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Streptococcus Equi Causing Mycotic Aortic Aneurysm With Rupture
Abdullah Khan, MD, Fachreza Aryo Damara, MD, Patricia Bartley, MD, Lalithaa Murugan, MD, Francis Caputo, MD, Sean Lyden, MD, Lee Kirksey, MD.
Cleveland Clinic, Cleveland, OH, USA.
DEMOGRAPHICS: A 72-year-old white man works at a farm with exposure to horses. HISTORY: Patient with medical history of non-Hodgkin's lymphoma, Waldenström's macroglobulinemia, chronic kidney disease (CKD) stage 3, benign prostatic hyperplasia, and gastroesophageal reflux disease, presented to the ER with abdominal and back pain. A CT scan showed two saccular aneurysms: one 5.0 cm posterior to the right renal artery takeoff and another 2.3 cm in the infrarenal aorta, with periaortic stranding and rupture of a pararenal mycotic aneurysm. Labs showed leukocytosis and anemia. PLAN: The patient was started on broad-spectrum antibiotics. An emergency open left retroperitoneal repair of the pararenal aortic aneurysm was performed using a rifampin-soaked Gelsoft™ tube graft with a left renal artery bypass, all wrapped with an omental flap. The culture of the aortic specimen grew Streptococcus equi, and IV ceftriaxone was started based on sensitivity. The patient improved and was discharged on POD8 with IV ceftriaxone. The patient was readmitted on POD 11 with a pseudoaneurysm at the proximal aortic anastomosis. He was deemed not a candidate for thoracoabdominal repair with partial left heart bypass. Laboratories showed thrombocytosis (820) & leukocytosis (25). A Gore Excluder® conformable cuff was extended proximal to the level of the celiac trunk with a Viabahn VBX® superior mesenteric artery snorkel. The patient stabilized after a complex hospital course and was discharged to acute rehab. He recovered well and continued on long-term oral amoxicillin. He remains free of aneurysm associated pathology. DISCUSSION: Streptococcus equi is a gram-positive, beta-hemolytic bacterium from Lancefield group C. It commonly infects animals and rarely causes human infections. Exposure to raw dairy products and animals, especially horses, are common sources. Less than twenty cases have been reported in the literature to date. Mycotic abdominal aortic aneurysms with Streptococcus equi are particularly rare and pose a significant risk of rupture and mortality if left untreated. Management typically involves a combination of surgical resection with various conduit options and antibiotic therapy; long-term use of antibiotics improves survival. Regardless of treatment, mortality is high. This case underscores the need for society recommendations to guide management of mycotic aortic aneurysms.
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