Mycotic aortic aneurysm due to clostridium septicum and diverticulitis

Abstract

Mycotic aortic aneurysms represent about 1% of abdominal aortic aneurysms. Typically seen in the setting of immunocompromise, mycotic aneurysms can affect younger patients and those without typical vascular risk factors. Common causative organisms are Staphylococcus, Streptococcus, or Salmonella spp.; however, mycotic aneurysms caused by less common pathogens have been described. One such rare species is Clostridium septicum and if not treated quickly and aggressively with surgery and antibiotics, infectious aortitis by C. septicum is fulminant and carries a mortality rate approaching 100%. Many cases of C. septicum aortitis have been associated with colonic malignancies, and opportunistic infection is thought to occur from the combination of a favorable tumor microenvironment and damaged gastrointestinal mucosa. We present an unusual case of a ruptured mycotic infrarenal abdominal aortic aneurysm due to C. septicum associated with diverticular disease in a 79-year-old male.