35: MYCOTIC ANEURYSMAL DISEASE

PATIENT STORY

A 36-year-old man was admitted to the hospital with signs and symptoms of sepsis. He had a history of intravenous drug abuse as well as hepatitis B and C. He was discovered to have a left forearm abscess at an intravenous drug access site, as well as septic arthritis of the left hip with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia.

He underwent incision and drainage of the left hip and conservative management of the left forearm. A computed tomographic arteriogram (CTA) of the abdomen for abdominal pain showed inflammation around the distal abdominal aorta consistent with aortitis (Figure 35-1). Although his clinical course improved, his abdominal pain persisted and a repeat CTA 1 week later showed a large false aneurysm of the distal aorta (Figure 35-2).

Options were discussed and he underwent successful endovascular repair of the aorta (Figures 35-3 and 35-4) and was discharged eventually on long-term antibiotics.

EPIDEMIOLOGY

• Infectious aortitis represents a rare etiology of aortic aneurysm with one of the largest reviews revealing that 2.8% of 673 consecutive abdominal aortic aneurysm (AAA) patients presented with infectious aortitis as the etiology, including locations in the thoracic and abdominal aortas.¹

• The disease is significantly more devastating than traditional aneurysmal disease with a large proportion of patients with a mycotic aneurysm (19%-48%) presenting for the first time with rupture.^{1,2, and 3}

ETIOLOGY OR PATHOPHYSIOLOGY

• The term mycotic is actually a misnomer for infectious aortitis since most aortic infections are not secondary to a fungal pathogen. Many organisms have been implicated with S aureus being the most common.

• Others include Streptococcus pneumoniae, Listeria monocytogenes, Pseudomonas aeruginosa, Morganella morganii, Pasteurella multocida, and Salmonella species.^{4,5,6,7,8, and 9}

• Infections in native vessels are most commonly the result of seeding from a remote source or infections in an immunocompromised host. Infections also occur in previously placed prosthetic grafts, but this is a different disease entity and not the subject of this chapter.

DIAGNOSIS

Clinical Features

• The diagnosis of infectious aortitis is ...