Bacterium
Eikenella corrodens
HACEK fight-bite Gram-negative rod
eye-kuh-NEL-uh kuh-ROH-denz
High-yield clue
Clenched-fist ('fight bite') human-bite wounds and HACEK-group endocarditis are the core clues; colonies characteristically pit or corrode the agar surface.
Overview
A slow-growing, capnophilic Gram-negative rod of the mouth and a member of the HACEK group. It is the classic teaching organism of human-bite ('fight bite') wounds and culture-negative-style endocarditis.
Classification
- Gram-negative
- Rod
- Facultative anaerobe / capnophilic
- HACEK group
- Oral flora
Lab & identification clues
- Pits / corrodes the agar surface
- Capnophilic (needs added CO2)
- Slow-growing HACEK member
- Gram-negative rod
Associations
- Human bite and clenched-fist wounds
- HACEK-group endocarditis
- Oral and upper respiratory flora
Commonly confused with
- Kingella kingae
- Pasteurella multocida (animal bites)
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.