunately, surgical revision of infected aorta with in situ reconstruction can provide long-term cure. The material for aortic repair remains an area of debate. The Omniflow II (LeMaitre Vascular, Burlington, Mass) prosthesis is a biosynthetic graft made to resist long-term degeneration and allows growth of host tissue with reduction of the risk of arterial infection. It has already been used for peripheral bypass with very low infection rates. Herein, we describe an original case of first-line native aorta replacement by a straight Omniflow II biologic prosthesis for infected aortic aneurysm.

Silver particle monolayers — Formation, stability, applications

The formation of silver particle monolayers at solid substrates in self-assembly processes is thoroughly reviewed. Initially, various silver nanoparticle synthesis routes are discussed with the emphasis focused on the chemical reduction in aqueous media. Subsequently, the main experimental methods aimed at bulk suspension characterization are critically reviewed by pointing out their advantages and limitations. Also, various methods enabling the in situ studies of particle deposition and release kinetics, especially the streaming potential method are discussed. In the next section, experimental data are invoked illustrating the most important features of particle monolayer formation, in particular, the role of bulk suspension concentration, particle size, ionic strength, temperature and pH. Afterward, the stability of monolayers and particle release kinetics are extensively discussed. The results obtained by the ex situ AFM/SEM imaging of particles are compared with the in situ streaming potential measurements. An equivalency of both methods is demonstrated, especially in respect to the binding energy determination. It is shown that these experimental results can be adequately interpreted in terms of the hybrid theoretical approach that combines the bulk transport step with the surface blocking effects derived from the random sequential adsorption model. It is also concluded that the particle release kinetics is governed by the discrete electrostatic interactions among ion pairs on particle and substrate surfaces. The classical theories based on the mean-field (averaged) zeta potential concept proved inadequate. Using the ion pair concept the minor dependence of the binding energy on particle size, ionic strength, pH and temperature is properly explained. The final sections of this review are devoted to the application of silver nanoparticles and their monolayers in medicine, analytical chemistry and catalysis.

Aortic graft in hollow viscus

Secondary aortoenteric fistulas (AEFs) and aortic graft infection are relatively rare but fatal complications of aortic surgery. A 77-year-old man had a 1-week history of fever and abdominal pain with right inguinal area swelling. The patient's medical history included hypertension, aortobifemoral bypass grafting due to right iliac artery, and superficial femoral artery occlusion. Abdominopelvic computed tomography revealed the presence of an aortic graft in the hollow viscus. Although there have been several reports of secondary AEF, there have been few reports of an aortic graft in a hollow viscus. Diagnosis of AEF can be delayed in patients with atypical symptoms. Without a high index of suspicion, this condition has fatal consequences.

Results from the International Silver Graft Registry for high-risk patients treated with a metallic-silver impregnated vascular graft

The purpose of this postmarket surveillance registry was to document the efficacy of a vascular prosthesis coated with metallic silver in high-risk patients undergoing vascular reconstructions. Patency (primary endpoint) and freedom from graft infection (secondary endpoint) data were assessed at a minimum of 12 months in patients with significant co-morbidity and/or confirmed graft infections or infected native vessels. Between November 2006 and December 2009, 230 patients with high-risk factors underwent aortic, peripheral and/or extra-anatomic reconstructions with Silver Graft® (SG) in six German, one French and one Polish vascular center. All participating centers used the metallic silver-coated polyester graft (SG) in various diameters and lengths including tubular and bifurcate vascular grafts. Doppler ultrasound follow-ups to determine graft patency were planned at 12 months or done at an earlier time in case the patient became symptomatic. A total of 230 patients were studied. Ten of these 230 patients had graft infections at baseline whereas the remaining 220 subjects had significant risk factors such as coronary artery disease (62.7%, 138/220), vascular access in scar tissue (27.3%, 60/220), Fontaine III/IV (38.2%, 84/220), chronic renal insufficiency (26.8%, 59/220) and diabetes (21.0%, 46/220). The long-term follow-up at 15.5 ± 8.3 months revealed a secondary patency rate of 93.2% (205/220) and an ‘all cause’ mortality rate of 18.6% (41/220). There was a freedom from de novo graft infection rate of 95.9% (211/220) in the high-risk group without graft infections at baseline. One regraft infection occurred distal of the revisional reconstruction in the 10 patients with graft infection at baseline. The presence of perigraft fluid at follow-up and Fontaine III/IV at baseline were found to be predictors for graft patency whereas perigraft fluid presence was the only predictor for de novo graft infections. This registry revealed favorable patency and freedom from de novo infections rates in a ‘high-risk’ population with significant co-morbidities.

Laminar flow reduces cases of surgical site infections in vascular patients

Introduction

Numerous strategies are employed routinely in an effort to lower rates of surgical site infections (SSIs). A laminar flow theatre environment is generally used during orthopaedic surgery to reduce rates of SSIs. Its role in vascular surgery, especially when arterial bypass grafts are used, is unknown.

Methods

A retrospective review of a prospectively maintained database was undertaken for all vascular procedures performed by a single consultant over a one-year period. Cases were performed, via random allocation, in either a laminar or non-laminar flow theatre environment. Demographic data, operative data and evidence of postoperative SSIs were noted. A separate subgroup analysis was undertaken for patients requiring an arterial bypass graft. Univariate and multivariate logistical regression was undertaken to identify significant factors associated with SSIs.

Results

Overall, 170 procedures were analysed. Presence of a groin incision, insertion of an arterial graft and a non-laminar flow theatre were shown to be predictive of SSIs in this cohort. In the subgroup receiving arterial grafts, only a non-laminar flow theatre environment was shown to be predictive of an SSI.

Conclusions

This study suggests that laminar flow may reduce incidences of SSI, especially in the subgroup of patients receiving arterial grafts.

Clinical profile of aortoiliac occlusive disease and outcomes of aortobifemoral bypass in India

OBJECTIVE

Aortoiliac arterial occlusive (AIOD) disease is common in India. The clinical presentation and etiology are different than in the West. Intervention is frequently required for advanced lower extremity ischemia, but the results have not been systemically evaluated. We studied the clinical profile and midterm results of patients undergoing aortobifemoral bypass for AIOD at a tertiary care center in south India.

METHODS

Clinical data of patients undergoing aortobifemoral bypass for AIOD over a 6-year period from January 1, 2005 to December 31, 2010 were retrospectively analyzed. Clinical presentation and factors affecting outcome were evaluated. Graft patency and mortality were included as study end points.

RESULTS

Ninety-nine patients (mean age, 52 years) with AIOD who underwent aortobifemoral bypass were included. Etiology included atherosclerosis in 79 patients, thromboangiitis obliterans in 15, Takayasu's arteritis in two, and hematological conditions in 3. Smoking (82%), hypertension (40%), and diabetes (30%) were the most common risk factors; ischemic heart disease (4%), obesity (2%), and dyslipidemia (3%) were rare. Eighty-one percent of patients presented with critical limb ischemia. Mean duration of symptoms was 22 months (range, 4 months to 9 years). Concomitant infrainguinal arterial occlusive disease was identified in 81%, but intervened upon in only 2%. In-hospital mortality was 3%. Causes of death included myocardial infarction in two and colon ischemia in one. Major morbidity included nonfatal myocardial infarction (3%), pneumonia/atelectasis (5%), and renal dysfunction (2%). Groin wound complications occurred in 20%, seroma/lymph leak in 13%, infection in 7%, and anastomotic hemorrhage in 2%. Multidrug-resistant and polymicrobial infections were common. Early graft thrombosis (30 days) occurred in 15 patients; 8 of 11 reintervened grafts were salvaged. Four more grafts thrombosed during a mean follow-up of 2 years (range, 0-5 years) and two became infected. Overall study major limb loss rate was 10% (primary, 2%; secondary, 8%). Delayed presentation and smoking were more common in patients developing complications. There was no significant difference in overall complication rates between patients with thromboangiitis obliterans and atherosclerosis (P = .66).

CONCLUSIONS

Despite earlier age at presentation, atherosclerosis remains the predominant etiology of aortoiliac arterial occlusive disease in Indian patients. Results of open revascularization are comparable to those in the Western literature. Thromboangiitis obliterans is the underlying pathology in a minority of patients with no significant difference in operative outcome. Patients frequently present late with critical limb ischemia, but this does not affect outcome.

Use of silver in the prevention and treatment of infections: silver review

BACKGROUND

The use of silver for the treatment of various maladies or to prevent the transmission of infection dates back to at least 4000 b.c.e. Medical applications are documented in the literature throughout the 17th and 18th centuries. The bactericidal activity of silver is well established. Silver nitrate was used topically throughout the 1800 s for the treatment of burns, ulcerations, and infected wounds, and although its use declined after World War II and the advent of antibiotics, Fox revitalized its use in the form of silver sulfadiazine in 1968.

METHOD

Review of the pertinent English-language literature.

RESULTS

Since Fox's work, the use of topical silver to reduce bacterial burden and promote healing has been investigated in the setting of chronic wounds and ulcers, post-operative incision dressings, blood and urinary catheter designs, endotracheal tubes, orthopedic devices, vascular prostheses, and the sewing ring of prosthetic heart valves. The beneficial effects of silver in reducing or preventing infection have been seen in the topical treatment of burns and chronic wounds and in its use as a coating for many medical devices. However, silver has been unsuccessful in certain applications, such as the Silzone heart valve. In other settings, such as orthopedic hardware coatings, its benefit remains unproved.

CONCLUSION

Silver remains a reasonable addition to the armamentarium against infection and has relatively few side effects. However, one should weigh the benefits of silver-containing products against the known side effects and the other options available for the intended purpose when selecting the most appropriate therapy.

Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir-Blodgett films

Silver complexes of a cation binding supramolecular host, resorcinarene bis-crown (CNBC5) with propyl, nonyl, decyl and undecyl alkyl chains were investigated by NMR titration, picrate extraction and single crystal X-ray diffraction. Binding studies showed that both 1 : 1 and 1 : 2 (host-Ag(+)) complexes are present in solution with only a slight effect of the lower rim alkyl chain length on the binding constants (log K 4.0-4.2 for 1 : 2 complexes). Solid state complexes of the resorcinarene bis-crowns bearing either C(3) or C(11) chains were obtained. Single crystal X-ray analyses showed that both derivatives bind silver ions by metal-arene and Ag···O coordination from the crown ether bridges and from the solvent, and pack in layered or bilayered fashion. Furthermore, the amphiphilic nature of C11BC5 was demonstrated using the Langmuir balance technique. Langmuir-Blodgett films of the amphiphilic C11BC5-Ag complex were transferred onto a substrate and shown to possess antibacterial activity against E. coli.

Applications of nanotechnology in food packaging and food safety: barrier materials, antimicrobials and sensors

In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.

Surgical outcome in patients with concomitant-infected abdominal aortic aneurysm and spondylitis

The coexistence of infected abdominal aortic aneurysms and spondylitis is rare but challenging. The etiology of the infection is frequently unknown. The aim of this study was to review the outcome of surgical repair of this complex disease. From 2004 to 2006, six patients were identified who underwent surgical repair of concomitant infected abdominal aortic aneurysm and spondylitis. Diagnosis, treatment and intermediate-term results are presented. The clinical manifestation included the signs of ongoing systemic infection, neurological deficit and abdominal or back pain. Computed tomography revealed abdominal aortic aneurysms associated with polysegmental spondylitis. Patients underwent radical debridement and aortic replacement with cryopreserved aortic allografts or silver-coated prostheses followed by antibiotic treatment. Only one patient received a simultaneous anterior vertebral stabilization. Greater omentum was placed in the abscess cavity. Intensive care unit and hospital stay averaged 3.0 and 28.0 days, respectively. Organisms were identified in all but one patient. Over a follow-up period of 4.4 years, four patients are alive and showing freedom from infection, and two patients had died unrelated at seven and eight months. In conclusion, surgical repair of infected aortic aneurysms with resection of infected tissues and implantation of a homograft or a silver-coated prosthesis achieved favorable results in this sick patient group. Simultaneous vertebral stabilization is rarely necessary.

[Mid-term results of silver-coated Dacron graft implantation in aortic and lower extremity revascularization]

BACKGROUND

Prosthetic graft infection or the need for reconstructive arterial surgery in septic condition is a challenging situation in vascular surgery. Recent introduction of silver coated polyester graft has meant a new therapeutic option in selecting the type of graft for revascularization. In this study we analyzed the short and midterm outcome of using silver coated grafts in aortic and lower extremity arterial reconstructions (mortality, graft occlusion, graft infection, amputation).

MATERIALS AND METHODS

In a single center retrospective study we implanted 42 silver coated Dacron grafts (InterGard Silver Dacron prosthesis). The indication of silver graft implantation was graft infection in 17, aorto-duodenal fistula in 7, septic condition caused by gangrene in 16 cases and in 2 cases infection was not established.

RESULTS

Forty silver grafts were implanted in 40 patients with diagnosed infection. The mean age was 62 years (35-81 years), 70% were men. Long term follow-up data were available in 29 patients; the mean follow-up time was 36.76 months. Early (within 30 days of surgery) death occurred in 3 and late death in 11 cases (8 and 38%). Early graft occlusion was noticed in 8 and late occlusion in 2 cases (20 and 7%). Reinfection was diagnosed in 7% of the cases in the early and the midterm period as well. Eight amputations were indicated in the early postoperative period (5 major and 3 minor) and 28% of the patients required major amputation during the follow-up.

CONCLUSIONS

Silver coated Dacron graft means a valuable therapeutic option with good rate of infection control in the treatment of graft infection and septic condition in the lack of autologous graft material in this high risk population.

In vivo detection of Staphylococcus aureus in biofilm on vascular prostheses using non-invasive biophotonic imaging

OBJECTIVES

Biophotonic imaging was compared to standard enumeration method both for counting Staphylococcus aureus in biofilm and bacterial susceptibility tests of different graft materials.

DESIGN

Prospective, randomized, controlled animal study.

MATERIAL AND METHODS

Five types of vascular grafts were placed subcutaneously in 35 mice and challenged with bioluminescent S. aureus. The mice were divided into equal groups as follows: group A (polyester), group B (polytetrafluoroethylene), group C and D (two types of silver acetate-coated polyester) and group E (bovine pericardium). Controls were given only the bacteria. The bioluminescence signal of S. aureus, able to predict number of viable bacteria in biofilm without any manipulation, was measured at different time points. Five days postinfection, regular cultures of adherent bacteria on grafts were obtained. Comparative analyses between bioluminescence activity and culture enumeration were performed.

RESULTS

The number of viable bacteria on silver-coated prostheses was the slightest, indicating superior bacterial resistance. The density of bacteria on polytetrafluoroethylene and polyester was comparable, with a non-significant advantage for polytetrafluoroethylene. Moreover, bioluminescence detected the number of viable S. aureus in biofilm more exactly compared to enumeration of bacteria.

CONCLUSION

Bioluminescence imaging can be considered a useful tool to characterize susceptibility of any graft material to bacterial biofilm prior to implantation.

Infected aneurysm of the aortic arch with purulent pericarditis caused by Streptococcus pneumoniae

A 76-year-old woman had a chest pain and high fever, and was admitted to the intensive care unit diagnosed as acute pericarditis. Enhanced CT-scan showed a 47-mm aneurysm in the aortic arch which seemed to be impending rupture and the part of the aorta looked like a pseudoaneurysm. Emergent total aortic arch replacement with a rifampicin-bonded Dacron graft was performed. Pericardial effusion was purulent and the aorta was infected with pus discharge in the aortic wall. There were some ulcerations on the surface of the luminal wall of the aorta. One of them was penetrating into the pericardial space causing a pseudoaneurysm. Both pericardial effusion and excised aortic wall were sent to culture study and resulted in positive for Streptococcus pneumoniae. The infection of the aorta, with erosion into the pericardial space, seemed to be the cause of purulent pericarditis. Antibiotic therapy was commenced immediately after surgery and continued for four weeks. Though she had neurological deficit after surgery, her infection was well controlled and there was no recurrence of infection 11 months after surgery.

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.