USMLE

Clostridium botulinum

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Bacteria - Gram Positive
  1. Staph aureus: Overview
  2. Staph aureus: Presentation
  3. Methicillin-Resistant Staph aureus (MRSA)
  4. Staph saprophyticus
  5. Strep pneumoniae: Overview
  6. Strep pneumoniae: Presentation
  7. Strep viridans
  8. Strep pyogenes: Overview
  9. Strep pyogenes: Presentation
  10. Strep agalactiae
  11. Strep bovis
  12. Enterococcus
  13. Bacillus anthracis
  14. Bacillus cereus
  15. Clostridium tetani
  16. Clostridium perfringens
  17. Clostridium botulinum
  18. Clostridium difficile
  19. Corynebacterium diphtheriae
  20. Listeria monocytogenes
  21. Nocardia
  22. Actinomyces

Clostridium botulinum 

  • Characteristics
    • Common to all bacteria in Clostridia family
    • Gram + rods
    • Obligate anaerobe
    • Spore-forming
  • Produces heat-labile exotoxin (botulinum)
    • Blocks acetylcholine release in presynaptic neurons
      • Cleaves SNARE proteins involved in neurotransmission
      • This neurotoxin inhibits acetylcholine release from the nerve terminals at neuromuscular junctions and causes a descending flaccid paralysis.
  • Exposure
    • ingestion of preformed toxin in home-canned food in adults
    • ingestion of spores in honey in infants
    • Local botox injections used to treat focal dystonia, achalasia, and muscle spasms
      • Also used for cosmetic reduction of facial wrinkles
  • Presentation: botulism
    • Descending flaccid paralysis in adults
      • Usually begins with cranial nerves and descends down to skeletal muscle
        • Contrast w Guillain-Barre syndrome - ascending paralysis 
      • Absent deep tendon reflexes
      • 4 D’s
        • Diplopia
        • Dysarthria
        • Dysphagia
        • Dyspnea
    • Floppy baby syndrome in infants
      • Constipation, weakness, lethargy, reduced feeding
  • Treatment
    • Treat with human botulinum immunoglobulin