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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

Frequently asked questions

What is Neisseria meningitidis?

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

What is the Gram stain of Neisseria meningitidis?

Neisseria meningitidis is Gram negative.

What are the lab clues for Neisseria meningitidis?

Lab clues for Neisseria meningitidis include Oxidase positive, Chocolate agar vocabulary, and Capsule is high-yield.

What is Neisseria meningitidis commonly confused with?

Neisseria meningitidis is commonly confused with Neisseria gonorrhoeae 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