PetriKey

Bacterium

Shigella species

Nonmotile non-lactose fermenting rod

shih-GEL-uh

Gram negativebacteriagram-negativerodnonmotileenterictoxin

High-yield clue

Nonmotile non-lactose fermenter is the classic Salmonella contrast.

Overview

Enteric Gram-negative rods used in coursework to contrast nonmotility, non-lactose fermentation, and toxin-mediated vocabulary with Salmonella and E. coli.

Classification

  • Gram-negative
  • Rod
  • Enterobacterales

Lab & identification clues

  • Non-lactose fermenter
  • Nonmotile teaching clue
  • Shiga toxin vocabulary (classically S. dysenteriae type 1)

Associations

  • Dysentery vocabulary
  • Low infectious-dose concept
  • Food/water public-health framing

Commonly confused with

  • Salmonella enterica
  • E. coli pathotypes
  • Campylobacter jejuni

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.

OpenStax: Microbiology 2e organism classification foundationssourceNCBI Bookshelf: Medical Microbiology organism chapterssourceCDC: CDC disease and public-health topic pagessource