Bacterium
Moraxella catarrhalis
Oxidase-positive Gram-negative diplococcus
mor-ax-EL-uh kah-tar-AL-is
High-yield clue
Oxidase-positive diplococcus + respiratory tract comparison vocabulary.
Overview
A respiratory Gram-negative diplococcus used in coursework to avoid overcalling every Gram-negative diplococcus as Neisseria.
Classification
- Gram-negative
- Diplococcus
- Oxidase positive
Lab & identification clues
- Oxidase positive
- Diplococcus morphology
- Respiratory culture vocabulary
Associations
- Otitis media vocabulary
- Sinusitis vocabulary
- COPD exacerbation coursework association
Commonly confused with
- Neisseria meningitidis
- Neisseria gonorrhoeae
- Haemophilus influenzae
Frequently asked questions
What is Moraxella catarrhalis?
A respiratory Gram-negative diplococcus used in coursework to avoid overcalling every Gram-negative diplococcus as Neisseria.
What is the Gram stain of Moraxella catarrhalis?
Moraxella catarrhalis is Gram negative.
What are the lab clues for Moraxella catarrhalis?
Lab clues for Moraxella catarrhalis include Oxidase positive, Diplococcus morphology, and Respiratory culture vocabulary.
What is Moraxella catarrhalis commonly confused with?
Moraxella catarrhalis is commonly confused with Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae.
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.