Mycotic Aneurysm

Overview

Mycotic Aneurysms occur due to bacterial infection within the vascular wall and are fairly rare. The inflammation associated with the infectious process results in weakening of the vascular wall and thus its aneurysmal dilation.

Etiologies

Direct Infection

In some cases the vascular wall is directly infected and most often an atherosclerotic plaque acts as the nidus for microbial infection. Consequently, such mycotic aneurysms usually occur in the context of atherosclerotic aneurysms, especially abdominal aortic aneurysms. In such cases the culprit organism is often Staphylococcus aureus, Streptococcus pyogenes, or Salmonella.

Embolic Infection

In rare cases, embolization of contaminated particles from vegetations of infective endocarditis can lodge in the vaso vasorum of large arteries and lead to infection of the vascular wall. When this does occur, such mycotic aneurysms frequently involve the cerebral arteries.