Mycotic Abdominal Aortic Aneurysm Caused by Streptococcus equi

Abstract

Streptococcus equi is a bacterium common in equine species and an uncommon pathogen in humans. Reported human infections can be severe and include meningitis, septic arthritis, and endocarditis. We report the case of a 64-year-old male who S. equi with several months of constitutional symptoms, back pain, and abdominal pain. Imaging demonstrated a large abdominal aortic aneurysm with a contained retroperitoneal rupture, with cultures from the aneurysm and blood cultures both positive for S. equi. The patient was successfully treated with open repair and placement of a Dacron graft and intravenous antibiotics and will remain on lifelong antibiotic prophylaxis.

Keywords: abdominal aortic aneurysm; mycotic aneurysm; streptococcus equi.

Figure 1. (A) Axial view demonstrating circumferential calcification of the infrarenal abdominal aorta, with normal appearing diameter of aortic lumen, with associated posterior pseudoaneurysm. (B) Coronal view of infrarenal abdominal aorta with large posterior pseudoaneurysm. (C) Sagittal view, posterior pseudoaneurysm, with preserved aortic diameter above and below the arterial defect. Note the compression of the aortic lumen superior to the pseudoaneurysm.