HACEK organisms
Chapter: 9b
An acronym for a group of fastidious Gram-negative organisms that are sometimes capable of causing endocarditis, and that may not grow in the standard amount of time that blood cultures are incubated (5 days). If you suspect that a patient has endocarditis due to a fastidious organism, you must request that the lab keep the blood culture for at least 2 weeks. Enriched media is also required for growth upon subculture, although they will grow in the blood culture broth. The HACEK organisms are: Hemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominus, Eikenella corrodens, and Kingella spp.