An unusual case of Cardiobacterium valvarum causing aortic endograft infection and osteomyelitis.

BACKGROUND: HACEK (Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella corrodens, and Kingella spp.) group organisms are responsible for 0.8% to 6% of all infective endocarditis cases, with Cardiobacterium spp. being the third most commonly implicated HACEK microorganism. Within this genus is Cardiobacterium valvarum (C. valvarum), a novel organism described in 2004. To date, only 15 cases of C. valvarum infection have been reported in the English-language literature, and have primarily been cases of infective endocarditis in patients with valvular disease. C. valvarum has not been reported to cause infections spreading to the surrounding bone. CASE PRESENTATION: We present a case of a 57-year-old man with a history of aortic dissection followed by aortic endograft replacement who presented with back pain. He was found to have radiographic evidence of an infected aortic endograft, along with vertebral osteomyelitis, discitis, and epidural phlegmon. Blood cultures identified C. valvarum as the causative organism. The patient was treated with ceftriaxone and surgical intervention was deferred due to the patient's complex anatomy. His course was complicated by septic cerebral emboli resulting in cerebrovascular accident. CONCLUSIONS: This case report highlights C. valvarum, a rare and emerging HACEK group microorganism that warrants consideration in high-risk patients with evidence of subacute infection and disseminated disease. While C. valvarum classically presents as infective endocarditis, extra-cardiac manifestations have also been described. As demonstrated in this case, endograft involvement and osteomyelitis may occur in rare circumstances.

Results of cryopreserved arterial allograft replacement for thoracic and thoracoabdominal aortic infections.

BACKGROUND: Primary and secondary thoracic aortic infections are rare but associated with high morbidity and mortality. There is currently no consensus on their optimal treatment. Arterial allografts have been shown to be resistant to bacterial colonization. Complete excision of infected material, especially synthetic grafts, combined with in situ aortic repair is considered the best treatment of abdominal aortic infections. The aim of this study was to assess the management of thoracic and thoracoabdominal aortic infections using arterial allografts. METHODS: Between January 2009 and December 2017, all patients with thoracic and thoracoabdominal aortic native or graft infections underwent complete excision of infected material and in situ arterial allografting. The end points were the early mortality and morbidity rates and early and late rates of reinfection, graft degeneration, and graft-related morbidity. RESULTS: Thirty-five patients with a mean age of 65.6 ± 9.2 years were included. Twenty-one (60%) cases experienced graft infections and 14 (40%) experienced native aortic infections. Eight (22.8%) patients had visceral fistulas: 5 (14.4%) prosthetic-esophageal, 1 (2.8%) prosthetic-bronchial, 1 (2.8%) prosthetic-duodenal, and 1 (2.8%) native aortobronchial. In 12 (34.3%) cases, only the descending thoracic aorta was involved; in 23 (65.7%) cases, the thoracoabdominal aorta was involved. Fifteen (42.8%) patients died during the first month or before discharge: 5 of hemorrhage, 4 of multiorgan failure, 3 of ischemic colitis, 2 of pneumonia, and 1 of anastomotic disruption. Eleven (31.5%) patients required early revision surgery: 6 (17.1%) for nongraft-related hemorrhage, 3 (8.6%) for colectomy, 1 (2.9%) for proximal anastomotic disruption, and 1 (2.9%) for tamponade. One (2.9%) patient who died before discharge experienced paraplegia. One (2.9%) patient experienced stroke. Six (17.1%) patients required postoperative dialysis. Among them, four died before discharge. The mean length of stay in the intensive care unit was 11 ± 10.5 days; the mean length of hospital stay was 32 ± 14 days. During a mean follow-up of 32.3 ± 23.7 months, three allograft-related complications occurred in survivors (15% of late survivors): one proximal and one distal false aneurysm with no evidence of reinfection and one allograft-enteric fistula. The 1-year and 2-year survival rates were 49.3% and 42.5%, respectively. CONCLUSIONS: Although rare, aortic infections are highly challenging. Surgical management includes complete excision of infected tissues or grafts. Allografts offer a promising solution to aortic graft infection because they appear to resist reinfection; however, the grafts must be observed indefinitely because of the risk of late graft complications.

Sildenafil citrate long-term treatment effects on cardiovascular reactivity in a SHR experimental model of metabolic syndrome.

Much evidence indicates that metabolic syndrome is strongly correlated with a decrease in nitric oxide and an increase in oxidative stress leading to cardiovascular alterations. In recent years, gut microbiota has emerged as a new contributor to the metabolic syndrome establishment and associated cardiovascular diseases, but the underlying mechanisms remain unclear. We hypothesized that a positive modulation of cyclic guanosine monophosphate (cGMP) pathway, through phosphodiesterase type 5 (PDE5) inhibition could prevent cardiovascular alterations and gut dysbiosis that may be associated to metabolic syndrome. Spontaneously hypertensive rats (SHR) were randomly divided into 4 groups: control, cafeteria diet (CD) and sildenafil citrate treated groups (5mg/kg per os) were given either a CD or a standard chow diet for 10 weeks. Body weight, arterial blood pressure and glucose tolerance test were monitored. At the 10th week, cardiac inotropy and coronary perfusion pressure were evaluated on isolated heart according to Langendorff method. Cumulative concentration response curves to phenylephrine and acetylcholine were determined on thoracic aorta rings for vascular reactivity evaluation. Faecal samples were collected for the gut microbiota analysis. Compared to the control group, CD-fed rats showed a significant increase in body weight gain, arterial blood pressure and were glucose intolerant. This group showed also a decrease in ß-adrenoceptor-induced cardiac inotropy and coronary vasodilation. Gut microbiota analysis revealed a significant reduction in the abundance of Lactobocillus spp in cafeteria diet-fed rats when compared to the control ones. Sildenafil citrate long-term treatment decreased weight gain and arterial blood pressure, improved coronary vasodilation and reduced α1-adrenoceptor-induced vasoconstriction in CD group. However, it did not reverse gut dysbiosis induced by chronic CD feeding. These results suggest that cGMP pathway targeting may be a potential therapeutic strategy for the management of the metabolic syndrome and associated cardiovascular disorders.

Infected aneurysm of the thoracic aorta probably caused by Bacillus cereus: a case report.

BACKGROUND: An infected aneurysm of the thoracic aorta is a rare clinical condition with significant morbidity and mortality. Patients with fast-growing aortic aneurysms show a high incidence of rupture. Gram-positive organisms, such as the Staphylococcus and Enterococcus species, are the most common cause of infection. CASE PRESENTATION: A 91-year-old man presented at our facility with high grade fever and tachypnea, which he had experienced for the previous two days. He had a history of end-stage renal disease and had been undergoing regular chest computed tomography (CT) follow-up for a left lower lung nodule. CT imaging with intravenous contrast media showed a thoracic aortic aneurysm with hemothorax. Rupture of the aneurysm was suspected. CT imaging performed a year ago showed a normal aorta. Blood samples showed a Bacillus cereus infection. The patient was successfully treated for a mycotic aortic aneurysm secondary to Bacillus cereus bacteremia. CONCLUSIONS: Here, we report a rare of an infected aneurysm of the thoracic aorta probably caused by Bacillus cereus. Although infected aneurysms have been described well before, an aneurysm infected with Bacillus cereus is rare. Bacillus cereus, a gram-positive spore-building bacterium, can produce biofilms, which attach to catheters. It has recently emerged as a new organism that can cause serious infection.

Opinion: Aortic Graft Infection-Any Guidelines or Just Surgeon's Experience Lines!

Aggressive strategies for thoracic aortic graft infection, including resection of all infected tissues, in situ replacement with a rifampicin-bonded graft, and omental flap installation, resulted in improved survival.

Glomerulonephritis triggered by chronical aortic graft infection in a male with Loeys-Dietz syndrome: A case report.

RATIONALE: Glomerulonephritis triggered by a chronically infected graft is increasingly identified because of widely used implanted device. Removal of the aortic graft and sustained antibiotic therapy is the usual approach to maximize the chance of renal recovery, but as this case shows graft removal is not always possible. PATIENT CONCERNS: A 35-year-old man with intractable and recurrent fever had acute renal failure in sustained antibiotic therapy. DIAGNOSES: Renal biopsy suggested crescentic glomerulonephritis. fluorodeoxyglucose/positron emission tomography-computed tomography showed increased metabolic activity at the site of aortic graft, reminding that chronic infection of an implanted graft can lead to severe glomerulonephritis. TGFBR2 c.1133G>T mutation was observed in mutation analysis, which was reported to be associated with Loeys-Dietz syndrome. INTERVENTIONS: Although infection was properly controlled with appropriate antimicrobial treatment, his renal dysfunction did not improve. A short-term inclusion of low-dose corticosteroid significantly benefit without introducing harm. OUTCOMES: He partly recovered from renal injury. LESSONS: In patients with glomerulonephritis triggered by a long-duration infection, low-dose corticosteroid therapy may be considered when renal dysfunction secondary to nephritis does not improve after appropriate antimicrobial treatment.

Cryopreserved Allograft in the Management of Native and Prosthetic Aortic Infections.

BACKGROUND: The management of patients with aortic native and prosthetic infections is associated with significant morbidity and mortality. We describe a single-center experience with the use of cryopreserved allografts for the treatment of aortic infections, and compare outcomes with rifampin-soaked grafts and extra-anatomic bypass. METHODS: We retrospectively reviewed all patients who underwent an operative intervention for aortic infection at our tertiary care center from August 2007 to August 2017. Demographic data, preoperative work-up, procedural details, and outcomes were collected for each treatment modality. RESULTS: Thirty-two patients had aortic revascularization for aortic infection. Seventeen patients had cryopreserved allografts, 10 had rifampin-soaked grafts, and 5 had extra-anatomic bypass. Sixteen patients (50%) had native aortic infection and 16 patients (50%) had prosthetic aortic infection. Eighteen had involvement of the infrarenal abdominal aorta, 12 of the paravisceral aorta, and 2 of the descending thoracic aorta. Early mortality was 5.9% (1/17) for the cryopreserved group, 10% (1/10) for the rifampin-soaked group, and 40% (2/5) for the extra-anatomic bypass group. Early graft-related complications occurred in 1 patient (cryopreserved group). Mean follow-up was 34.8 months. Late death occurred in 4 patients with cryopreserved allografts, 2 with rifampin-soaked grafts and none with extra-anatomic bypass. Late graft-related complications occurred in 4 patients (cryopreserved group). Only 1 patient had recurrence of aortic infection (cryopreserved group) and 2 patients had limb loss (1 from the cryopreserved group and 1 from the rifampin-soaked group). At 1 month, 6 months, 1 year, and 3 years, estimated survival for patients with cryopreserved allografts was 94%, 82%, 75%, and 64%, respectively. CONCLUSIONS: The management of aortic infections is challenging. In patients who do not need immediate intervention, in situ aortic reconstruction with cryopreserved allografts is a viable treatment modality with relatively low morbidity and mortality.

Ruptured infected aneurysm of the thoracic aorta associated with tunneled dialysis catheter-related methicillin-resistant Staphylococcus aureus bacteremia in a hemodialysis patient.

Patients with an indwelling tunneled dialysis catheter (TDC) for hemodialysis access are at a high risk of developing methicillin-resistant Staphylococcus aureus (MRSA) infection. MRSA bacteremia complications rarely include infected aneurysm. Here, we report the first case of an infected thoracic aneurysm associated with TDC-related MRSA bacteremia. An 86-year-old Japanese male with a TDC for hemodialysis access developed TDC-related MRSA bacteremia. Intravenous vancomycin was initiated, and the TDC was removed on day 3. Despite removal of the catheter and initiation of vancomycin treatment, MRSA bacteremia persisted. Chest computed tomography (CT) showed no aneurysm; however, calcification of the thoracic aorta was detected on admission. The patient subsequently developed hemosputum. CT revealed a thoracic aneurysm, which turned out to be caused by MRSA bacteremia. The patient eventually died because of the rupture of the infected aneurysm, as confirmed by autopsy. This report demonstrates TDC management in a patient with TDC-related MRSA bacteremia and the importance of investigating a metastatic infection to a calcified artery if bacteremia persists.

Graft-Sparing Strategy for Thoracic Prosthetic Graft Infection.

OBJECTIVE: Thoracic prosthetic graft infection is a rare but serious complication with no standard management. We reported our surgical experience on graft-sparing strategy for thoracic prosthetic graft infection. METHODS: This study included patients who underwent graft-sparing surgery for thoracic prosthetic graft infection at Matsubara Tokushukai Hospital in Japan from January 2000 to October 2017. RESULTS: There were 17 patients included in the analyses, with a mean age at surgery of 71.0 ± 10.5 years; 11 were men. In-hospital mortality was observed in five patients (29.4%). CONCLUSIONS: Graft-sparing surgery for thoracic prosthetic graft infection is an alternative option particularly for early graft infection after hemiarch replacement.

Management of the infected aortic endograft.

Although the incidence of abdominal and thoracic aortic endograft infection is infrequent, ranging between 0.2% and 5%, stent-graft infection carries significant morbidity and mortality and exemplifies a formidable therapeutic challenge. The treatment goal is to eradicate the infectious process by endograft explantation, regional tissue debridement, and arterial reconstruction by either an extra-anatomic or in situ grafting procedure using autologous vein, cryopreserved allograft, or antibiotic-soaked prosthetic grafts. Successful treatment should maintain normal arterial perfusion to the visceral arteries and lower extremities. Important treatment adjuncts included antibiotic therapy based on cultures, specific bacterial isolates, and coverage of the repair or aortic stump using an omental wrap. Nonoperative treatment in patients with severe comorbidities that preclude endograft explantation may be appropriate in the setting of low-grade biofilm infection. Percutaneous drainage of the perigraft abscess followed by continuous antibacterial irrigation of the cavity can be utilized, but is associated with a high clinical failure rate.

How to best treat infectious complications of open and endovascular thoracic aortic repairs.

Infectious complications of open and endovascular procedures for descending thoracic aortic disease are relatively rare, affecting 1% to 6% of treated patients. However, the number of thoracic aortic procedures, especially endovascular, is increasing continuously, and infectious complications involving the graft or endograft have been observed more frequently in recent years. Several causative factors may play a role in thoracic aortic prosthetic infections, including hematogenous seeding, local bacterial translocation, and iatrogenous contamination. In addition, the development of a fistula between the aortic graft and the esophagus or the bronchial tree is a common associated finding, representing a dramatic event that further increases mortality rates and requires multidisciplinary management. Treatment of these conditions is demanding, often including a number of pharmacological, surgical, and endovascular options. Because there are several different surgical strategies and timing modalities that are chosen according to the surgeon's experience, the results of different treatment options are difficult to summarize, and no consensus exists on a standardized paradigm of treatment. In this review, published reports regarding clinical outcomes related to thoracic graft and endograft infections are discussed, including our personal experience with surgical and endovascular management of this condition.

A Fatal Aortic Arch Rupture Due to Descending Necrotizing Mediastinitis in a 24-year-old Woman.

Descending necrotizing mediastinitis (DNM) is a life-threatening disease which often develops from a purulent infection of the oral cavity and is associated with high rates of mortality. Here we report the case of a young patient who died from an aortic arch rupture in context of DNM developed from an odontogenic infection caused by Prevotella buccae. Based on the current knowledge on this very rare vascular complication, we discuss factors that may have contributed to this fatal issue and future issues to optimize care provided to patients.

Endovascular Management of Concomitant Thoracic and Abdominal Aortic Ruptures Resulting from Brucellosis Aortitis.

BACKGROUND: Acute aortic symptomatology is an unusual manifestation of Brucella melitensis infection. We present a rare case of acute multifocal thoracic and abdominal aortic ruptures arising from Brucellosis aortitis managed exclusively with endovascular surgery. METHODS: A 71-year-old Hispanic male with a history of atrial fibrillation and prior stroke on chronic anticoagulation presented with shortness of breath and malaise. In addition, he had been treated approximately 1 year previously in Mexico for B. melitensis bacteremia after eating fresh unpasteurized cheese. Computed tomography (CT) angiography demonstrated an acute rupture of the descending thoracic aorta just proximal to the celiac trunk and synchronous rupture at the abdominal aortic bifurctation. RESULTS: The patient was taken emergently to the hybrid operating room, where synchronous supraceliac thoracic aorta and abdominal aortoiliac stent grafts were deployed under local anesthesia. Completion angiography demonstrated total exclusion of the thoracic and abdominal extravasation with no evidence of endoleak. Twenty hours postoperatively, the patient became acutely obtunded and hypotensive. Repeat CT angiography demonstrated contrast extravasation at the level of the excluded aortic bifurcation. Emergent angiography confirmed a type II endoleak with free extraluminal rupture. Multiple coils were placed at the level of the aortic bifurcation between the left limb of the stent graft and the aortic wall to tamponade the endoleak. No further extravasation was noted on final aortography. Postoperatively, blood cultures confirmed the diagnosis of B. melitensis. The patient was treated with systemic doxycycline, gentamicin, and rifampin. Resolution of the acute event occurred without additional sequelae and he was discharged from the hospital to a rehabilitation facility. CONCLUSIONS: Concomitant multifocal aortic ruptures arising from Brucellosis aortic infection is a very rare event. In this case, the patient was successfully treated with thoracic and abdominal endovascular stent-graft exclusion, coiling, and long-term targeted antibiotics.

Thoracic Aortic Graft Infections Secondary to Propionibacterium Species: Two Cases and Review of the Literature.

Aortic graft infections are a rare occurrence, most commonly secondary to gram-positive organisms (Staphylococcus and Streptococcus species). We present 2 cases of thoracic aortic graft infections secondary to anaerobic bacteria, Propionibacterium species. The first case, a 40-year-old male, was found to have an anastomotic aneurysm at the distal anastomosis of a previous thoracoabdominal aneurysm repair. During the open repair of his anastomotic aneurysm, the original graft was not incorporated and cultures later speciated Propionibacterium acnes The second case is a 44-year-old male with a history of abdominal aortic coarctation that was repaired with a thoracic aorta to aortic bifurcation graft as a child who presented with flank pain and was found on imaging to have fluid around his bypass graft. His operating room (OR) cultures also grew out Propionibacterium species. Both patients were treated with graft excision, revascularization, and long-term antibiotics. Anaerobic bacteria are a rare cause of aortic graft infections. Upon review of the literature, these are the first 2 cases of thoracic aortic graft infections secondary to Propionibacterium species. The cultures for both patients took almost a week to speciate, highlighting the importance of following cultures long term. Anaerobic bacteria should be recognized as a cause of latent graft infections.

Treatment and outcomes of aortic endograft infection.

OBJECTIVE: This study examined the medical and surgical management and outcomes of patients with aortic endograft infection after abdominal endovascular aortic repair (EVAR) or thoracic endovascular aortic repair (TEVAR). METHODS: Patients diagnosed with infected aortic endografts after EVAR/TEVAR between January 1, 2004, and January 1, 2014, were reviewed using a standardized, multi-institutional database. Demographic, comorbidity, medical management, surgical, and outcomes data were included. RESULTS: An aortic endograft infection was diagnosed in 206 patients (EVAR, n = 180; TEVAR, n = 26) at a mean 22 months after implant. Clinical findings at presentation included pain (66%), fever/chills (66%), and aortic fistula (27%). Ultimately, 197 patients underwent surgical management after a mean of 153 days. In situ aortic replacement was performed in 186 patients (90%) using cryopreserved allograft in 54, neoaortoiliac system in 21, prosthetic in 111 (83% soaked in antibiotic), and 11 patients underwent axillary-(bi)femoral bypass. Graft cultures were primarily polymicrobial (35%) and gram-positive (22%). Mean hospital length of stay was 23 days, with perioperative 30-day morbidity of 35% and mortality of 11%. Of the nine patients managed only medically, four of five TEVAR patients died after mean of 56 days and two of four EVAR patients died; both deaths were graft-related (mean follow-up, 4 months). Nineteen replacement grafts were explanted after a mean of 540 days and were most commonly associated with prosthetic graft material not soaked in antibiotic and extra-anatomic bypass. Mean follow-up was 21 months, with life-table survival of 70%, 65%, 61%, 56%, and 51% at 1, 2, 3, 4, and 5 years, respectively. CONCLUSIONS: Aortic endograft infection can be eradicated by excision and in situ or extra-anatomic replacement but is often associated with early postoperative morbidity and mortality and occasionally with a need for late removal for reinfection. Prosthetic graft replacement after explanation is associated with higher reinfection and graft-related complications and decreased survival compared with autogenous reconstruction.

SIV/SHIV Infection Triggers Vascular Inflammation, Diminished Expression of Krüppel-like Factor 2 and Endothelial Dysfunction.

BACKGROUND: Human immunodeficiency virus (HIV) infection is associated with increased risk of thromboembolic and cardiovascular comorbid conditions. Although systemic inflammation is linked to cardiovascular risk, direct evidence of vascular inflammation and endothelial dysfunction is lacking. METHODS: We examined by immunofluorescence microscopy thoracic aortas from 16 simian immunodeficiency virus (SIV)- or simian-human immunodeficiency virus (SHIV)-infected and 16 uninfected rhesus macaques. RESULTS: Focal endothelial proliferation and subendothelial inflammatory cells were found in sections of all infected animals, compared with minimal changes in sections from the 16 uninfected controls. In the infected animals, we detected increased endothelial levels of bacterial 16s ribosomal DNA as well as increased subendothelial accumulation of CD68(+) monocytes/macrophages (P< .001) and CD8(+) T lymphocytes (P< .001). Endothelial dysfunction was manifested by decreased levels of endothelial nitric oxide synthase (P< .005) and Krüppel-like factor 2 (KLF2) (P< .005). KLF2 expression was decreased in primary human aortic endothelial cells exposed to bacterial lipopolysaccharide or to oxidized low-density lipoprotein in vitro, and this could be prevented by simvastatin. CONCLUSIONS: SIV and SHIV infection lead to endothelial inflammation, dysfunction, and decreased KLF2 expression reflecting early atherosclerotic changes. Translocated bacterial components and lipid oxidation products may induce endothelial dysfunction in HIV infection that could be prevented by statin treatment.