PetriKey

Bacterium

Mycoplasma pneumoniae

No cell wall atypical bacterium

my-koh-PLAZ-muh noo-MOH-nee-eye

bacteriaatypicalno-cell-wallrespiratorysterol

High-yield clue

No cell wall + atypical respiratory vocabulary + cold agglutinin teaching clue.

Overview

An atypical bacterium used to teach the absence of a cell wall, pleomorphic morphology, and walking-pneumonia coursework vocabulary.

Classification

  • Atypical bacterium
  • No peptidoglycan cell wall
  • Pleomorphic

Lab & identification clues

  • Gram stain is not useful as a primary anchor
  • NAAT/serology vocabulary
  • Fried-egg colony term appears in older teaching

Associations

  • Atypical pneumonia vocabulary
  • Cold agglutinin concept
  • Macrolide-resistance discussion

Commonly confused with

  • Legionella pneumophila
  • Chlamydia pneumoniae
  • Streptococcus pneumoniae

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