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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 [3] 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 [2] - 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 [2] - signs & symptoms of endocarditis may be present * image [2] Laboratory: - complete blood count - blood cultures if endocarditis suspected [2] - microbiologic diagnosis of BCG 38% successful, based on - acid-fast bacilli smear - mycobacterial culture, or - PCR [3] Special laboratory: - 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 [3] - Surgical repair is often needed in cases of mycobacterial aortic aneurysms to prevent rupture [3]

General

vascular aneurysm

References

  1. DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 864
  2. Alibrahim BK, Wharmby G. (image) Ulnar-Artery Mycotic Aneurysm. N Engl J Med 2018; 378:e16. March 22, 2018 PMID: 29562157 Free full text http://www.nejm.org/doi/full/10.1056/NEJMicm1603196
  3. Rothaus C A Man with Delirium and Renal Insufficiency. NEJM Resident 360. Feb 17, 2021 https://resident360.nejm.org/clinical-pearls/a-man-with-delirium-and-renal-insufficiency