HACEK endocarditis

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A HACEK organism is one of a set of slow-growing Gram negative bacteria that form a normal part of the human flora.

They are a rare cause of endocarditis in children,[1] but affect adults too.


The name is formed from their initials:[2]


All of these organisms are part of the normal oropharyngeal flora, which grow slowly, prefer a carbon dioxide–enriched atmosphere, and share an enhanced capacity to produce endocardial infections, especially in young children. Collectivelly they account for 5-10% of cases of infective endocarditis involving native valves and are the most common gram-negative cause of endocarditis among people who do not use IV drugs. They have been a frequent cause of culture-negative endocarditis. Culture negative refers to an inability to produce a colony on regular agar plates; this is because these bacteria are fastidious (requiring a specific nutrient).

In addition to valvular infections in the heart, they can also produce other infections such as bacteremia, abscess, peritonitis, otitis media, conjunctivitis, pneumonia, arthritis, osteomyelitis, and periodontal infections.


The treatment of choice for HACEK organisms in endocarditis is ceftriaxone, a third generation cephalosporin (penicillin-based) antibiotic. Ampicillin (a penicillin) and low-dose gentamicin (an aminoglycoside) is another therapeutic option.[5]


  1. ^ Feder HM, Roberts JC, Salazar JC, Leopold HB, Toro-Salazar O (June 2003). "HACEK endocarditis in infants and children: two cases and a literature review". Pediatr. Infect. Dis. J. 22 (6): 557–62. doi:10.1097/01.inf.0000069795.12338.cf. PMID 12799515. 
  2. ^ Morpeth S, Murdoch D, Cabell CH, et al. (December 2007). "Non-HACEK gram-negative bacillus endocarditis". Ann. Intern. Med. 147 (12): 829–35. PMID 18087053. 
  3. ^ "HACEK Group Infections: Overview - eMedicine Infectious Diseases". Retrieved 2009-03-17. 
  4. ^ Nørskov-Lauritsen N, Kilian M (September 2006). "Reclassification of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis as Aggregatibacter actinomycetemcomitans gen. nov., comb. nov., Aggregatibacter aphrophilus comb. nov. and Aggregatibacter segnis comb. nov., and emended description of Aggregatibacter aphrophilus to include V factor-dependent and V factor-independent isolates". Int. J. Syst. Evol. Microbiol. 56 (Pt 9): 2135–46. doi:10.1099/ijs.0.64207-0. PMID 16957111. 
  5. ^ [1], eMedicine, HACEK organism infection. June 2005.