CLOSTRIDIAL MYCOTIC ANEURYSM LEADING TO EMPHYSEMATOUS AORTITIS: A CASE REPORT

Abstract

SESSION TITLE: Medical Student/Resident Chest Infections Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Emphysematous aortitis (EA) is a rare consequence of mycotic aneurysm associated with high morbidity and mortality. Most cases have been linked to infection with Staphylococcus species. This case reports clostridial bacteremia leading to arterial myonecrosis and subsequent aortitis. CASE PRESENTATION: The patient was a 66-year-old male with a past medical history of end stage renal disease with an arterio-venous fistula, hypertension, and diabetes who presented with tachycardia, tachypnea, and hypertension for one week. He also had leukocytosis of 23,000/µL with elevated inflammatory markers including a D-dimer of 4700 ng/mL. Computed tomography showed air within the walls of the thoracic aorta and in the periaortic soft tissue with extension from the aortic arch to the mid descending thoracic aorta consistent with aortitis. There was also involvement in the periaortic mediastinal fat and a loculated large left pleural effusion concerning for empyema. Blood cultures revealed Clostridium subterminale, however, gastrointestinal work up did not reveal esophageal or colonic malignancy, or mucosal trauma. He then underwent ascending aorta and distal arch reconstruction. Unfortunately, his post-operative course was complicated by hypotension unresponsive to multiple vasopressors and asystole. Post-mortem aortic tissue cultures were positive for Clostridium innocuum. DISCUSSION: EA is a rare but often fatal sequelae of mycotic aneurysms and has been hypothesized to occur through arterial injury (trauma), bacteremic seeding, contiguous infection, or septic emboli. Risk factors include arterial injury (Intravenous drug use/iatrogenic interventions), infection, immunosuppression, atherosclerosis, and pre-existing aneurysm. Mycotic aneurysms comprise only 0.5% to 1.3% of all aneurysms, and Clostridium species only comprise 0.7% of those cases. C. innocuum aortitis appears to present radiographically similar to other types of Clostridium aortic aneurysms, in which periaortic gas was found to be present in 92.6% of cases. Curiously, the patient was found to have bacteremia with a separate Clostridium species (C. subterminale) from the one found in the aortic wall (C. innocuum). Some reported cases of C. subterminale bacteremia was associated with mucosal damage. The patient’s negative endoscopy findings may suggest a different source of infection for both Clostridium species, possibly via the patient's arterio-venous fistula leading to infection within the atherosclerotic plaques of the aorta. CONCLUSIONS: Emphysematous aortitis is a rare complication of anaerobic infection. A high suspicion should be present in the differential based on radiographic and clinical findings as well as patient risk factors. Reference #1: Sörelius K, Budtz-Lilly J. Systematic Review of the Management of Mycotic Aortic Aneurysms. Eur J Vasc Endovasc Surg. 2019;58(3):426-435. doi:10.1016/j.ejvs.2019.05.004 Reference #2: Ito F, Inokuchi R, Matsumoto A, et al. Presence of periaortic gas in Clostridium septicuminfected aortic aneurysm AIDS in early diagnosis: A case report and systematic review of the literature. J Med Case Rep. 2017;11(1). doi:10.1186/s13256-017-1422-0 Reference #3: Seder CW, Kramer M, Long G, Uzieblo MR, Shanley CJ, Bove P. Clostridium septicum aortitis: Report of two cases and review of the literature. J Vasc Surg. 2009;49(5):1304- 1309. doi:10.1016/j.jvs.2008.11.058 DISCLOSURES: No relevant relationships by Thomas Ng, source=Web Response No relevant relationships by Christopher Pham, source=Web Response