Vascular graft infections:

Deciphering Key microRNA Regulated Pathways in Tissue-Engineered Blood Vessels: Implications for Vascular Scaffold Production

MicroRNAs (miRNAs) are non-coding RNAs involved in the regulation of gene expression associated with cell differentiation, proliferation, adhesion, and important biological functions such as inflammation. miRNAs play roles associated with the pathogenesis of chronic degenerative disorders including cardiovascular diseases. Understanding the influence of miRNAs and their target genes can effectively streamline the identification of key biologically active pathways that are important in the development of vascular grafts through the tissue engineering of blood vessels. To determine miRNA expression levels and identify miRNA target genes and pathways with biological roles in scaffolds that have been repopulated with adipose-derived stem cells (ASCs) generated through tissue engineering for the construction of blood vessels. miRNA quantification assays were performed in triplicate to determine miRNA expression in a total of 20 samples: five controls (natural inferior vena cava), five scaffolds recellularized with ASCs and differentiated into the endothelium (luminal layer), five samples of complete scaffolds seeded with ASCs differentiated into the endothelium (luminal layer) and smooth muscle (extraluminal layer), and five samples of ASC without cell differentiation. Several differentially expressed miRNAs were identified and predicted to modulate target genes with roles in key pathways associated with angiogenesis, vascular system control, and endothelial and smooth muscle regulation, including migration, proliferation, and growth. These findings underscore the involvement of these pathways in the regulatory mechanisms that are essential for vascular scaffold production through tissue engineering. Our research contributes to the knowledge of miRNA-regulated mechanisms, which may impact the design of vascular substitutes, and provide valuable insights for enhancing clinical practice. The molecular pathways regulated by miRNAs in tissue engineering of blood vessels (TEBV) allowed us to elucidate the main phenomena involved in cellular differentiation to constitute a blood vessel, with the main pathways being essential for angiogenesis, cellular differentiation, and differentiation into vascular smooth muscle.

Actinomyces spp. Prosthetic Vascular Graft Infection (PVGI): A Multicenter Case-Series and Narrative Review of the Literature

BACKGROUND

Actinomycosis represents a challenging and under-reported complication of vascular surgery. Optimal management of Actinomyces spp. prosthetic vascular graft infection (PVGI) is highly uncertain because of the paucity of reports on this disease.

METHODS

We conducted a retrospective case-series of Actinomyces-PVGI that occurred in the last five years in two major university hospitals in northern Italy. We searched for previously published cases in the scientific literature.

RESULTS

We report five original cases of Actinomyces spp. prosthetic vascular graft infection following aortic aneurysm repair. Our literature review retrieved eight similar cases. Most patients were immunocompetent males. Most infections were polymicrobial (11/13 cases), with a prevalence of A. odontolyticus involvement (3/13 cases were associated with. Salmonella spp. infection). All cases had a late presentation (≥4 months from graft placement), with 61% associated with an aorto-enteric fistula. All patients received antibiotic therapy, but the duration was highly heterogeneous (from two weeks to life-long antibiotics). The patients without surgical revision experienced septic recurrences (2/13), permanent dysfunction (1/13), or a fatal outcome (2/13), while of the remainder who underwent vascular graft explant, six recovered completely and one developed a periprosthetic abscess. In two cases follow-up was not available.

CONCLUSIONS

This case-series aims to raise the diagnostic suspicion and to describe the current management of Actinomyces-PVGIs. We highlight a high heterogeneity in antibiotic duration, choice of the antibiotic regimen, and surgical management. Higher reporting rate is advisable to produce better evidence and optimize management of this rare complication of vascular surgery.

Case report: Analysis of phage therapy failure in a patient with a Pseudomonas aeruginosa prosthetic vascular graft infection

Clinical case of a patient with a Pseudomonas aeruginosa multidrug-resistant prosthetic vascular graft infection which was treated with a cocktail of phages (PT07, 14/01, and PNM) in combination with ceftazidime-avibactam (CZA). After the application of the phage treatment and in absence of antimicrobial therapy, a new P. aeruginosa bloodstream infection (BSI) with a septic residual limb metastasis occurred, now involving a wild-type strain being susceptible to ß-lactams and quinolones. Clinical strains were analyzed by microbiology and whole genome sequencing techniques. In relation with phage administration, the clinical isolates of P. aeruginosa before phage therapy (HE2011471) and post phage therapy (HE2105886) showed a clonal relationship but with important genomic changes which could be involved in the resistance to this therapy. Finally, phenotypic studies showed a decrease in Minimum Inhibitory Concentration (MIC) to ß-lactams and quinolones as well as an increase of the biofilm production and phage resistant mutants in the clinical isolate of P. aeruginosa post phage therapy.

Infection of Vascular Prostheses: A Comprehensive Review

Vascular graft or endograft infection (VGEI) is a complex disease that complicates vascular-surgery and endovascular-surgery procedures and determines high morbidity and mortality. This review article provides the most updated general evidence on the pathogenesis, prevention, diagnosis, and treatment of VGEI. Several microorganisms are involved in VGEI development, but the most frequent one, responsible for over 75% of infections, is Staphylococcus aureus. Specific clinical, surgical, radiologic, and laboratory criteria are pivotal for the diagnosis of VGEI. Surgery and antimicrobial therapy are cornerstones in treatment for most patients with VGEI. For patients unfit for surgery, alternative treatment is available to improve the clinical course of VGEI.

Vascular Graft Infection Imaging

Vascular graft infection is a rare, life threatening complication of vascular repair with synthetic or native material. The pathogenesis, causative microorganisms and clinical manifestations vary according to graft's location and time duration since surgery. The diagnosis of graft infection is challenging since there is no single "gold standard" test and diagnosis is based on clinical and radiological criteria. Early and accurate diagnosis are essential for patient management and prevention of further complications. The first-choice imaging modality is computed tomography angiography (CTA) that can demonstrate typical signs of graft infection but has limited sensitivity and specificity, especially in early and low-grade infections. Nuclear medicine imaging methods, including labeled white blood cell scintigraphy and FDG PET/CT demonstrate improved diagnostic accuracy and play a pivotal role in the diagnosis of vascular graft infection. The different radiologic and the nuclear medicine imaging techniques, their advantages and limitations, and the recent guidelines detailing their use are reviewed.

Thoracic aortic vascular graft infection: outcome after conservative treatment without graft removal

OBJECTIVES

Surgical debridement with aortic graft removal is considered the preferred treatment for thoracic aortic vascular graft infection (VGI). Conservative treatment with antibiotics only is usually reserved for inoperable patients. Due to Outpatient Parenteral Antimicrobial Therapy (OPAT) and better understanding of the antibiotic impact on biofilms, long-term targeted antibiotic therapy without graft removal may be an alternative treatment option for selected thoracic aortic VGI patients. The aim of this case series was to evaluate the outcome in patients with thoracic aortic VGI who were treated without graft removal.

METHODS

This single-centre retrospective cohort study evaluated patients with a thoracic aortic VGI diagnosed between 2008 and 2021 and who were treated without graft removal. The primary outcome parameter was the 6-month mortality rate after VGI diagnosis. Secondary outcome parameters were cure rates and relapse of infection.

RESULTS

Twenty-four patients with thoracic aortic VGI who were managed without graft removal were identified. The mortality rate 6 months after VGI diagnosis was 8% (2/24); one of these deaths was infection related. The median antibiotic treatment duration was 13 months (interquartile range 15). A total of 16 patients (67%) were cured. No relapses occurred after a median of 24-month (interquartile range 32) follow-up.

CONCLUSIONS

Intensive antibiotic treatment, without graft removal, may be a non-inferior option in patients with a thoracic aortic VGI who are not considered for surgery.

Diagnostic accuracy of FDG PET for the identification of Vascular Graft Infection

BACKGROUND

Fluorodeoxyglucose (FDG) positron emission tomography (FDG PET/CT) can be used to identify and localize infection in patients with vascular graft infections (VGI). We aimed to evaluate the diagnostic accuracy of 18F-FDG PET/CT by defining thresholds for standardized uptake value (SUV) and tissue-to-background ratio (TBR) that would accurately identify the presence of vascular graft infection.

METHODS

Patients with suspected VGI were prospectively recruited and underwent 18F-FDG PET/CT scans. Diagnosis was based on clinical, laboratory and radiologic findings, and blinded to the results of the PET/CT scan. Receiver operator characteristics (ROC) curve analysis was done to determine optimal thresholds for SUV and TBR.

RESULTS

Our final cohort consisted of 28 patients with suspected VGI (mean±SD age 67±10 years, 61% men), of which 15 patients (54%) had definitive VGI. The cohort included 61% prosthetics grafts and 39% stent-grafts. The type of graft included in this study were biologic (4%), Dacron (64%) and Polytetrafluoroethylene (32%). The location of the implanted grafts were aortic (54%) and peripheral arterial reconstruction (46%). The location of the peripheral graft was 77% in lower extremity and 23% in the upper extremity (arterio-venous grafts for dialysis access). Using ROC analysis, SUV max of 4.5, SUV mean of 3.7, and a TBR of 1.6 gave the best balance between sensitivity and specificity (93%/92%, 100%/92% and 93%/92% respectively). All thresholds had an area under the curve ≥0.93 and correct reclassification rate ≥93%.

CONCLUSION

Our data suggests that FDG PET/CT can be used to reliably and accurately diagnose VGI. The dual anatomic-physiologic information from FDG PET/CT can complement clinical diagnosis particularly in uncertain cases.

Echocardiography and FDG-PET/CT scan in Gram-negative bacteremia and cardiovascular infections

PURPOSE OF REVIEW

Current evidence on cardiovascular infections in Gram-negative blood stream infections (GNBSI) with focus on the use of transesophageal echocardiography (TEE) and 18F-Fluorodeoxyglucose - positron emission tomography/Computed tomography (FDG-PET/CT) in the diagnostic workup.

RECENT FINDINGS

Most evidence focuses on characteristics of diagnosed cardiovascular infections and the proportion caused by GNBSI. These proportions are low (1-5%) when it comes to native and prosthetic valve endocarditis as well as cardiac implantable electronic device (CIED) infections whereas the proportion of vascular graft infections caused by GNBSI seems substantially higher (30-40%). Information on the prevalence of cardiovascular infection in patients with GNBSI is limited to a few studies finding around 3% endocarditis in patients with GNBSI and a prosthetic heart valve and 4-16% device-related infection in patients with CIED and GNBSI.

SUMMARY

Patients with GNBSI and native or prosthetic valves should only undergo work-up for endocarditis (TEE and FDG-PET/CT) if they present GNBSI relapse or signs suggestive of endocarditis. CIED patients with GNBSI with Pseudomonas or Serratia spp. should undergo TEE and PET/CT because of the high prevalence of device-related infection. In other GNBs without IE suggestive signs, normal BSI treatment is reasonable and only cases with relapse need work-up. GNBSI in patients with vascular grafts should lead to consideration of PET/CT.

Use of rifampicin and graft removal are associated with better outcomes in prosthetic vascular graft infection

OBJECTIVES

Prosthetic vascular graft infection (PVGI) is a very severe disease. We aimed to determine the factors associated with treatment failure.

METHODS

Patients admitted to two University Hospitals with PVGI were included in this retrospective study. PVGI was classified as possible, probable or proven according to an original set of diagnostic criteria. We defined treatment failure if one of the following events occurred within the first year after PVGI diagnosis: death and infection recurrence due to the same or another pathogen.

RESULTS

One hundred and twelve patients were diagnosed with possible (n = 26), probable (n = 22) and proven (n = 64) PVGI. Bacterial documentation was obtained for 81% of patients. The most frequently identified pathogen was Staphylococcus aureus (n = 39). Surgery was performed in 96 patients (86%). Antibiotics were administered for more than 6 weeks in 41% of patients. Treatment failure occurred in 30 patients (27.5%). The factors associated with a lower probability of treatment failure were total removal of the infected graft (OR = 0.2, 95% CI [0.1-0.6]), rifampicin administration (OR = 0.3 [0.1-0.9]) and possible PVGI according to the GRIP criteria (OR = 0.3 [0.1-0.9]).

CONCLUSIONS

Treatment failure occurred in 27.5% of patients with PVGI. Total removal of the infected graft and rifampicin administration were associated with better outcomes.

A Scoping Review on the Use of Antibiotic-Impregnated Beads and Applications to Vascular Surgery

INTRODUCTION

Surgical site infection (SSI) presents a ubiquitous concern to surgical specialties, especially in the presence of prosthetic material. Antibiotic-impregnated beads present a novel and evolving means to combat this condition. This review aims to analyze the quality of evidence and methods of antibiotic bead use, particularly for application within vascular surgery.

METHODS

A systematic scoping review was conducted within Embase, MEDLINE, and the Cochrane Registry of Randomized Controlled Trials. Articles were evaluated by 2 independent reviewers. Level of evidence was evaluated using the Oxford Center for Evidence-Based Medicine Criteria and the Cochrane Risk of Bias Tool for Randomized Controlled Trials.

RESULTS

The search yielded 6951 papers, with 275 included for final analysis. Publications increased in frequency from 1978 to the present. The most common formulation was polymethyl methacrylate; however publications on biodegradable formulations, including calcium sulfate beads, have been published with increasing frequency. Most publications had positive conclusions (94.2%); however, the data was mainly subjective and may be prone to publication bias. Only 11 randomized controlled trials were identified and all but one was evaluated to be at a high risk of bias. The most common indication was for osteomyelitis (52%), orthopedic prosthetic infections (20%), and trauma (9%). Within vascular surgery, beads have been used primarily for the treatment of graft infection, with freedom from recurrence rates being reported from 41% to 87.5%.

CONCLUSIONS

Antibiotic-impregnated beads provide a means to deliver high doses of antibiotic directly to a surgical site, without the risks of parenteral therapy. There has yet to be significant high-level quality data published on their use. There is a large body of evidence that suggests antibiotic beads may be used in SSIs in high-risk patients, prosthetic infections, and other complex surgical infections. Important potential areas of application in vascular surgery include graft infection, prevention of wound infection in high-risk patients, and diabetic foot infection.

Negative pressure wound therapy with intermittent instillation of rifampin for the treatment of an infected vascular bypass graft

Negative pressure wound therapy with intermittent instillation, especially with the addition of antibiotics in the case of infection, is a versatile treatment modality for the closure of wounds and can be used both primarily after débridement and secondarily after failure of muscle flap coverage. We present a case in which negative pressure wound therapy with intermittent instillation of rifampin was used to successfully close a groin wound secondary to an infected prosthetic vascular graft that initially failed to close with a muscle flap. Consideration of this approach to wound closure and graft salvage is important because of the seriousness and relatively common incidence of prosthetic vascular graft infection after infrainguinal arterial bypass revascularization.

Life-long antimicrobial therapy: where is the evidence?

The decision to prescribe long-term or 'life-long' antibiotics in patients requires careful consideration by the treating clinician. While several guidelines exist to help assist in this decision, the long-term consequences are yet to be well studied. In this review, we aim to provide a summary of the available evidence for patient populations where long-term antibiotic therapy is currently recommended in clinical practice. We will also discuss the pitfalls of this approach, including medication adverse effects, economic cost and any possible contribution to the emerging epidemic of microbial resistance.

Early Onset of Acute Lower Limb Drug-eluting Stent Infection

The present case describes acute and early infection of a superficial femoral artery drug-eluting stent (DES) in a 65-year-old patient 2 days after its implantation in outpatient clinic, with intense clinical presentation. The initial indication was Rutherford 3 peripheral artery disease. Radical treatment by means of stent explantation and femoro-femoral bypass using autogenous vein was performed. Both stent and blood cultures were positive for methicillin-sensitive Staphylococcus aureus. Informative imaging and intraoperative view are provided. Local evolution was satisfactory but endocarditis occurred secondarily. The pathophysiology of this first reported DES infection and the management of the infected vessel are discussed, in light of data derived from coronary literature and open vascular surgery.

A systematic review and meta-analysis of 18F-fluorodeoxyglucose positron emission tomography or positron emission tomography/computed tomography for detection of infected prosthetic vascular grafts

OBJECTIVE

The purpose of this investigation was to evaluate the diagnostic accuracy of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) or PET/computed tomography (PET/CT) for the detection of vascular prosthetic graft infection (VPGI) using a diagnostic accuracy test.

METHODS

The MEDLINE/PubMed and Embase databases, from the earliest available date of indexing through March 31, 2018, were searched for results investigating the diagnostic accuracy of ¹⁸F-FDG PET or PET/CT for the detection of VPGI. We calculated the pooled sensitivities and specificities of included studies, calculated positive and negative likelihood ratios, and obtained summary receiver operating characteristic curves.

RESULTS

Across 10 studies (286 patients), the pooled sensitivity was 0.96 (95% confidence interval [CI], 0.89-0.98) without heterogeneity (I² = 40.2; 95% CI, 0.0-84.4; P = .09), and pooled specificity was 0.74 (95% CI, 0.67-0.81) without heterogeneity (I² = 39.9; 95% CI, 0.0-84.3; P = .09). Likelihood ratio syntheses showed an overall positive likelihood ratio of 3.7 (95% CI, 2.9-4.9) and negative likelihood ratio of 0.06 (95% CI, 0.02-0.15). The pooled diagnostic odds ratio was 63 (95% CI, 23-173). The hierarchical summary receiver operating characteristic curve showed the area under the curve to be 0.87 (95% CI, 0.83-0.89).

CONCLUSIONS

This study showed the high sensitivity and moderate specificity of ¹⁸F-FDG PET or PET/CT for the detection of VPGI. The clinical usefulness of ¹⁸F-FDG PET or PET/CT for detection of VPGI should be validated through further large multicenter studies.

A meta-analysis of outcomes of in-situ reconstruction after total or partial removal of infected abdominal aortic graft

INTRODUCTION

There is currently a lack of evidence for the relative effectiveness of partial resection (PR) and total resection (TR) before managing abdominal aortic graft infection (AGI). Most authorities agree that TR is mandatory for intracavitary AGI in patients with favorable conditions but there is an increasing number of patients with severe comorbidities for whom this approach is not suitable, resulting in a prohibitive mortality rate. The purpose of this study was to determine the most appropriate indication for TR or PR.

EVIDENCE ACQUISITION

A meta-analysis was conducted on the rates of early/late mortality, amputations and reinfection. A meta-regression was performed with eight variables: patient age, male prevalence, presence of virulent or nonvirulent organisms, urgency, omentoplasty and follow-up.

EVIDENCE SYNTHESIS

Twenty-one studies and 1052 patients were included. For TR and PR, the rates of early mortality and reinfection were 16.8% and 10.5%, 11% and 27%, respectively. For TR urgency and male gender were associated with increased rate of early mortality and male gender, PDF and virulent organisms were associated with increased risk of reinfection. For PR no statistical correlation was analyzable except for PDF with increased risk of reinfection.

CONCLUSIONS

Early mortality rates are higher for TR and reinfection rates are higher for PR. For TR early mortality increases in urgent cases and it is suggested that alternative option must be discussed, reinfection decreases in the presence of nonvirulent organisms and TR seems optimal. For TR and PR reinfection increases in presence of PDF and alternative technique may be more appropriate.

Efficacy of Preoperative Antibiotic Therapy for the Treatment of Vascular Graft Infection

Objective: We aimed to assess the efficacy of preoperative antibiotic therapy for the treatment of prosthetic graft infection.

Materials and Methods: We retrospectively analyzed the treatment strategies used for managing patients with prosthetic vascular graft infections between 2000 and 2016. The patients were divided into two groups: early antibiotic (EA) group, those who were administered with antibiotics ≥2 weeks preoperatively and late antibiotic (LA) group, those who were administered with antibiotics <2 weeks preoperatively. We evaluated the outcomes including surgical procedures, length of hospital stay, and surgical revision.

Results: All the surgical procedures performed in the EA group were elective surgeries. Three of the 11 surgeries performed in the LA group were emergency surgeries (P=0.16). No significant differences were observed in the operative procedure (P=0.64), operation time (P=0.37), and blood loss (P=0.63) of the two groups. Although the length of postoperative hospital stay did not significantly differ (P=0.61), the total length of hospital stay was longer in the EA group (P=0.02). Surgical revisions were performed for five patients in the LA group and for none in the EA group (P=0.04).

Conclusion: Preoperative antibiotic therapy provided excellent outcomes in terms of avoiding surgical revisions in the treatment of vascular graft infection.

Daptomycin treatment in Gram-positive vascular graft infections

BACKGROUND

Daptomycin is a bactericidal antibiotic approved for the treatment of skin and soft tissue infections and right-side endocarditis. However, there is a lack of published data outlining its usefulness in vascular graft infections (VGI). The aim of this study was to describe the clinical experience of daptomycin use in the treatment of VGI caused by Gram-positive bacteria.

METHODS

This was a retrospective cohort study of patients diagnosed with VGI receiving daptomycin at a tertiary care hospital during the period January 2010 to December 2012.

RESULTS

Of a total 1066 consecutive patients who had undergone vascular grafts (VG), 25 were diagnosed with VGI. Fifteen of these patients (11 prosthetic VG, three autologous VG, one both types) received daptomycin (median dose 6.7mg/kg/day, range 4.1-7.1mg/kg/day; median age 69 years, range 45-83 years; 80% male). The infected bypass was removed in 13 cases. The most common reason for selecting daptomycin was kidney failure (53%). The Gram-positive organisms isolated were coagulase-negative Staphylococcus (n=10), Staphylococcus aureus (n=3) (two methicillin-resistant S. aureus), Enterococcus faecium (n=2), and Enterococcus faecalis (n=1). The mean follow-up was 69 months (interquartile range 48-72 months). Ten patients (66.7%) achieved complete healing of the VGI. A recurrence of the infection was observed in 100% of patients in whom the bypass was not removed. Among patients who did not achieve complete healing, one needed a supracondylar amputation and one died as a consequence of infection. Five patients received treatment with rifampicin in addition to daptomycin and they were all cured.

CONCLUSIONS

The use of daptomycin and surgery for Gram-positive VGI was effective and well tolerated, and this may be a good alternative for the treatment of VGI in patients with peripheral arterial disease in whom renal insufficiency is common.

Adherence of Staphylococcus aureus to Dyneema Purity® Patches and to Clinically Used Cardiovascular Prostheses

Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for prostheses is Dyneema Purity®, made of ultra-high-molecular-weight polyethylene. Dyneema Purity® fibers are very thin, flexible, resistant to fatigue and abrasion, and have high strength. S. aureus adherence to Dyneema Purity® was tested and compared with currently used cardiovascular prostheses. We compared adhesion of S. aureus to Dyneema Purity® (1 membrane-based and 1 yarn-composed patch) with 5 clinically used yarn-composed polyester and membrane-based expanded polytetrafluoroethylene patches. Patches were contaminated with S. aureus bacteria and bacterial adherence was quantified. S. aureus adherence was also visualized in flow conditions. Overall, bacterial adherence was higher on yarn-composed prosthesis materials, with a rough surface, than on the membrane-based materials, with a smooth surface. Adherence to Dyneema Purity® materials was non-inferior to the currently used materials. Therefore, patches of Dyneema Purity® might be attractive for use in cardiovascular applications such as catheter-based heart valves and endovascular prostheses by their good mechanical properties combined with their noninferiority regarding bacterial adhesion.

Diagnostic performance of 18F-FDG-PET/CT in vascular graft infections

OBJECTIVE

The aim of this study was to evaluate the diagnostic accuracy of positron emission tomography/computed tomography with (18)F-fludeoxyglucose (FDG-PET/CT) in a population with suspected graft infection and to validate a new diagnostic imaging score for FDG-PET/CT.

METHODS

This was a prospective cohort study. FDG-PET/CT was performed prospectively in 34 patients with suspected graft infection, in 12 of them before the start of antimicrobial treatment. Diagnostic accuracy was assessed using a new five point visual grading score and by using a binary score. Maximum standardized uptake values (SUVmax) were calculated for quantitative measurements of metabolic activity, and cut off points were calculated using the receiver operator curve (ROC). The standard of reference was a microbiological culture, obtained after open biopsy or graft explantation.

RESULTS

Using the new scale, FDG-PET/CT correctly recognized 27 patients with graft infection, one patient was diagnosed as false positive, six patients were correctly classified as true negative, and no patients were rated false negative. Hence, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG-PET/CT for the diagnosis of graft infections were 100%, 86%, 96%, 100%, and 97%, respectively. Using a previously established binary score, sensitivity, specificity, PPV, NPV, and accuracy were 96%, 86%, 96%, 86%, and 94% respectively. ROC analysis suggested an SUVmax cut off value of ≥3.8 to differentiate between infected and non-infected grafts (p < .001). Additionally, FDG-PET/CT provided a conclusive clinical diagnosis in six of seven patients without graft infection (i.e., other sites of infections).

CONCLUSIONS

The diagnostic accuracy of FDG-PET/CT in the detection of aortic graft infection is high. A newly introduced five point visual grading score and early imaging prior to antimicrobial treatment may further improve the diagnostic accuracy.

Multifunctional REDV-conjugated zwitterionic polycarboxybetaine–polycaprolactone hybrid surfaces for enhanced antibacterial activity, anti-thrombogenicity and endothelial cell proliferation

Multifunctional PCL hybrid surfaces are developed by grafting of REDV–zwitterionic polycarboxybetaine conjugates via surface-initiated ATRP.

Surgical and antimicrobial treatment of prosthetic vascular graft infections at different surgical sites: a retrospective study of treatment outcomes

Objective

Little is known about optimal management of prosthetic vascular graft infections, which are a rare but serious complication associated with graft implants. The goal of this study was to compare and characterize these infections with respect to the location of the graft and to identify factors associated with outcome.

Methods

This was a retrospective study over more than a decade at a tertiary care university hospital that has an established multidisciplinary approach to treating graft infections. Cases of possible prosthetic vascular graft infection were identified from the hospital's infectious diseases database and evaluated against strict diagnostic criteria. Patients were divided into groups according to the locations of their grafts: thoracic-aortic, abdominal-aortic, or peripheral-arterial. Statistical analyses included evaluation of patient and infection characteristics, time to treatment failure, and factors associated specifically with cure rates in aortic graft infections. The primary endpoint was cure at one year after diagnosis of the infection.

Results

Characterization of graft infections according to the graft location did show that these infections differ in terms of their characteristics and that the prognosis for treatment seems to be influenced by the location of the infection. Cure rate and all-cause mortality at one year were 87.5% and 12.5% in 24 patients with thoracic-aortic graft infections, 37.0% and 55.6% in 27 patients with abdominal-aortic graft infections, and 70.0% and 30.0% in 10 patients with peripheral-arterial graft infections. In uni- and multivariate analysis, the type of surgical intervention used in managing infections (graft retention versus graft replacement) did not affect primary outcome, whereas a rifampicin-based antimicrobial regimen was associated with a higher cure rate.

Conclusions

We recommend that future prospective studies differentiate prosthetic vascular graft infections according to the location of the grafts and that rifampicin-based antimicrobial regimens be evaluated in clinical trials involving vascular graft infections caused by staphylococci.

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Corynebacterium minutissimum vascular graft infection: case report and review of 281 cases of prosthetic device-related Corynebacterium infection

Corynebacterium spp. have proven their pathogenic potential in causing infections, particularly in the setting of immunosuppression and prosthetic devices. We conducted a PubMed literature review of all cases of Corynebacterium prosthetic device infections published in the English language through December 2013. The majority of cases involved peritoneal dialysis and central venous catheters, but prosthetic joints and central nervous system shunts/drains were also involved. The management of these cases in terms of retention or removal of the device was not uniform; however, the overall mortality remained the same among both groups. All of these prosthetic device infections pose potential problems in management when the device cannot be removed safely for the patient, especially with the lack of data on the pathogenicity of Corynebacterium species. However with better identification of species and sensitivities, successful treatment is possible even with retention of the device.

Factors predictive of treatment failure in staphylococcal prosthetic vascular graft infections: a prospective observational cohort study: impact of rifampin

BACKGROUND

There exists considerable debate concerning management of prosthetic vascular graft infection (PVGI), especially in terms of antimicrobial treatment. This report studies factors associated with treatment failure in a cohort of patients with staphylococcal PVGI, along with the impact of rifampin (RIF).

METHODS

All data on patients with PVGI between 2006 and 2010 were reviewed. Cure was defined as the absence of evidence of infection during the entire post-treatment follow-up for a minimum of one year. Failure was defined as any other outcome.

RESULTS

84 patients (72 M/12 F, median age 64.5 ± 11 y) with diabetes mellitus (n = 25), obesity (n = 48), coronary artery disease (n = 48), renal failure (n = 24) or COPD (n = 22) were treated for PVGI (median follow-up was 470 ± 469 d). PVGI was primarily intracavitary (n = 47). Staphylococcus aureus (n = 65; including 17 methicillin-resistant S. aureus) and coagulase-negative Staphylocococcus (n = 22) were identified. Surgical treatment was performed in 71 patients. In univariate analysis, significant risk factors associated with failure were renal failure (p = 0.04), aortic aneurysm (p = 0.03), fever (p = 0.009), aneurysm disruption (p = 0.02), septic shock in the peri-operative period (p = 0.005) and antibiotic treatment containing RIF (p = 0.03). In multivariate analysis, 2 variables were independently associated with failure:septic shock [OR 4.98: CI 95% 1.45-16.99; p=0.01] and antibiotic containing rifampin [OR: 0.32: CI95% 0.10-0.96; p=0.04].

CONCLUSION

Results of the present study suggest that fever, septic shock and non-use of antibiotic treatment containing RIF are associated with poor outcome.

Intra-abdominal aortic graft infection: prognostic factors associated with in-hospital mortality

BACKGROUND

Mortality associated with aortic graft infection is considerable. The gold standard for surgical treatment remains explantation of the graft. However, prognostic factors associated with early mortality due to this surgical procedure are not well-known.

METHODS

Retrospective analysis of patients admitted in our center between January 2006 and October 2011 for aortic graft infection. The primary endpoint was in-hospital mortality. A bivariate analysis of characteristics of patients associated with in-hospital outcome was performed.

RESULTS

Twenty five evaluable patients were studied. All patients were male. Their mean age was 67 ± 8.4 years. Most of them (92%) had severe underlying diseases. An in situ prosthetic graft replacement, mainly using cryopreserved arterial allografts, was performed in all patients, excepted one who underwent extra-anatomic bypass. Causative organisms were identified in 23 patients (92%). The in-hospital mortality rate was 48%. Among pre-operative characteristics, age ≥ 70 years, creatinine ≥ 12 mg/L and C reactive protein ≥ 50 mg/L were significantly associated with in-hospital mortality. Hospital mortality rates increased with the number of risk factor present on ICU admission, and were 0%, 14.3%, 85.7% and 100% for 0, 1, 2 and 3 factors, respectively. The only intra-operative factor associated with prognosis was an associated intestinal procedure due to aorto-enteric fistula. SAPS II, SOFA score and occurrence of medical or surgical complications were postoperative characteristics associated with in-hospital mortality.

CONCLUSION

Morbidity and mortality associated with surgical approach of aortic graft infections are considerable. Age and values of creatinine and C Reactive protein on hospital admission appear as the most important determinant of in hospital mortality. They could be taken into account for guiding the surgical strategy.

Clinical characteristics of infections in humans due to Staphylococcus epidermidis

Staphylococcus epidermidis is the most common cause of primary bacteremia and infections of indwelling medical devices. The ability to cause disease is linked to its natural niche on human skin and ability to attach and form biofilm on foreign bodies. This review focuses on the S. epidermidis clinical syndromes most commonly encountered by clinicians and future potential treatment modalities.

Infections of intravascular bare metal stents: a case report and review of literature

OBJECTIVE

The objective of the paper is to present a case of an infected bare metal stent in the left common iliac artery that was removed by an urgent operation, and to review the literature on diagnosis and outcome of infected coronary and non-coronary metal stents.

METHODS

A systematic search of the Medline database was performed with the purpose of identifying risk factors, signs and symptoms, imaging strategies, and treatment modalities of bare metal stent infections, both coronary and peripheral.

RESULTS

In total, 76 additional studies/case reports (48 non-coronary; 29 coronary) were included and analyzed. Intravascular bare metal stent infections are a rare but serious complication, often leading to emergency surgery (overall: 75.3%; non-coronary cases: 83.3%; coronary cases: 62.1%). In 25.0% of the non-coronary cases, infection led to amputation of an extremity or removal of viscera. Reported mortality was up to 32.5% of the cases (non-coronary: 22.9%; coronary 48.3%). Physicians should always be suspicious of a stent infection when patients present with aspecific symptoms such as fever and chills after stent placement. Additional imaging can be used to detect the presence of a pseudoaneurysm. A PET-CT is an ideal medium for identification of a stent infection.

CONCLUSIONS

Intravascular stent infection is associated with a high risk of morbidity and mortality. Surgery is the preferred treatment option, but not always possible, especially in patients with a coronary stent. In selected cases, bare metal stent infections may be prevented by the use of prophylactic antibiotics at stent placement.

Suppression of surgeons' bacterial hand flora during surgical procedures with a new antimicrobial surgical glove

BACKGROUND

Perforations of surgical gloves are common and increase with the duration of glove wear. Skin flora, re-grown after pre-operative disinfection of the hands, may contaminate a surgical site. An antimicrobial surgical glove with chlorhexidine on its inner surface has been developed. We hypothesized that by suppressing the re-growth of skin flora during the complete course of a surgical procedure, antimicrobial gloves may reduce the risk of surgical site contamination in the event of an intra-operative glove breach.

METHODS

We conducted a randomized, double-blind, single-center trial, to measure any differences in the bacterial skin populations of surgeons' hands during surgical procedures done with antimicrobial and non-antimicrobial surgical gloves [ISRCTN71391952]. In this study, 25 pairs of gloves were retrieved from 14 surgeons who donned them randomly on their dominant or non-dominant hand. The number of bacteria retrieved from glove fluid was measured and expressed as colony forming units (CFU)/mL.

RESULTS

The median cfu/mL of antimicrobial gloves was 0.00 (LQ: 0.00 CFU/mL; UQ: 0.00 cfu/mL), with a mean log10 cfu/mL=0.02 (range: 0.00-0.30). The median CFU/mL of non-antimicrobial gloves was 54.00 (LQ: 3.00 cfu/mL; UQ: 100.00 cfu/mL) with a mean log10 CFU/mL=1.32 (range: 0.00-2.39). After a mean operating time of 112 min, the difference in the log10 CFU/mL was 1.30 (p<0.001).

CONCLUSIONS

A new antimicrobial surgical glove suppressed surgeons' hand flora during operative procedures. In the event of a glove breach, the use of such a glove may have the potential to prevent bacterial contamination of a sterile surgical site, thereby decreasing the risk of surgical site infection (SSI) and increasing patient safety. Further clinical studies are needed to confirm this concept.

Successful management of postoperative necrotizing pancreatitis after infrarenal abdominal aortic aneurysm repair

We present a case of severe necrotizing pancreatitis that developed after elective repair of an abdominal aortic aneurysm. Surgeons are confronted in cases of postoperative acute pancreatitis with the dilemma of potential intraabdominal infection and the high risk of a subsequent infection of the retroperitoneal synthetic material. The therapeutic options range from a restrictive regime to radical necrosectomy and multivisceral resection.

Silver acetate coating promotes early vascularization of Dacron vascular grafts without inducing host tissue inflammation

BACKGROUND

Silver acetate is frequently used as an antimicrobial coating of prosthetic vascular grafts. However, the effects of this coating on the early inflammatory and angiogenic host tissue response still remain elusive. Therefore, the aim of the present in vivo study was to analyze the biocompatibility and vascularization of silver acetate-coated and uncoated vascular grafts during the initial phase after implantation.

METHODS

Two different prosthetic vascular grafts (ie, uncoated Dacron and silver acetate-coated Dacron Silver) were implanted into the dorsal skinfold chamber of C57BL/6 mice (n = 8 per group) to study angiogenesis and leukocytic inflammation at the implantation site by means of repetitive intravital fluorescence microscopy over a 14-day period. At the end of the in vivo experiments, collagen formation, apoptosis, and cell proliferation were analyzed in the newly developed granulation tissue surrounding the implants by histology and immunohistochemistry.

RESULTS

During the initial 14 days after implantation, Dacron Silver exhibited an improved vascularization, as indicated by a significantly increased functional capillary density compared with Dacron. This was not associated with a stronger leukocytic inflammatory host tissue response to the implants. Moreover, silver acetate coating did not affect collagen formation, apoptosis, and cell proliferation at the implantation site.

CONCLUSIONS

Silver acetate coating of prosthetic vascular grafts improves their early vascularization without inducing severe inflammatory side effects. Accordingly, this material modification crucially contributes to an improved incorporation of the implants into the host tissue, which may decrease the risk of vascular graft infection.