Question | Answer |
What are the HACEK organisms? | Haemophilus aphrophilus. Actinobacillus actinomycetemcomitans. Cardiobacterium hominis. Eikenella corrodens. Kingella species. |
Which organism is the most prevalent in causing endocarditis and what are the biochemical chemical reactions? | Haemophilus aphropilus. Catalase, urea, and indole = negative. Ferments lactose. |
What are the two species of Kingella and which is important in children? | 1) Kingella denitrificans
2) Kingella kingae, most important in children <5, causing bone and joint infections and bacteremia. |
What is A. actinomycetemcomitans associated with and what are some ways to identify it? | It is associated with Actinomycotic lesions, normally of the jaw, destructive periodontitis, and abscesses within the thoracic cavity.
It is a coccobacillary GNR, with Morse Code appearance. Star like colony morphology but does NOT grow on MAC. |
Which organism forms rosette-like arrangements on gram stain and what are the biochemical reactions? | Cardiobacterium hominis. It is oxidase + and spot indole +. It is also urea, catalase, nitrate, gel, and esculin negtaive. It will NOT grow on MAC. |
How is an Eikenella corrodens infection acquired? | Causes bacteremia and endocarditis often seen in IV drug users or from extensive dental work. Also human bites or "clenched fist wounds." |
How is Eikenella corrodens identified? | Gram stain = GNR
Media = grows well on BAP or CHOC but NOT MAC. some isolates may "pit" or corrode the agar.
Biochemical = Oxidase, lysine, ornithine, and nitrate = postive. Catalase negative. Non-glucose utilizer. |
What do all the HACEK organisms have in common? | They are GNRs, that grow in increased CO2. They are the major cause of endocarditis while also considered as normal oral flora that are opportunists. |