What are the causes of IV drug abuse (IVDA) infective endocarditis (IE)?

Updated: Jan 03, 2019
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Diagnosis of endocarditis in IV drug users can be difficult and requires a high index of suspicion. Two thirds of patients have no previous history of heart disease or murmur on admission. A murmur may be absent in those with tricuspid disease, owing to the relatively small pressure gradient across this valve. Pulmonary manifestations may be prominent in patients with tricuspid infection: one third have pleuritic chest pain, and three quarters demonstrate chest radiographic abnormalities.

S aureus is the most common (< 50% of cases) etiologic organism in patients with IVDA IE. MRSA accounts for an increasing portion of S aureus infections and has been associated with previous hospitalizations, long-term addiction, and nonprescribed antibiotic use. Groups A, C, and G streptococci and enterococci are also recovered from patients with IVDA IE.

Currently, gram-negative organisms are involved infrequently. P aeruginosa [19] and the HACEK family are the most common examples.

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