[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/) › Clostridium botulinum

[Microbiology](https://durgical.com/en/microbiology/) · [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

# Clostridium botulinum

- Bacterium
- Gram-positive
- Exam priority: medium

A soil bacterium whose toxin, the most potent known, causes a flaccid paralysis that can stop breathing.

Updated 2026-11-01

Also called: botulism bacillus

## Key points

- Blocks acetylcholine release: descending flaccid paralysis.
- Starts with the cranial nerves: diplopia, ptosis, dysphagia.
- Infant: spores in honey.
- Adult: preformed toxin in home-canned food.
- Treatment: antitoxin and ventilation.

## At a glance

**Gram**
Gram-positive

**Shape**
Rod with a subterminal spore

**Oxygen**
Obligate anaerobe

**Family**
Clostridiaceae

**Stain**
Gram positive; spore former

## Morphology

- Gram-positive rod
- Heat-resistant spores
- Makes toxin in oxygen-poor conditions

## Transmission

- Improperly home-canned or fermented food with preformed toxin
- Infants who swallow spores (honey) that germinate in the gut
- Spores in wounds (wound botulism)
- Not spread from person to person

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Botulinum toxin: cleaves SNARE proteins in the presynaptic terminal
- Stops acetylcholine release at the neuromuscular junction and autonomic synapses
- Result: descending flaccid paralysis

## Diseases it causes

- Foodborne, infant, wound and iatrogenic botulism [Botulism →](https://durgical.com/en/conditions/botulism/)

## Clinical picture

- Blurred vision, diplopia, ptosis, slurred speech and trouble swallowing at onset
- Descending, symmetric flaccid paralysis
- No fever and a clear mind
- Floppy infant: constipation, weak cry, poor feeding

## Diagnosis

- Clinical diagnosis; treatment does not wait for the lab
- Toxin detection in serum, stool or food
- Stool culture in infant botulism

## Treatment

Botulinum antitoxin as early as possible (and for infants, human botulism immune globulin), with ventilatory support that can last weeks. Antibiotics are not needed except in wound botulism.

Drug class only; doses and regimens are set by the clinician from the current guideline.

## Prevention

- Correct home canning and preserving techniques
- No honey for children under one year
- Boiling suspect home-canned food destroys the toxin (not the spores)

## Memory aid

Botulism lowers the curtain: it starts at the eyes and mouth and drops down to the breathing muscles.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the mechanism of botulinum toxin?

It cleaves SNARE proteins and stops acetylcholine release at the neuromuscular junction: flaccid paralysis.

## Why is honey not given to children under one year?

It may carry C. botulinum spores that germinate in the immature gut and make toxin.

## How does the paralysis of botulism differ from Guillain-Barré syndrome?

Botulism descends and starts with the cranial nerves; Guillain-Barré usually ascends.

## What is the main treatment of botulism?

Early antitoxin and respiratory support; antibiotics are not used except in wound botulism.

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## Related

- [Clostridium tetani](https://durgical.com/en/microbiology/clostridium-tetani/)
- [Clostridium perfringens](https://durgical.com/en/microbiology/clostridium-perfringens/)

## Related conditions

- [Botulism](https://durgical.com/en/conditions/botulism/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Botulism](https://www.who.int/news-room/fact-sheets/detail/botulism) (WHO, 2023); [About Botulism](https://www.cdc.gov/botulism/about/index.html) (CDC, 2024); [Botulism: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000598.htm) (MedlinePlus (NLM), 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/clostridium-botulinum/