Blood Culture Negative Endocarditis (BCNE)
Endocarditis without etiology following 3 sets of blood cultures with negative results after 5 days of incubation. Consult microbiologist and Infectious Diseases physician in all cases of BCNE.
- Cultures are negative for 2 major reasons:
previous administration of antibiotics - in these cases, viridans group streptococci most likely pathogen and should be treated empirically - see relevant Empiric Therapy recommendations (native valve, IVDU, prosthetic valve)
infection with highly fastidious bacteria (see below) or nonbacterial pathogens.
- If previous open heart surgery, consider Legionella spp or Mycobacterium spp. Consult microbiologist and Infectious Diseases.
- Also consider noninfectious causes of valvular vegetations:
anti-phospholipid antibody (APA) syndrome
neoplasia – atrial myxoma, marantic endocarditis, carcinoid
autoimmune – rheumatic carditis, systemic lupus erythematosus, polyarteritis nodosa, Behcet disease
post valvular surgery changes.
- For potential etiologic agents based on epidemiological risks; refer to Table 6 in Circulation 2015;132:1435-86.