HACEK GROUP;
Haemophilus species: parainfluenzae, aphrophilus, paraphrophilus
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae
These are group of fastidious, slow growing bacteria which normally reside in the oral cavity and are known to cause severe infections and endocarditis in particular.