Background
The acronym HACEK refers to a group of fastidious gram-negative coccobacillary organisms. HACEK stands for Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species. The HACEK group accounts for approximately 5%-10% of community-acquired native-valve endocarditis cases in patients who do not use intravenous drugs.
HACEK microorganisms grow slowly in standard blood culture media, and recovery may require prolonged incubation.
HACEK organisms are typically oropharyngeal commensals and have long been recognized as a cause of infective endocarditis (IE).
Eikenella and Cardiobacterium species have been recovered from the gastrointestinal tract and female genital tract.
In addition to infective endocarditis, these organisms have also known to cause wound infections (particularly of bite wounds), soft-tissue abscess, brain abscess, endophthalmitis, parotitis, periodontitis, empyema and bacteremia without endocarditis, and osteomyelitis. In addition, rare cases of endometritis and urinary tract infection have been identified. Invasive infections commonly occur in the setting of trauma, underlying structural heart disease, malignancy, and other immunocompromised states.