Infectious Aortitis

Infection of the aorta usually results from septic embolization to the vasa vasorum, hematogenous seeding of an existing aneurysm, or extension from a contiguous site of infection. The diagnosis should be considered in patients, often men over the age of 50 years with atherosclerosis, who present with fever, abdominal pain, palpable abdominal mass, and leukocytosis, with or without positive blood cultures. In the pre-antibiotic area, infectious aortitis was largely a complication of infective endocarditis, and was usually caused by group A streptococci, Streptococcus pneumoniae, or Haemophilus influenzae. Now a diverse array of bacteria and fungi has been associated, most commonly Salmonella species, which comprise nearly one third of the abdominal aortic infections and Staphylococcus aureus. Computed tomography is the most useful imaging modality. Medical treatment alone carries a high mortality, whereas the mortality with surgery combined with antimicrobial treatment is lower. Empiric antibiotics effective against S. aureus and gram-negative rods, such as Salmonella, should be initiated in cases identified before microbiologic diagnosis. Surgical debridement and revascularization should be completed early because delay may lead to aneurysm rupture, which increases mortality. The intent of surgery is to 1) control hemorrhage, if the aneurysm has ruptured; 2) confirm the diagnosis; 3) control sepsis; and 4) reconstruct the arterial vasculature. The patient should remain on parenteral or oral antibiotics for at least 6 weeks, perhaps longer, to assure full eradication of the pathogen and prevent recurrent infection. Close medical follow-up is indicated and includes serial blood cultures and computed tomography scans.