Clostridium botulinum

Snapshot

• A 40-year-old man presents to the emergency room for blurry vision. He reports that the blurry and double vision started this morning along with nausea and vomiting. He also reports feeling weak in his arms. Upon further questioning, he recently ate a can of beans from his aunt in Alaska, where they run their own food storage business. On physical exam, there is bilateral ptosis and facial weakness. There is also bilateral upper arm weakness with absent deep tendon reflexes. His mental status is intact. His physician immediately administers antitoxin treatment for the disease.

Introduction

• Classification 
  • Clostridium botulinum 
    • anaerobic gram + rod 
    • produces botulinum exotoxin
  • transmission
    • ingestion of spore
    • ingestion of preformed toxins
    • direct wound contamination
    • inhalation (rare)
• Epidemiology
  • demographics
    • adults
    • infants
  • risk factors
    • ingestion of old or expired bottles or cans of food or honey 
    • wound contamination
    • intravenous drug use
• Pathogenesis  
  • forms spores
    • highly resistant to heat and chemicals
    • ingestion of spores causes infantile botulism
      • toxin is then produced in infant’s gut
      • most commonly from ingestion of contaminated honey
  • forms heat-labile exotoxin
    • irreversibly inhibits acetylcholine release at the neuromuscular junction by cleaving SNARE proteins
    • ingestion of exotoxin causes adult botulism
  • botulinum toxin is absorbed into bloodstream from mucosal surface
  • botox injections are used for
    • focal dystonia
    • achalasia
    • muscle spasms
    • cosmetic appearance
• Associated conditions
  • foodborne botulism
  • wound botulism
• inhalation botulism

Presentation

• Symptoms
  • gastrointestinal upset in foodborne botulism
  • infantile botulism
    • poor feeding and diminished suck
• Physical exam 
  • cranial nerve palsies
    • blurry vision
    • ptosis
    • facial weakness
    • drooping eyelids
    • 4 D’s
      • Diplopia
      • Dysarthria
      • Dysphagia
      • Dyspnea
  • autonomic nervous system dysfunction
    • dry mouth
    • postural hypotension
  • descending symmetric muscle weakness and flaccid paralysis
• absent deep tendon reflexes

Studies

• Labs
  • typically normal
  • toxin may be detected from serum, stool, or wound
    • process takes a few days, so this is only used as confirmatory testing
    • for infant botulism, stool toxin tests are prefered since serum toxin assays are often negative 
• Making the diagnosis
• most cases are clinically diagnosed

Differential

• Guillain-Barré syndrome
  • distinguishing factor
    • typically an ascending paralysis
• Bacterial meningitis in neonates
  • distinguishing factor
• besides poor feeding or diminished suck, patients may have bulging fontanelle, nuchal rigidity, and abnormal labs

Treatment

• Management approach
  • immediate treatment with antitoxin
• Medical
  • equine-derived heptavalent antitoxin
    • indication
      • patients > 1 years of age
  • bivalent human-derived antitoxin (BabyBIG)
    • indication
• patients < 1 years of age

Complications

• Respiratory paralysis
• Permanent paralysis