PetriKey

Bacterium

Neisseria meningitidis

Gram-negative diplococci

nye-SEER-ee-uh meh-nin-JIT-ih-dis

Gram negativegram-negativediplococcioxidasecapsulemeningitis

High-yield clue

Gram-negative diplococci + oxidase positive + capsule is the recognition pattern.

Overview

A Gram-negative diplococcus linked to oxidase positivity, capsule concepts, and meningitis/outbreak vocabulary in educational cases.

Classification

  • Gram-negative
  • Diplococci
  • Oxidase positive

Lab & identification clues

  • Oxidase positive
  • Chocolate agar vocabulary
  • Capsule is high-yield

Associations

  • Meningitis vocabulary
  • Petechial rash clue in educational cases
  • Vaccine/public-health concepts

Commonly confused with

  • Neisseria gonorrhoeae
  • 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