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PetriKey

Bacterium

Legionella pneumophila

Water-associated intracellular rod

lee-juh-NEL-uh noo-MOH-fih-luh

Gram negativebacteriagram-negativerodwaterintracellularrespiratory

High-yield clue

Water system exposure vocabulary + atypical pneumonia teaching clue.

Overview

A water-associated bacterium used to teach atypical pneumonia vocabulary, intracellular survival concepts, and outbreak investigation framing.

Classification

  • Gram-negative
  • Rod
  • Intracellular survival concept

Lab & identification clues

  • Poor Gram-stain visibility in teaching examples
  • Urinary antigen vocabulary
  • Buffered charcoal yeast extract is a term to recognize, not a protocol

Associations

  • Atypical pneumonia vocabulary
  • Cooling-tower/outbreak framing
  • Intracellular pathogen concept

Commonly confused with

  • Mycoplasma pneumoniae
  • Streptococcus pneumoniae

Frequently asked questions

What is Legionella pneumophila?

A water-associated bacterium used to teach atypical pneumonia vocabulary, intracellular survival concepts, and outbreak investigation framing.

What is the Gram stain of Legionella pneumophila?

Legionella pneumophila is Gram negative.

What are the lab clues for Legionella pneumophila?

Lab clues for Legionella pneumophila include Poor Gram-stain visibility in teaching examples; Urinary antigen vocabulary; Buffered charcoal yeast extract is a term to recognize, not a protocol.

What is Legionella pneumophila commonly confused with?

Legionella pneumophila is commonly confused with Mycoplasma pneumoniae and Streptococcus pneumoniae.

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 foundations - sourceNCBI Bookshelf: Medical Microbiology organism chapters - sourceCDC: CDC disease and public-health topic pages - source