B49-20 A Rare Case of Suspected Mycotic Aneurysm Following Enterococcus Faecalis Endocarditis

Abstract Mycotic aneurysms are uncommon but potentially fatal vascular complications arising from infection of the arterial wall, leading to aneurysmal dilation, wall necrosis, or intramural hematoma. While Staphylococcus aureus, Salmonella spp., and Streptococcus species are the most frequently implicated pathogens, Enterococcus faecalis is a rare cause. Predisposing factors include bacteremia, infective endocarditis, immunosuppression, and intravascular catheters such as PICC lines A 67-year-old woman with a history of diabetes, hypertension, dyslipidemia, and end-stage renal disease on hemodialysis presented to the emergency department with abdominal pain and diarrhea. She was diagnosed with gastroenteritis and discharged with outpatient GI follow-up. Blood cultures taken during the visit later returned positive for Enterococcus faecalis, prompting hospital readmission. A new systolic murmur on exam led to transthoracic and then transesophageal echocardiography, revealing vegetation on the anterior mitral leaflet. She was diagnosed with infective endocarditis, had a PICC line placed, and was discharged on IV ampicillin and ceftriaxone. Two days later, she returned with acute hemoptysis and atypical chest pain. CTA chest ruled out pulmonary embolism but revealed a new penetrating atherosclerotic ulcer (PAU) measuring 2.4 cm with surrounding intramural hematoma in the descending thoracic aorta, a finding absent on imaging just one week earlier. Given her comorbidities and surgical risk, vascular surgery recommended non-operative management with ICU admission for blood pressure and heart rate control. This case highlights a rapidly evolving thoracic aortic lesion following Enterococcus faecalis bacteremia and infective endocarditis, raising strong suspicion for an early-stage mycotic aortic aneurysm or infectious aortitis. The absence of prior aortic abnormality on recent imaging, combined with temporal proximity to bacteremia and mitral valve vegetation, underscores the likely infectious etiology. While mycotic aneurysms typically involve the abdominal aorta and are caused by more common organisms, Enterococcus faecalis remains a rare but important pathogen, particularly in immunocompromised hosts and dialysis patients. Prompt recognition and surveillance are critical, as complications include rupture and death. This case illustrates the need for high clinical suspicion and close imaging follow-up in patients with recent endocarditis who develop new aortic pathology. This abstract is funded by: None