• A 60-year-old postal worker presents to ED with the chief complaint of a dry cough for 5 days associated with fever, malaise, dyspnea on exertion, and pleuritic chest pain. There is no history of recent travel or contact with sick persons. Temperature is 102.5°F (39°C), blood pressure is 140/80mmHg, pulse is 100/min, respirations are 18/min, and oxygen saturation is 97%. Chest exam reveals an ill-looking man with bilateral rhonchi heard in the lung bases. Chest radiograph reveals a widened mediastinum and bilateral infiltrates. Blood cultures grew Gram-positive bacilli with a box-car appearance. 
  • Classification
    • bacteria
      • gram-positive bacilli
        • spore-forming
          • Bacillus
            • Bacillus anthracis
  • Pathogenesis
    • transmission
      • inhalation of spores (anthrax)
      • contact with infected animals (e.g., livestock or animal hide handling)
    • reservoir
      • animals
      • skin
      • soil
    • molecular biology 
      • polypeptide capsule is immunogenic and antiphagocytic
        • the only bacterium with a polypeptide capsule
        • contains D-glutamate 
      • anthrax toxin has 3 components
        • protective antigen
        • lethal factor
        • edema factor
          • mimics the activity of adenylate cyclase (cAMP)
          • responsible for edematous borders of black eschar
  • Anthrax
    • cutaenous anthrax
      • contact → black eschar (painless ulcer)
        • eschar is surrounded by edematous ring 
        • caused by lethal factor and edema factor
      • can progress to bacteremia and death
    • pulmonary anthrax
      • inhalation of spores → flu-like symptoms
      • rapid progression to fever, pulmonary hemorrhage, mediastinitis, shock, and death
        • near 100% mortality
      • sometimes called woolsorters' disease 
        • spores inhaled from contaminated sheep or goat skin/wool
    • GI anthrax
      • rare
  • Aerobic
  • Spore-forming rods
  • Serpentine or "medusa-head" appearance on microscopy
  • Large and "boxcar-like"
  • Diagnose with Gram stain and blood culture
  • Widened mediastinum on CXR
  •  Cutaneous
    • bubonic plague
    • lymphocutaneous tularaemia
    • primary syphillis
  • Pulmonary anthrax
    • pneumonia
    • influenza
  • Ciprofloxacin
  • Doxycycline
  • Toxoid vaccine to prevent
    • known as AVA (acellular vaccine adsorbed)
Prognosis, Prevention, and Complications
  • Prognosis
    • good if treated early with antibiotics
    • worse if pulmonary disease
  • Prevention
    • post-exposure prophylaxis
      • ciprofloxacin or doxycycline
      • vaccination with AVA
      • monoclonal antibodies if alternative therapies not tolerated
  • Complications
    • bacteraemia leading to sepsis
    • meninigitis

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