PetriKey

Disease

Community-acquired pneumonia

Lung infection acquired outside healthcare settings

noo-MOH-nee-uh

respiratorylungconsolidationtypical-atypicalcough

High-yield clue

Fever, productive cough, and focal consolidation point to Streptococcus pneumoniae as the classic typical cause.

Overview

An infection of lung parenchyma acquired in the community, studied through the split between typical (lobar) and atypical (walking) presentation patterns. It matters as one of the most common serious infections and a frequent exam scenario linking clinical picture to likely organism.

Classification

  • Lower respiratory syndrome
  • Typical vs atypical patterns
  • Lobar vs interstitial description
  • Community vs healthcare-associated framing

Lab & identification clues

  • Lobar consolidation and rust-colored sputum vocabulary
  • Atypical (walking) pneumonia with dry cough and diffuse infiltrate terms
  • Sputum Gram-stain and culture concept
  • Urinary antigen test vocabulary for pneumococcus and Legionella

Associations

  • Droplet and aspiration transmission framing
  • Atypical causes: Mycoplasma, Legionella, Chlamydophila vocabulary
  • At-risk groups: older adults, smokers, chronic lung disease
  • Pneumococcal vaccine public-health framing

Commonly confused with

  • Tuberculosis
  • Acute bronchitis

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