The<unk>  are a group of fastidious Gram-negative bacteria that are an unusual cause of infective endocarditis, which is an inflammation of the heart due to bacterial infection.<unk>  is an abbreviation of the initials of the genera of this group of bacteria: Haemophilus, Aggregatibacter (previously Actinobacillus), Cardiobacterium, Eikenella, Kingella. The<unk>  are a normal part of the human microbiota, living in the oral-pharyngeal region. The bacteria were originally grouped because they were thought to be a significant cause of infective endocarditis, but recent research has shown that they are rare and only responsible for 1.4–3.0% of all cases of this disease.
HACEK organisms
Enteric bacteria 
Coliform bacteria
Streptococcus
Enterococcus
Haemoconia
Lactobacillus
Nontuberculous mycobacteria