S2250 Polymicrobial Bacteremia With Insidious Gastrointestinal Blood Loss: A Rare Clinical and Endoscopic Manifestation of Secondary Aortoenteric Fistula

Abstract

Introduction: Secondary aortoenteric fistula (AEF) is a rare (0.3-1%) but life-threatening complication after aortic reconstructive surgery with graft. Case Description/Methods: A 68-year-old man with a significant past medical history of type 2 diabetes, COPD, coronary artery disease status post cardiac stent, and aortobifemoral bypass graft performed 10 years ago, was hospitalized with presentations of shortness of breath, chills but no fever, and progressive anemia for the past 14 months. ECG and trend of cardiac enzymes were negative. Chest CT imaging revealed no evidence of pulmonary embolism. He was hemodynamically stable. The pertinent initial labs showed a hemoglobin of 7.5 g/dl (6 months earlier 8.1 g/dl, 14 months earlier 11.9 g/dl) and elevated inflammatory markers (leukocytes 9.8/nL, CRP 85.3 mg/dL) with transient lactic acidosis. Blood cultures on admission showed positive of a variety of microorganisms (Streptococcus sanguis, Lactobacillus paracasei, Candida lusitaniae). Patient reported one episode of red blood per rectum and melena between 1 to 3 weeks before admission. An esophagogastroduodenoscopy (EGD) revealed a large excavated and diverticular-like lesion, without bleeding, in the third part of the duodenum (Figure 1). The initial blood cultures growth and the subsequent blood cultures growth of another microorganism (Enterobacter Cloacae) were considered to have a likely GI source. A PET-CT scan result showed hypermetabolism signal associated with the proximal end of the aortoiliac graft, concerning for infection of the graft itself (Figure 2). The EGD finding was consistent with a secondary aorto-enteric fistula formed by infected aortic graft eroding into duodenum and served as the source of recurrent polymicrobial bacteremia. The patient subsequently underwent explantation of the infected aortobifemoral bypass graft (old graft with fistula to the duodenum), reconstruction with cryopreserved aortoiliac allograft, and resection of small intestine with anastomosis closure of duodenotomy. The removed aortic graft cultures grew a variety of microorganism (Enterococcus faecalis, Enterobacter Cloacae, Candida lusitaniae). The patient was discharged 10 days after the operation and when examined 2 months later he was doing well. Discussion: Secondary AEF should be suspected in patients presenting with unclear source of bacteremia with or without GI bleeding and a history of aortic repair. Clinical suspicion is the most important factor contributing to the right diagnosis.Figure 1.: Esophagogastroduodenoscopy suggested the secondary aortoenteric fistula in the third part of duodenum.Figure 2.: A PET-CT scan showed increased hypermetabolism signal associated with the proximal end of the aortoiliac graft (white arrow), concerning for infection of the graft itself.