PetriKey

Bacterium

Streptococcus pneumoniae

Lancet diplococci and capsule clue

STREP-toh-KOK-us noo-MOH-nee-eye

Gram positivegram-positivediplococcialpha-hemolysiscapsulerespiratory

High-yield clue

Lancet-shaped diplococci + capsule + alpha-hemolysis is the study pattern.

Overview

A Gram-positive diplococcus frequently linked to capsule, alpha-hemolysis, optochin sensitivity, and respiratory-system educational cases.

Classification

  • Gram-positive
  • Diplococci
  • Alpha-hemolytic

Lab & identification clues

  • Optochin sensitivity is commonly taught
  • Bile solubility is a classic lab distinction
  • Capsule is high-yield

Associations

  • Pneumonia vocabulary
  • Meningitis vocabulary
  • Otitis/sinusitis teaching associations
  • Vaccine concept

Commonly confused with

  • Viridans streptococci
  • Neisseria meningitidis

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