Group of gram-negative fastidious rods- Aggregatibacter aphrophilus (formerly Haemophilus aphrophilus)- Aggregatibacter actinomcetemcomitans- Cardiobacterium hominis- Eikenella corrodens- Kingella kingae

- HACEK organisms usually responsible for 5-10% of infective endocarditis (usually subacute)

- Most common cause of gram-negative endocarditis in non-IV drug users

- All part of normal oral flora

Treatment: third-generation cephaosporin or fluoroquinolone