Although not performed that often, the following tests are useful in separating E. corrodens from other closely related members of the HACEK group:
- KIA showing an alk/alk reaction; Glucose fermentation (-); Reduction of nitrates to nitrites (+); Production of indole (-); Ornithine decarboxylase (+)
- The positive nitrate reduction reaction eliminates Cardiobacterium hominis, Kingella kingae and other Kingella species.
- The positive ornithine decarboxylase reaction eliminates Kingella denitrificans (which also denitrifies nitrate to nitrogen gas, a reaction negative for E. corrodens).
- Eikenella corrodens is asaccharolytic, whereas most other closely related species produce acid from one or more carbohydrates.