- Clinical science
Botulism is a life-threatening condition of neuroparalysis that is caused by a potent neurotoxin produced by the spore-forming bacteria Clostridium botulinum. Botulinum toxin blocks the release of acetylcholine from motor end plates into the synaptic cleft, irreversibly inhibiting neurotransmission. There are three main types of botulism: foodborne botulism, infant botulism, and wound botulism. Foodborne botulism results from the ingestion of a food product already contaminated with botulinum toxin (typically home-canned foods). Infant botulism represents the majority of cases and is caused by the ingestion of spores (commonly from honey or soil), which then germinate and produce neurotoxins within the intestinal tract. In wound botulism, which typically occurs in IV drug users, Clostridium botulinum spores germinate in contaminated wounds. All three types present with neuroparalysis, while foodborne and infant botulism are sometimes also associated with gastrointestinal symptoms (e.g., discomfort, nausea, constipation). Clinical suspicion of botulism may be confirmed by quickly identifying the toxin in bodily fluids (e.g., serum, vomit, gastric acid, stool) and/or food. Foodborne botulism is best treated with an antitoxin and medically-induced bowel emptying. Treatment of infant botulism consists of the administration of botulism immune globulin. Wound botulism requires surgical debridement in addition to antitoxin administration.
- Gram-positive rod
- Obligate anaerobe
- Produces heat-labile neurotoxin
- Botulinum toxin
- Descending paralysis
- Autonomic nervous system: xerostomia
- Infants may present with ptosis, floppy movements, general weakness, and poor feeding (weak sucking)
- Gastrointestinal symptoms: gastrointestinal discomfort, nausea, and vomiting, later followed by constipation
- Rapidly identify botulinum toxin in samples from serum, vomit, gastric acid, stool, or suspicious foods “
- Secure airways
- See the corresponding section for specific treatment measures.
Ingestion of the botulinum toxin
- The anaerobic spores survive in canned foods (e.g., home-canned vegetables) and packed meat despite vacuum sealing.
- Germination of the spores produces dangerous toxins (botulinum toxins = enterotoxins A-F) and gas → bulging cans
- Ingestion of the botulinum toxin
- Incubation period: 12–36 hours
- Administer (horse-derived) heptavalent botulism antitoxin
- Eradication of toxin through bowel emptying (induced by medication)
- Sterilize food through autoclaving.
- Food should be boiled twice before being canned to kill spores that may have germinated after the first round of boiling.
Ingestion of spores
- Spores may be present in honey or contaminated soils.
- Germination of the spores in intestinal tract → synthesis of botulinum toxin
- Ingestion of spores
- Incubation period: days to 4 weeks
- Administer IV human botulism immune globulin (BIG-IV)
- Prevention: avoid honey during the first year of life
- Germinating spores in contaminated wounds (common among IV drug users)
- Incubation period: 10 days (ranges from 4–14 days)
- Administration of botulism antitoxin
- Surgical debridement
- Antibiotics are only used to treat secondary bacterial infections.
- Guillain-Barré syndrome: associated with ascending paralysis
The differential diagnoses listed here are not exhaustive.