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PetriKey

Bacterium

Clostridium tetani

Terminal-spore tetanus rod

klos-TRID-ee-um TET-uh-nye

Gram positivegram-positiverodanaerobespore-formingtoxinneurotoxin

High-yield clue

Terminal spores give a tennis-racket or drumstick shape, and tetanospasmin blocks release of inhibitory GABA and glycine to cause spastic paralysis.

Overview

An obligate anaerobic, spore-forming Gram-positive rod that produces the neurotoxin tetanospasmin. It is the standard teaching organism for spastic (rigid) paralysis after wound contamination.

Classification

  • Gram-positive
  • Rod
  • Obligate anaerobe
  • Spore-forming (terminal endospore)

Lab & identification clues

  • Terminal spore 'tennis-racket' appearance
  • Obligate anaerobe
  • Motile study distinction
  • Toxin-mediated disease vocabulary

Associations

  • Puncture wound / soil contamination
  • Lockjaw (trismus) and risus sardonicus presentation vocabulary
  • Spastic paralysis and opisthotonus

Commonly confused with

  • Clostridium botulinum
  • Clostridium perfringens

Frequently asked questions

What is Clostridium tetani?

An obligate anaerobic, spore-forming Gram-positive rod that produces the neurotoxin tetanospasmin. It is the standard teaching organism for spastic (rigid) paralysis after wound contamination.

What is the Gram stain of Clostridium tetani?

Clostridium tetani is Gram positive.

What are the lab clues for Clostridium tetani?

Lab clues for Clostridium tetani include Terminal spore 'tennis-racket' appearance, Obligate anaerobe, Motile study distinction, and Toxin-mediated disease vocabulary.

What is Clostridium tetani commonly confused with?

Clostridium tetani is commonly confused with Clostridium botulinum and Clostridium perfringens.

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