Long-term outcomes of lower extremity graft preservation using antibiotic beads in patients with early deep wound infections after major arterial reconstructions

Fostering Collaborative Teamwork-A Comprehensive Approach to Vascular Graft Infection Following Arterial Reconstructive Surgery

Vascular graft infection (VGI) is one of the most serious complications following arterial reconstructive surgery. VGI has received increasing attention over the past decade, but many questions remain regarding its diagnosis and management. In this review, we describe our approach to VGI through multidisciplinary collaboration and discuss decision making for challenging presentations. This review will concentrate on VGI that impacts both aneurysms and pseudoaneurysms excluding the ascending thoracic aorta.

Biological mechanisms of infection resistance in tissue engineered blood vessels compared to synthetic expanded polytetrafluoroethylene grafts

Objective

Synthetic expanded polytetrafluoroethylene (ePTFE) grafts are known to be susceptible to bacterial infection. Results from preclinical and clinical studies of bioengineered human acellular vessels (HAVs) have shown relatively low rates of infection. This study evaluates the interactions of human neutrophils and bacteria with ePTFE and HAV vascular conduits to determine whether there is a correlation between neutrophil-conduit interactions and observed differences of their infectivity in vivo.

Methods

A phase III comparative clinical study between investigational HAVs (n = 177) and commercial ePTFE grafts (n = 178) used for hemodialysis access (ClinicalTrials.gov Identifier: NCT02644941) was evaluated for conduit infection rates followed by histological analyses of HAV and ePTFE tissue explants. The clinical histopathology of HAV and ePTFE conduits reported to be infected was compared with immunohistochemistry of explanted materials from a preclinical model of bacterial contamination. Mechanistic in vitro studies were then conducted using isolated human neutrophils seeded directly onto HAV and ePTFE materials to analyze neutrophil viability, morphology, and function.

Results

Clinical trial results showed that the HAV had a significantly lower (0.93%; P = .0413) infection rate than that of ePTFE (4.54%). Histological analysis of sections from infected grafts explanted approximately 1 year after implantation revealed gram-positive bacteria near cannulation sites. Immunohistochemistry of HAV and ePTFE implanted in a well-controlled rodent infection model suggested that the ePTFE matrix permitted bacterial infiltration and colonization but may be inaccessible to neutrophils. In the same model, the HAV showed host recellularization and lacked detectable bacteria at the 2-week explant. In vitro results demonstrated that the viability of human neutrophils decreased significantly upon exposure to ePTFE, which was associated with neutrophil elastase release in the absence of bacteria. In contrast, neutrophils exposed to the HAV material retained high viability and native morphology. Cocultures of neutrophils and Staphylococcus aureus on the conduit materials demonstrated that neutrophils were more effective at ensnaring and degrading bacteria on the HAV than on ePTFE.

Conclusions

The HAV material seems to demonstrate a resistance to bacterial infection. This infection resistance is likely due to the HAV's native-like material composition, which may be more biocompatible with host neutrophils than synthetic vascular graft material.

Implementation of an antimicrobial stewardship program in the Vascular Surgery ward of a university tertiary care hospital in Pavia, Northern Italy

PURPOSE

The commitment of multidisciplinary teams in antimicrobial stewardship programs (ASPs) is often inadequately considered, especially in surgical wards. We wanted to evaluate clinical, microbiological, and pharmacological outcomes before and after the implementation of an ASP in the Vascular Surgery ward of Fondazione IRCCS Policlinico San Matteo, a tertiary care hospital in Pavia, Italy.

METHODS

This was a quasi-experimental quality-improvement study. The antimicrobial stewardship activity was conducted twice a week for 12 months and consisted of both prospective audit and feedback of all the ongoing antimicrobial prescriptions by the infectious diseases' consultants and educational meetings for the healthcare workers of the Vascular Surgery ward. For comparison between the study periods, Student t test (Mann-Whitney test for skewed distributions) was used for quantitative variables (ANOVA or Kruskall-Wallis for > 2 groups respectively), and Pearson's chi-squared test (Fisher exact test where appropriate) for categorical variables. 2-tailed tests were used. P-value significance cut-off was 0.05.

RESULTS

During the 12-month intervention period, among a total number of 698 patients, 186 prescriptions were revised, mostly leading to de-escalating an ongoing antimicrobial therapy (39, 20.97%). A statistically significant reduction in isolates of carbapenem-resistant Pseudomonas aeruginosa (p-value 0.003) and the absence of Clostridioides difficile infections were reported. No statistically significant changes were observed in terms of length of stay and all-cause in-hospital mortality. A significant decrease in the administration of carbapenems (p-value 0.01), daptomycin (p-value < 0.01) and linezolid (p-value 0.43) was registered. A significant reduction in antimicrobial costs was also observed.

CONCLUSIONS

The implementation of a 12-month ASP brought significant clinical and economic results, highlighting the benefits of a multidisciplinary teamwork.

Extra-anatomic Bypass and Excision is Superior to Graft Salvage Attempts with Antibiotic Beads to Treat Vascular Graft Infections in the Groin

OBJECTIVES

To determine if conventional extra-anatomic bypass and graft removal vs aggressive attempts at graft preservation has better survival and limb salvage in patients with localized groin wound infections of vascular grafts.

METHODS

We conducted a retrospective review of 53 consecutive patients with vascular graft infections presenting in the groin. Treatment groups consisted of group 1) extra-anatomic bypass and graft excision (N=22) and group 2) initial graft preservation attempts with utilization of antibiotic beads (N=31). In group 2, patients underwent serial debridement and placement of antibiotic beads until culture negative wounds were achieved. Significantly more patients underwent muscle flap coverage in group 2 (27 of 31) compared to group 1 (7 of 22) (p<0.001). Data collected included demographics, comorbidities, intraoperative details, and outcomes including patency, limb salvage, mortality, and number of procedures. Continuous variables were examined with Student's t-test and dichotomous variables were examined with Chi-Squared. Linear and logistic regression were used to analyze factors associated with outcomes, and Kaplan-Meier with log rank.

RESULTS

Both groups were similar with respect to demographics. The overall Kaplan-Meier 1- and 3-year survival rates were 66.2% and 34.1% with no statistically significant difference between groups. The Kaplan-Meier 1- and 3-year limb salvage rates were 68.8% and 36.6% for group 1 vs 58.5% and 38.7% for group 2 (p=NS). The 1- and 3-year primary patency rates were 71% and 71% in traditional group 1 vs 72% and 56% in group 2 (p=NS). 1- and 3-year secondary patency rates in traditional group 1 were 83% and 71% vs 85% and 61% in group 2 (p=NS). Patients in group 1 underwent fewer total procedures when compared to group 2 (2.3+.2 vs 5.1 +.7, p=0.03). The late reinfection rate was significantly less in group 1- 4.5% vs group 2- 26% (p=0.04). Freedom from reinfection at 1- and 3-years was 94% and 94% in traditional group 1 vs 74% and 62% in group 2 (p=0.03). Multivariable analysis showed a higher incidence of amputation in patients who suffered reinfection (N=13, p=0.049). There was a higher mortality in patients with septic shock (N=10, p=0.007) and reinfection (N=13, p=0.036). Reinfection was associated with the highest mortality (p=0.03).

CONCLUSIONS

Conventional graft excision with extra-anatomic bypass resulted in similar mortality when compared to aggressive attempts at graft preservation, and trended towards improved limb salvage and patency. However, attempts at graft preservation with antibiotic beads resulted in a significantly higher reinfection rate and greater number of procedures, and therefore this approach should be used very selectively.

Long-term prognosis following vascular graft infection: a 10-year cohort study

Background

Vascular graft infection (VGI) remains a severe disease with high mortality and relapse rates. We performed a retrospective single-center cohort study to highlight factors associated with long-term all-cause mortality in patients with vascular graft infection.

Methods

All patients hospitalized in our facility over 10 years for VGI were included. VGI was defined by the presence of a vascular graft or an aortic stent graft (stent or fabric), associated with 2 criteria among clinical, biological, imaging, or microbiological elements in favor of VGI. The primary outcome was all-cause mortality. Empirical antibiotic therapy was considered as appropriate when all involved pathogens were susceptible in vitro to the antibiotics used. The surgical strategy was defined as nonoptimal when the graft was not removed in a late-onset surgery (>3 months) or no surgery was performed.

Results

One hundred forty-six patients were included. Empirical antibiotic therapy was administered in 98 (67%) patients and considered appropriate in 55 (56%) patients. Surgery was performed in 136 patients (96%) and considered as optimal in 106 (73%) patients. In multivariable analysis, appropriate empirical antibiotic therapy was associated with a lower probability of mortality (hazard ratio, 0.47 [95% confidence interval, .30–.79]; P = .002). Long-term survival did not differ according to whether the surgical strategy was considered optimal or not (log-rank = 0.66).

Conclusions

Appropriate empirical antibiotic therapy is a cornerstone of the management of VGI. Whenever possible, antibiotics must be associated with optimal surgical management. However, surgery could potentially be avoided in comorbid patients who are treated with appropriate antibiotics.

Treatment of Early Deep Wound Infections after Arterial Reconstructions: A Meta-Analysis and Survey

BACKGROUND

Peripheral vascular graft infections, a serious concern after open lower extremity interventions, are treated using multiple strategies. Yet, there is no consensus on the optimal treatment. This study summarizes the literature and compares aggregate effect sizes between graft preservation with antibiotic beads and total graft excision.

METHODS

Manuscripts published between 1972 and 2019 were systematically queried using Ovid Medline and PubMed. Studies were included if they described early (≤4 months of the index procedure) infection-related outcomes after extracavitary and infrainguinal arterial graft infections that were managed with antibiotic-loaded beads or total excisions. Outcomes assessed included the prevalence of graft preservation failure, reinfection, and major amputation. To examine current preferences on this subject, a voluntary, anonymous survey was administered to practicing members of the Society for Clinical Vascular Surgery.

RESULTS

Six graft preservation studies (n = 147 patients) were included in the meta-analysis, based on PRISMA guidelines. The meta-analytic pooled proportion of patients with: (1) graft preservation failure was 0.09 (95% CI: 0.00, 0.46, I² = 88.8%), (2) reinfection was 0.04 (95% CI: 0.00, 0.18, I² = 79.7%), and (3) major amputation was 0.00 (95% CI: 0.00, 0.04, I² = 0%). Five studies addressing total excisions were identified via the systematic review however, their combined sample size (n = 28 patients) impeded use of a meta-analysis. Ninety (19%) licensed surgeons participated in the survey. In a hemodynamically stable, nonseptic patient, 67% (60) of respondents routinely excise the graft, while 31% (28) prefer preservation.

CONCLUSIONS

Study design and patient characteristic-related heterogeneity limited our ability to generate robust, clinical evidence-level outcome estimates. A prospective study is necessary to definitively establish the efficacy of antibiotic beads in the treatment and preservation of vascular graft infections.