mycotic aneurysm; infected aneurysm

Etiology

• mycotic aneurysms may occur in association with endocarditis
• bacteria rather than fungi cause most mycotic aneurysms
  • Staphylococcus & Salmonella most common
  • prior to widespread use of antimicrobial therapy, syphilis was the most common cause
  • mycotic aneurysms may occur as a complication of < 6% of patients who receive intravesical instillation of BCG

Pathology

• localized dilatation of an artery (aneurysm) resulting from weakening of the vessel wall by growth of microorganisms (not necessarily fungi)
• may be associated with endocarditis
• if due to intravesical instillation of BCG
  • abdominal aorta more commonly involved than the thoracic aorta, but both aortic regions may be involved
  • iliac artery may also be involved
  • disseminated BCG infection is often paucibacillaryv[3]

Clinical manifestations

• aneurysm may be pulsatile & painful
• signs & symptoms of endocarditis may be present

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Laboratory

• complete blood count
• blood cultures if endocarditis suspected
• microbiologic diagnosis of BCG 38% successful, based on
  • acid-fast bacilli smear
  • mycobacterial culture, or
  • PCR

Diagnostic procedures

• echocardiogram if murmur or endocarditis suspected

Management

• if due to intravesical instillation of BCG
  • rifampin, isoniazid, & ethambutol +/- fluoroquinolone
  • BCG is inherently resistant to pyrazinamide
  • glucocorticoids often used
  • Surgical repair is often needed in cases of mycobacterial aortic aneurysms to prevent rupture

More general terms

• vascular aneurysm