Infectious endocarditis (IE) is a life-threatening infection that can lead to cardiac dysfunction, systemic embolism and mortality. Most cases are caused by gram-positive and HACEK (haemophilus types, aggregating bacteria types, Cardiobacterium hominis, Eikenella corrodensand Kingella species) organisms. Escherichia coli, a gram-negative enteral bacterium, is a rare cause of endocarditis due to the lack of virulence factors that promote adhesion to the endocardial structures. Herein we report the first case of IE complicated by a paravalvular mycotic pseudoaneurysm of the left ventricle caused by E coli post-transcatheter aortic valve replacement (TAVR).
An 88-year-old male underwent TAVR five years prior to this current admission for aortic stenosis, followed by transcutaneous pacemaker insertion three years later for symptomatic bradycardia. In addition, the patient had a history of transitional cell carcinoma (TCC) of the urinary bladder and had undergone a radical cystectomy with ileal cystectomy for urinary diversion 20 years earlier.
The patient presented for one week with fever and general deterioration. On admission he was clinically stable with a high fever (38.9°C). Physical examination revealed no focal signs of infection or peripheral signs of IE. Urine and blood cultures were positive for E coliThus, a preliminary diagnosis of urinary tract infection was suggested and antibiotic treatment with ceftriaxone was initiated based on susceptibility results. Significant clinical improvement was observed after one week of antibiotic treatment, serial blood cultures were obtained and sterile, and he was discharged home. Three days later, the patient was readmitted with similar symptoms, including fever and general deterioration.
Lab results at his readmission showed an increased white blood cell count and C-reactive protein. Kidney function tests were normal; however, metabolic acidosis was noted. Urinalysis was positive for leukocytes and recurrent growth of E coli was confirmed in urine and blood cultures. Computed tomography (CT) of the head, chest and abdomen revealed no apparent source of infection and ultrasound of the abdomen was unremarkable.
During his second hospitalization, he developed a transient loss of vision in his right eye. Magnetic resonance imaging of the brain (MRI) revealed an acute stroke in the area of the left posterior cerebral artery with small other infarcts suggesting the suspicion of embolism, strongly suggestive of a cardiac source (Figure 1). Therefore, the patient underwent two-dimensional transthoracic echocardiography (TTE), which revealed an echogenic mass in the right atrium that predicted to the right ventricle (Figure 2 and videos 1, 2).
Given this finding, a cardiac CT was performed showing a posterior pseudoaneurysm of the aortic valve, bulging from the left ventricular outflow tract (LVOT) to the right atrioventricular groove (Figure 3).
Fluorodeoxyglucose (FDG) positron emission tomography (PET) showed high FDG uptake around the aortic valve and into the pseudoaneurysm with no evidence of pacemaker lead infection (Figure 4).
A multidisciplinary meeting, including cardiac surgeons, cardiologists and infectious disease physicians, was conducted to discuss treatment options for the patient with a left ventricular and paravalvular-infected pseudoaneurysm after TAVR. Due to its extremely high surgical risk, it was decided to continue conservative therapy, including lifelong antibiotic therapy. The patient completed three months of intravenous ceftriaxone followed by oral ciprofloxacin according to the results of bacterial susceptibility testing.
Follow up
At a three-month follow-up, the patient had no signs of infection or hemodynamic compromise. However, seven months after being diagnosed with IE, he was re-admitted to the hospital for fever and blood and urine cultures were again positive for E coli despite oral antibiotic therapy. Unfortunately, resistance tests showed a broad spectrum beta-lactamase (ESBL) profile with resistance to ciprofloxacin; therefore he was treated with intravenous ertapenem. TTE was performed and showed a decrease in mass size. During his hospitalization, the patient developed a Clostridioides difficile infection, and despite appropriate antibiotic therapy, his condition continued to deteriorate and he died.
E coli is a gram-negative gut bacteria and is a rare cause of IE, accounting for less than 0.5% of cases [1]. In 2018, Akuzawa et al. [2] reported 32 cases of endocarditis caused by: E coli. Since then 16 reports from E coli IE on native or prosthetic valves have been added. Common comorbidities associated with IE include diabetes mellitus, a history of malignancy, excessive alcohol consumption, kidney disease, and steroid treatment. E coli IE has been shown to be more common in patients with prosthetic valves; the mitral valve appears to be most affected, followed by the aortic valve [2].
The low incidence of E coli IE has been attributed to the lack of virulence factors that promote attachment to the endocardial heart valves and the existence of antibodies against E coli in normal serum [3]. The death rate of E coli IE (21%) is higher than IE by other gram-negative bacteria such as the HACEK group (4%) [1,4]. In general, urinary tract infections are the most common source of: E coli I.E [2].
The incidence of IE associated with TAVR is estimated to be 0.8-1.4% [5]. A recent meta-analysis found no differences in the overall incidence of IE between surgical aortic valve replacement (SAVR) and TAVR [6].
The data in the literature on the optimal management of E coli IE, whether surgical or conservative, are scarce. In a systematic review of post-TAVR IE, Amat-Santos et al. [7] reported that 60% of patients received medical treatment, including those with IE-related complications. The overall in-hospital mortality rate was 34% with no significant differences between surgical and conservative approaches. Percutaneous recovery from IE-associated complications may be considered in some patients who are not surgical candidates. Ninos et al. [8] reported a case of successful repair of healed mitral valve endocarditis using the MitraClip device (Abbott, Abbott Park, IL), despite the presence of large mobile vegetation. Meijer et al. [9] reported a case of successful vegetation debriding in a high-risk patient using aspiration-based therapy. Finally, Chan et al. [10] presented an alternative approach for the treatment of mitral valvular valve by valve-in-valve transcatheter mitral valve replacement with an embolic protection device, followed by long-term suppressive oral antibiotic therapy. These reports offer promising therapeutic strategies for percutaneous recovery from complications related to IE in high-risk and non-surgical candidates.
Enteric gram-negative bacteria, in particular E coli, is a rare cause of IE, which can be associated with serious complications, especially after cardiac interventions, such as TAVR. To our knowledge, we report the first case of post-TAVR IE complicated by a mycotic pseudoaneurysm of the left ventricle caused by E coli. In addition, we emphasized the importance of multimodal imaging in patients with cardiac prostheses or devices to promptly identify and treat IE and its associated complications. This case should make clinicians more aware of such cases in high-risk patients.