Bacteroides fragilis aortic arch pseudoaneurysm: case report with review

Aortic mycotic aneurysm of the thoracic aorta is a rare but fulminant infectious disease and may potentially progress to rupture and death unless early diagnosis and appropriate treatment is instituted [1,2]. The early case reports emphasized endocarditis as the most common source, while hematogenous seeding, direct spreading from a contiguous focus with trauma, lymphatic spreading, and unknown etiology were proposed [1,3,4]. Staphylococcus aureus, nontyphi Salmonella, and Pseudomonas species have been implicated for most causative organisms [1,4]. After the era of antibiotics, the epidemiology of this disease is changing. Bacteroides fragilis was reported as a rare causative pathogen. We describe a case of B. fragilis aortic arch mycotic pseudoaneurysm in a female patient who presented with fever of unknown origin (FUO).A 58-year-old woman with diabetes mellitus, hepatitis C virus-related liver cirrhosis, and total hysterectomy for uterine myoma was admitted to another hospital because of a one-month history of recurrent fevers. Blood cultures were all negative, and a CT scan of the abdomen and pelvis was unremarkable. After a week of intravenous antibiotic treatment, she still presented with mild fever. Owing to that persisted intermittent low-grade fever, she was transferred to our institution and admitted for her fever cause surveying.At admission, she complained of aching sensation on her precordial area while coughing in recent one week. Her initial vital signs revealed a high fever up to 39.5°C, blood pressure of 140/88 mmHg, heart rate of 115 beats/min, and tachypnea of 28/min. The physical examinations were remarkable only for pale conjunctivae and crackles at the right lung base. Laboratory studies showed leukocytosis of WBC count 11,800/μL (74% neutrophils, 13% band forms, 7% lymphocytes, 5% monocytes, and 1% basophils); hemoglobin level 10.8 g/dL; and platelet count 102,000/μL. The C-reactive protein concentration was 182 mg/L. Electrolyte levels and ren