Microbiology · 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
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 →
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)
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.
Related
Related conditions
← Back to the group: 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 (WHO, 2023); About Botulism (CDC, 2024); Botulism: MedlinePlus Medical Encyclopedia (MedlinePlus (NLM), 2024).
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Representative model, for educational purposes only.