Ann Thorac Surg 1996;62:1835-1837
© 1996 The Society of Thoracic Surgeons
Case Report
Mycotic Aneurysm of the Thoracic Aorta Caused by Clostridium septicum
David P. Murphy, MD,
David B. Glazier, MD,
Tyrone J. Krause, MD
Division of Cardiac Surgery, Department of Surgery, Robert Wood Johnson Medical School, New Brunswick, New Jersey
Accepted for publication June 20, 1996.
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Abstract
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We describe a case of a 78-year-old man who presented with a mycotic aneurysm of the thoracic aorta caused by Clostridium septicum and underwent successful resection. There are only 3 cases of mycotic aneurysms caused by Clostridium septicum reported in the literature. Clostridium septicum infections have been shown to have a high association with gastrointestinal and hematologic malignancies. All patients with Clostridium septicum infections, therefore, require a search for gastrointestinal lesions, as they may represent a source of persistent bacteremia. This patient had no malignant lesions but did have multiple benign sigmoid polyps.
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Introduction
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Mycotic aneurysms have yielded various organisms. Gram-positive organisms, such as staphylococci, and gram-negative organisms, particularly Salmonella, are among the most common. Clostridium septicum is an unusual cause of a mycotic aneurysm, but one with specific implications as the organism is usually present only in the setting of a gastrointestinal malignancy. This report describes a thoracic aneurysm caused by C septicum, which was successfully managed surgically.
A 78-year-old man with a medical history significant only for hypertension presented to the emergency room acutely short of breath and febrile. He gave a history of progressive dysphagia over the preceding several months. There was no history of preceding trauma. On admission his temperature was 39.3°C. Laboratory tests revealed a white blood cell count of 30,400/µL (normal, 4,000 to 11,000/µL). Chest roentgenogram revealed a widened mediastinum and the presence of mediastinal air (Fig 1
). A computed tomographic scan of the chest demonstrated an aneurysm of the descending thoracic aorta with surrounding air (Fig 2). An esophagogram showed external compression of the upper esophagus, but no perforation (Fig 3). Blood cultures yielded C septicum. A preoperative diagnosis of an infected thoracic aneurysm was made.
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Fig 2. . Computed tomographic scan of the chest showing a large thoracic aneurysm with surrounding air.
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The patient was transferred to this institution, where he underwent a left lateral thoracotomy. There was a 10-cm aortic aneurysm just distal to the subclavian artery, which appeared as an inflamed mass, with fibrinous and necrotic debris. Femorofemoral bypass was begun, and the aneurysm was resected during circulatory arrest. On close inspection it was apparent that the aneurysm had eroded through a portion of the esophagus, and the midesophagus demonstrated a 3-cm-long perforation. This necessitated esophagectomy and mucous fistula formation. The patient was treated with penicillin and clindamycin.
Pathologic examination revealed acute inflammatory exudate consistent with a mycotic aneurysm that had eroded through the esophagus. There was no evidence of malignancy within the esophageal specimen.
Because of the known association of C septicum infections and gastrointestinal malignancies, colonoscopy was performed and revealed several benign sigmoid polyps but no malignant lesions. There was no evidence of any hematologic disorder. At 6 months postoperatively the patient is home without evidence of recurrent clostridial infection and is planned to undergo esophageal reconstruction using colonic interposition.
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Comment
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Osler first coined the term "mycotic aneurysm" in 1885 in his description of a mushroom-shaped aneurysm occurring in the setting of endocarditis [1]. Since then the term has been broadened to include all aneurysms with an infectious component.
A mycotic aneurysm may result from one of four mechanisms: (1) direct trauma with contamination, (2) local extension of an infected focus (3) septic microemboli to bifurcation points of smaller vessels or vasa vasorum of larger vessels (the mechanism of mycotic aneurysms associated with endocarditis), and (4) hematogenous seeding from a remote focus [2]. Those arising from the last mechanism have also been termed primary mycotic aneurysms and by definition occur in the absence of local infection or an intravascular focus such as infectious endocarditis [3]. These originate when circulating bacteria from a remote source become implanted on abnormal intima such as that of an atherosclerotic or aneurysmal vessel. The presence of atherosclerosis makes the thoracic and abdominal aorta the most frequent targets [2]. The source of bacteremia in many primary mycotic aneurysms remain unknown, as in the case we presented.
Clostridium septicum rarely causes infections in humans and is most commonly associated with myonecrosis (gas gangrene). Clostridium septicum as a cause of mycotic aneurysms is extremely rare. We have found only 3 such cases reported in the literature [4–6]. Two cases involved the thoracic aorta and 1 the abdominal aorta.
Clostridium septicum infections are frequently associated with malignant neoplasms, particularly hematologic and gastrointestinal, either known or occult. The association has been reported by several authors since it was first recognized in 1969 [7]. Kornbluth and associates [8] reported an associated malignancy in 81% of patients with C septicum, and other studies have reported similar findings [9]. Primary colon cancers, and cecal lesions in particular, have the highest association. Clostridium septicum infections also occur in the presence of hematologic malignancies. These patients demonstrate leukemic infiltration of the ileum and colon, necrotizing colitis, or mucosal ulceration secondary to radiotherapy or chemotherapy [9, 10]. A disruption of the colonic mucosa, therefore, seems to be the common port of entry for C septicum. Frequently the presence of a malignant lesion is unknown and the patient instead presents with a spontaneous C septicum infection.
Clostridium septicum is an organism rarely encountered by the cardiovascular surgeon. The unique implications of this isolate, however, warrant attention. Patients with C septicum infections demand a thorough search for an associated gastrointestinal malignancy once the life-threatening issues are addressed. Such lesions represent a source of persistent bacteremia and can lead to infections of new prosthetic grafts [6]. Evaluation of our patient revealed several benign polyps but no malignant lesions. Interestingly, 1 of the other 3 previously reported cases also reports benign polyps as a possible source [6]. Whether this was the source of C septicum in these patients is unclear.
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Footnotes
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Address reprint requests to Dr Krause, Division of Cardiac Surgery, Robert Wood Johnson Medical School, One Robert Wood Johnson Place, New Brunswick, NJ 08903.
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References
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- Osler W. The Gulstonian Lectures on malignant endocarditis. Br Med J 1885;1:467–70.[Free Full Text]
- Hoeprich PD. ed. Infectious diseases. 5th ed. Philadelphia: Lippincott, 1994:1255–8.
- Bennett DE. Primary mycotic aneurysms of the aorta. Arch Surg 1967;94:758–65.[Abstract/Free Full Text]
- Semel L, Aikman WO, Parker FB, Marvasti MA. Nontraumatic clostridial myonecrosis and mycotic aneurysm formation. N Y State J Med 1984;84:195–6.[Medline]
- Brahan RB, Kahler RC. Clostridium septicum as a cause of pericarditis and mycotic aneurysm. J Clin Microbiol 1990;28:2377–8.[Abstract/Free Full Text]
- Hurley L, Howe K. Mycotic aortic aneurysm infected by Clostridium septicum-a case history. Angiology 1991;42:585–9.
- Alpern RJ, Dowell VR. Clostridium septicum infections and malignancy. JAMA 1969;209:385–8.[Abstract/Free Full Text]
- Kornbluth AA, Danzig JB, Bernstein LH. Clostridium septicum infection and associated malignancy: report of two cases and review of the literature. Medicine (Baltimore) 1989;68:30–7.[Medline]
- Pelfrey TM, Turk RP, Peoples JB, Elliott DW. Surgical aspects of Clostridium septicum septicemia. Arch Surg 1984;119:546–50.[Abstract/Free Full Text]
- Dosik GM, Luna M, Valdivieso M, et al. Necrotizing colitis in patients with cancer. Am J Med 1979;67:646–56.[Medline]
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Abstract
Introduction
