The Microbiology of Infective Native Aortic Aneurysms in a Population-Based Setting

Danish Nationwide Study on Surgical Treatment of Infective Native Abdominal Aortic Aneurysms

OBJECTIVE

This study aimed to describe surgical trends, survival, and infection related complications (IRC) in a Danish cohort of patients with infective native aortic aneurysms (INAAs).

METHODS

A retrospective nationwide cohort study including all patients in Denmark who were surgically treated for abdominal INAA between 2000 and 2020 was conducted. Patients were identified through the Danish vascular registry, Karbase, which is a database registering all patients treated with vascular surgery in Denmark. Subsequent data on clinical presentation, treatment, all cause mortality, and complications were obtained from the electronic patient charts.

RESULTS

Seventy-five patients were included in the study, of whom 60 (80%) were male, with a median age of 69 (IQR 64, 75) years. Open surgical repair (OSR) was performed in 54 (72%) patients and endovascular aortic repair (EVAR) in 21 (28%). Median follow up was 52 (IQR 32, 103) months. Open repair was consistently the most frequent treatment modality throughout the study period, but EVAR became more frequent over time. The 30 day survival of the total cohort was 97% (94 - 100%). Kaplan-Meier survival estimates for the cohort were 92% (95% CI 85 - 98%), 80% (95% CI 71 - 91%), 63% (95% CI 52 - 78%), and 48% (95% CI 35 - 66%) at one, three, five and 10 years, respectively. Patients treated by EVAR had comparable long term survival to patients treated by OSR, with a hazard ratio of 0.35 (95% CI 0.10 - 1.22), but was associated with better short term survival up to five years. The most common cause of death was sepsis. Five (9%) OSR patients had IRC compared with one (5%) EVAR patient.

CONCLUSION

In this nationwide study of patients treated for abdominal INAA, an increasing number of patients were surgically treated during the study period. Patients treated by EVAR demonstrated long term survival comparable to OSR. The incidence of post-operative IRC was low. These results should be interpreted with caution and prospective registries are needed.

Infective Native Aortic Aneurysm: a Delphi Consensus Document on Treatment, Follow Up, and Definition of Cure

OBJECTIVE

Evidence is lacking to guide the management of infective native aortic aneurysm (INAA). The aim of this study was to establish expert consensus on surgical and antimicrobial treatment and follow up, and to define when an INAA is considered cured.

METHODS

Delphi methodology was used. The principal investigators invited 47 international experts (specialists in infectious diseases, radiology, nuclear medicine, and vascular and cardiothoracic surgery) via email. Four Delphi rounds were performed, three weeks each, using an online questionnaire with initially 28 statements. The panellists rated the statements on a five point Likert scale. Comments on statements were analysed, statements were revised and added or deleted, and the results were presented in the iterative rounds. Consensus was defined as ≥ 75% of the panel rating a statement as strongly agree or agree on the Likert scale, and consensus on the final assessment was defined as Cronbach's alpha > 0.80.

RESULTS

All 49 panellists completed all four rounds, resulting in 100% participation. One statement was added based on the results and comments of the panel, resulting in 29 final statements: three on need for consensus, 20 on treatment, five on follow up, and one on definition of cure. All 29 statements reached agreement of ≥ 86%. Cronbach's alpha increased for each consecutive round; round 1, 0.85; round 2, 0.90; round 3, 0.91; and round 4, 0.94. Thus, consensus was reached for all statements.

CONCLUSION

INAAs are rare, and high level evidence to guide optimal management is lacking. This consensus document was established with the aim of helping clinicians manage these challenging patients, as a supplement to current guidelines. The presented consensus will need future amendments in accordance with newly acquired knowledge.

Outcomes of Endovascular Treatment for Infective Aortic Aneurysms - A Multicenter Retrospective Study

BACKGROUND

In Taiwan, infective native aortic aneurysms (INAAs) are relatively common, so the aim of present study was to demonstrate the comparative outcomes of endovascular repair for thoracic and abdominal INAAs.Methods and Results: Patients with naïve thoracic or abdominal INAAs managed with endovascular repair between 2001 and 2018 were included in this multicenter retrospective cohort. The confounding factors were adjusted with propensity score (PS). Of the 39 thoracic and 43 abdominal INAA cases, 41 (50%) presented with aneurysmal rupture, most of which were at the infrarenal abdominal (n=35, 42.7%) or descending thoracic aorta (n=25, 30.5%). Salmonella spp. was the most frequently isolated pathogen. The overall in-hospital mortality rate was 18.3%. The risks of in-hospital death and death due to rupture were significantly lower with thoracic INAAs (12.8% vs. 23.3%; PS-adjusted odds ratio (OR) 0.24, 95% confidence interval (CI) 0.06-0.96; 0.1% vs. 9.3%; PS-adjusted OR 0.11, 95% CI 0.01-0.90). During a mean follow-up of 2.5 years, the risk of all-cause death was significantly higher with thoracic INAAs (35.3% vs. 15.2%; PS-adjusted HR 6.90, 95% CI 1.69-28.19). Chronic kidney disease (CKD) was associated with death.

CONCLUSIONS

Compared with thoracic INAAs, endovascular repair of abdominal INAAs was associated with a significantly higher in-hospital mortality rate. However, long-term outcomes were worse for thoracic INAAs, with CKD and infections being the most important predictor and cause of death, respectively.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Ruptured Mycotic Thoracic Aortic Aneurysm in the Setting of Streptococcus Bacteremia with Underlying Colonic Malignancy

Ruptured mycotic thoracic aortic aneurysms (TAAs) pose complex clinical challenges which are often compounded by existing comorbidities of the typical patient. We present the case of an 85-year-old female presenting emergently with a ruptured mycotic TAA with underlying Streptococcus bacteremia who was successfully treated with a thoracic endograft and antibiotics.

Biofilm formation on endovascular aneurysm repair (EVAR) grafts-a proof of concept in vitro model

OBJECTIVES

An endovascular aneurysm repair (EVAR) graft is a catheter-implanted vascular prosthesis and is the preferred treatment for patients with aortic aneurysm. If an EVAR graft becomes the focus of infection, the treatment possibilities are limited because it is technically difficult to remove the graft to obtain source control. This study examines whether Pseudomonas aeruginosa and Staphylococcus aureus form biofilm on EVAR prostheses.

METHODS

EVAR graft sections were exposed to bacteria at 102 or 108 colony forming units (CFU)/mL in lysogeny broth and Krebs-Ringer at 37°C, bacterial biofilm formation was evaluated by scanning electron microscopy and counting CFU on the graft sections after antibiotic exposure at × 10 minimal inhibitory concentration. Bacteria were tested for tolerance to benzylpenicillin, tobramycin, and ciprofloxacin.

RESULTS

Bacterial exposure for 15 minutes established biofilms on all prosthesis fragments (6/6 replicates). After 4 hours, bacteria were firmly attached to the EVAR prostheses and resisted washing. After 18-24 hours, the median CFU/g of EVAR graft reached 5.2 × 108 (1.15 × 108-1.1 × 109) for S. aureus and 9.1 × 107 (3.5 × 107-6.25 × 108) for P. aeruginosa. Scanning electron microscopy showed bacterial attachment to the graft pieces. There was a time-dependent development of tolerance with approximately 20 (tobramycin), 560 (benzylpenicillin), and 600 (ciprofloxacin) times more S. aureus surviving antibiotic exposure in 24- compared with 0-hour-old biofilm. Five (tobramycin) and 170 times (ciprofloxacin) more P. aeruginosa survived antibiotic exposure in 24- compared with 0-hour-old biofilms.

DISCUSSION

Our results show that bacteria can rapidly adhere to and subsequently form antibiotic-tolerant biofilms on EVAR graft material in concentrations equivalent to levels seen in transient bacteraemia in vivo. Potentially, the system can be used for identifying optimal treatment combinations for infected EVAR prosthesis.

An autopsy case of infective aortic aneurysm with Pasteurella multocida infection: clinicopathological appearance and a review of literatures

Here, we showed our clinicopathological findings of infected aortic aneurysm (IAA) with Pasteurella multocida, which is a Gram-negative coccobacillus and is part of the normal oral flora of many animals. The patient was a 76-year-old male animal owner with a history of diabetes mellitus, alcoholic liver damage, and laryngeal cancer. He died 16 days after admission without undergoing operation because of poor general condition. Autopsy showed saccular outpouching with loss of the existing aortic wall and marked neutrophilic infiltration in the suprarenal abdominal aorta. Rupture was not evident. A polymerase chain reaction assay using DNA extracted from formalin-fixed paraffin-embedded specimen of the aneurysmal wall detected the Pasteurella multocida gene, therefore we conclude that the present case was IAA of native aorta with Pasteurella multocida infection. A review of the literature showed that IAA of native aorta with Pasteurella multocida infection is opportunistic and that liver disorder, alcohol addiction, diabetes mellitus, and animal bite may increase its risk. On the other hand, aortic endograft infection with Pasteurella multocida frequently occurred without an immunocompromised state. Pasteurella multocida may be a distinct causative microorganism in IAA, and/or sepsis when the participant is an animal owner.

Infective Native Extracranial Carotid Artery Aneurysms: A Systematic Review

BACKGROUND

Infective native extracranial carotid artery aneurysms are rare, and their management is variable due to a lack of evidence assessing outcomes.

METHODS

We performed a systematic literature review following PRISMA guidelines to identify all reported cases of infective native extracranial carotid artery aneurysms between January 1970 and March 2021.

RESULTS

This study identified 193 infective native aneurysms of the extracranial carotid artery from 154 sources. Patients were predominantly male (71.4%), and age ranged from 6 months to 89 years old. The most common presenting features were a neck mass and fever, but also included hemorrhage, respiratory distress, and neurological symptoms. Most aneurysms were located in the internal carotid artery (47.4%). Staphylococcus (23.3%) was the most commonly identified causative pathogen, followed by Mycobacterium tuberculosis (20.9%). Most appeared to become infected by direct local spread. Treatment strategies involved open surgical methods in 101 cases and an endovascular approach in 41 cases. In 4 cases, a hybrid method involving concurrent endovascular and open surgical management was undertaken. In 5 cases, there was antibiotic treatment alone. In the open surgery-treated group, the complication rate was 20.8% compared to 13.2% in the endovascular group. Mortality rate was 5.6%.

CONCLUSIONS

Our review identified 193 cases of infective native extracranial carotid artery aneurysms. Direct local spread of a staphylococcus infection was the commonest cause. Endovascular management was associated with fewer early complications than open surgical management.

Predicting Infection Related Complications After Endovascular Repair of Infective Native Aortic Aneurysms

OBJECTIVE

Endovascular aortic repair (EVAR) as surgical treatment for infective native aortic aneurysm (INAA) is associated with superior survival compared with open surgery, but with the risk of infection related complications (IRCs). This study aimed to assess the association between baseline clinical and computed tomography (CT) features and the risk of post-operative IRCs in patients treated with EVAR for INAA. It also sought to develop a model to predict long term IRCs in patients with abdominal INAA treated with EVAR.

METHODS

All initial clinical details and CT examinations of INAAs between 2005 and 2020 at a major referral hospital were reviewed retrospectively. The images were scrutinised according to aneurysm features, as well as peri-aortic and surrounding organ involvement. Data on post-operative IRCs were found in the patient records. Cox regression analysis was used to derive predictors for IRCs and develop a model to predict five year IRCs after EVAR in abdominal INAA.

RESULTS

Of 3 780 patients with the diagnosis of aortic aneurysm or aortitis, 98 (3%) patients were treated with EVAR for abdominal INAAs and were thus included. The mean follow up time was 52 months (range 0 ‒ 163). The mean transaxial diameter was 6.5 ± 2.4 cm (range 2.1 ‒14.7). In the enrolled patients, 38 (39%) presented with rupture. The five year IRC rate in abdominal INAAs was 26%. Female sex, renal insufficiency, positive blood culture, aneurysm diameter, and psoas muscle involvement were predictive of five year IRC in abdominal INAA after EVAR. The model had a C-index of 0.76 (95% CI 0.66 - 0.87).

CONCLUSION

Pre-operative clinical and CT features have the potential to predict IRC after endovascular aortic repair in INAA patients. These findings stress the importance of rigorous clinical, laboratory, and radiological follow up in these patients.

Retrospective Multicenter Study Comparing Infectious and Noninfectious Aortitis

BACKGROUND

Determining the etiology of aortitis is often challenging, in particular to distinguish infectious aortitis (IA) and noninfectious aortitis (NIA). This study aims to describe and compare the clinical, biological, and radiological characteristics of IA and NIA and their outcomes.

METHODS

A multicenter retrospective study was performed in 10 French centers, including patients with aortitis between 1 January 2014 and 31 December 2019.

RESULTS

One hundred eighty-three patients were included. Of these, 66 had IA (36.1%); the causative organism was Enterobacterales and streptococci in 18.2% each, Staphylococcus aureus in 13.6%, and Coxiella burnetii in 10.6%. NIA was diagnosed in 117 patients (63.9%), mainly due to vasculitides (49.6%), followed by idiopathic aortitis (39.3%). IA was more frequently associated with aortic aneurysms compared with NIA (78.8% vs 17.6%, P < .001), especially located in the abdominal aorta (69.7% vs 23.1%, P < .001). Crude and adjusted survival were significantly lower in IA compared to NIA (P < .001 and P = .006, respectively). In the IA cohort, high American Society of Anesthesiologists score (hazard ratio [HR], 2.47 [95% confidence interval {CI}, 1.08-5.66]; P = .033) and free aneurysm rupture (HR, 9.54 [95% CI, 1.04-87.11]; P = .046) were significantly associated with mortality after adjusting for age, sex, and Charlson comorbidity score. Effective empiric antimicrobial therapy, initiated before any microbial documentation, was associated with a decreased mortality (HR, 0.23, 95% CI, .08-.71]; P = .01).

CONCLUSIONS

IA was complicated by significantly higher mortality rates compared with NIA. An appropriate initial antibiotic therapy appeared as a protective factor in IA.

Mycotic Thoracic Aortic Aneurysm: Epidemiology, Pathophysiology, Diagnosis, and Management

Mycotic thoracic aortic aneurysm (MTAA) is an aneurysm of the aorta caused by infection of the vessel tissue through microbial inoculation of the diseased aortic endothelium. It is most commonly caused by bacteria. Rarely, it can be caused by fungi. However, viral aortic aneurysm has never been reported. Depending on the area and time period investigated, the infections organism discovered may vary significantly. Little is known about the natural history of MTAA due to its rarity. It is not known if they follow the same pattern as other TAAs. However, it is unclear whether MTAA follows a similar clinical course. The combination of clinical presentation, laboratory results, and radiographic results are used to make the diagnosis of MTAA. Treatment of MTAA is complex since patients frequently present at a late stage, frequently with fulminant sepsis, as well as concomitant complications such as aneurysm rupture. While medical treatment, including antibiotics, is recommended, surgery is still the mainstay of management. Surgery to treat MTAA is complicated and carries a high risk of morbidity and mortality and includes both open repairs and endovascular ones. In this review, we explore the etiology, pathogenesis, clinical presentations, diagnostic modalities as well as treatment management available for MTAA.