Which pathogens cause culture-negative infective endocarditis (IE)?

Updated: Jan 03, 2019
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Many pathogens once considered to be fastidious are no longer classified as such (see above). Bartonella, Legionella, and C burnetii remain significant causes of culture-negative IE. These require special culture media or a prolonged incubation period for retrieval.

Serology for Chlamydia, Q fever (C burnetii), and Bartonella may be useful in culture-negative endocarditis. Serologic tests are often the most practical means for diagnosing valvular infection with fastidious organisms (eg, C burnetii and Chlamydia, Brucella, and Legionella species). Buffered charcoal and yeast agar are required for the isolation of Legionella. Brucella species require up to 6 weeks.

It appears that Tropheryma whippelii, which causes Whipple disease, is becoming a more common cause of culture-negative endocarditis. [64]

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