Endocarditis due to Gram-negative organisms is infrequent. Gram-negative organisms are responsible for <4% of cases worldwide. Infective endocarditis caused by Gram-negative bacteria is a severe disease and presents a high rate of complications and high mortality. It often has a nosocomial origin, and it is caused by resistant organisms.
HACEK organisms include:
- Haemophilus species
- Actinobacillus actinomycetemcomitans
- Cardiobacterium hominis
- Eikenella corrodens
- Kingella kingae
These organisms are commonly found in the normal oral flora. Although they are gram-negative, these organisms require a rich medium, such as chocolate agar, for growth. From there comes the name of fastidious organisms.
And Non-HACEK Gram-Negative Endocarditis:
- Pseudomonas aeruginosa
- Escherichia coli
- Morpeth S, et al.; International Collaboration on Endocarditis Prospective Cohort Study (ICE-PCS) Investigators. Non-HACEK gram-negative bacillus endocarditis. Ann Intern Med. 2007 Dec 18;147(12):829-35.
- Sharara SL, Tayyar R, Kanafani ZA, Kanj SS. HACEK endocarditis: a review. Expert Rev Anti Infect Ther. 2016 Jun;14(6):539-45. doi:10.1080/14787210.2016.1184085.
- Durante-Mangoni E, Tripodi MF, Albisinni R, Utili R. Management of Gram-negative and fungal endocarditis. Int J Antimicrob Agents. 2010 Dec;36 Suppl 2:S40-5. doi: 10.1016/j.ijantimicag.2010.11.012.
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