Bacterium
Escherichia coli
Gram-negative lactose-fermenting rod
ESH-er-IK-ee-uh KOH-lye
High-yield clue
Gram-negative rod + lactose fermenter + oxidase negative is the core lab clue.
Overview
A common Gram-negative enteric rod used to teach lactose fermentation, GI pathotypes, urinary associations, and molecular-biology vocabulary.
Classification
- Gram-negative
- Rod
- Enterobacterales
- Facultative anaerobe
Lab & identification clues
- MacConkey lactose fermenter in many teaching examples
- Oxidase negative
- Indole positive is commonly taught
Associations
- Urinary tract study association
- GI pathotype vocabulary
- K1 capsule meningitis vocabulary
- Model organism in genetics
Commonly confused with
- Klebsiella pneumoniae
- Salmonella enterica
- Shigella species
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.