PetriKey

Lab method

Oxidase test

Cytochrome c oxidase clue

OK-sih-days

Gram negativelaboxidasegram-negativenonfermenter

High-yield clue

Pseudomonas and Neisseria are oxidase-positive teaching anchors; many Enterobacterales are oxidase negative.

Overview

A biochemical test concept that helps separate certain Gram-negative organisms by cytochrome c oxidase activity.

Classification

  • Biochemical test
  • Respiratory enzyme concept

Lab & identification clues

  • Color-change vocabulary
  • Gram-negative flowchart branch

Associations

  • Pseudomonas
  • Neisseria
  • Enterobacterales contrast

Commonly confused with

  • Catalase test
  • Coagulase test

Your notes

Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.

OpenStax: Microbiology 2e staining, media, and biochemical-test foundationssourceNCBI Bookshelf: Medical Microbiology diagnostic concept foundationssource