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Bacteroides fragilis aortic arch pseudoaneurysm: case report with review
© Lee et al; licensee BioMed Central Ltd. 2008
Received: 18 January 2007
Accepted: 20 May 2008
Published: 20 May 2008
We present a case of 58-year-old woman with underlying diabetes mellitus, hepatitis C virus-related liver cirrhosis, and total hysterectomy for uterine myoma 11 moths ago, who was diagnosed ruptured aortic arch mycotic pseudoaneurysm after a certain period of survey for her unknown fever cause. After emergent surgery with prosthetic graft interposition, all her blood cultures and tissue cultures revealed pathogen with Bacteroides fragilis. Although mycotic aneurysms have been well described in literatures, an aneurysm infected solely with Bacteroides fragilis is unusual, with only eight similar cases in the literature. Here we reported the only female case with her specific clinical and management course and summarized all reported cases of mycotic aneurysm caused by Bacteroides fragilis to clarify their conditions and treatments, alert the difficulty in diagnosis, and importance of highly suspicious.
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.
Although the first reported mycotic aneusym was introduced in 1885 by Sir Willam Osler for fungal vegetations in the aortic arch complicated by endocarditis, mycotic aneurysm remains one of the most life-threatening conditions in the field of vascular surgery. The prevalence of the mycotic type among all forms of aortic aneurysm is estimated about 1–2.7% [1, 5]. The most common infection sites are the femoral artery and abdominal aorta, followed by the thoracoabdominal and thoracic aorta [1, 6]. Essentially, three mechanisms of mycotic aortic aneurysm have been implicated, namely, septic embolization that usually is secondary to bacterial endocarditis; direct or lymphatic spread from an adjacent infected focus; and hematogenous seeding of the arterial wall during bacteremia from a distant focus [1, 3, 4].
Reported cases of mycotic aneurysm infected by Bacteroids fragilis
Expired, 14 days
Chronic back pain
Sudden back pain
Low back pain
Expired, on table
Extra anatomic bypass
The conventional strategy for the treatment of mycotic aneurysm is prompt surgical intervention followed by long term antibiotic therapy, which is essential to control systemic sepsis and to achieve cardiovascular stability. Antibiotics alone are not sufficient, and complete excision of the affected aorta is the key to curative treatment [1, 10, 14]. However, the surgical procedures are associated with substantial mortality rates associated with the risk of recurrent infection and the survival was influenced not by the type of reconstruction but by the status of aneurismal rupture . The use of homograft, antibiotic-coated grafts to reduce the source of infection, or of a coated endoprosthesis to release antibiotics into the blood stream, have been proposed for the successful management . However, it depends on the availability of hospital. Several authors advocated for endovascular stent-graft treatment with no mortality in small case reports . The main advantages of this minimally invasive approach are the reduction of surgical trauma as well as minimal hemodynamic alterations. It may ultimately become the standard of care if results prove equivalent to open intervention. Even though, the difficult application in ascending aorta to arch region, the possibility of stent graft infection, and the unaffordable product prices are major considerations for their usage. In addition, fever presentation (3/4,75%), indicated active process persisted, in such patients seems a terrible signature for most of patients would have poor prognosis even under aggressive treatment.
In conclusion, it should be noted that Bacterioides fragilis is a rare causative pathogen and the primary source of this bacterium is often undetermined. A higher clinical awareness of this disease, leading to early computed tomography evaluation and prompt surgical intervention under appropriate and intensive antibiotic therapy, appears to offer the best chance of survival in patients with this difficult condition.
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