Medicine & USMLE

Yersinia enterocolitica

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Bacteria - Gram Negative
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Yersinia enterocolitica 

  • Characteristics
    • Gram negative coccobacilli
    • Requires iron as an essential growth factor
      • Most strains lack efficient iron-uptake mechanisms
    • Grows in cold temperatures (refrigeration)
    • Many virulent strains may be calcium-dependent
  • Virulence factors
    • Enterotoxin
      • Activates guanylate cyclase, increasing cGMP
        • Intracellular increase in cGMP leads to watery diarrhea
  • Transmission
    • Oral ingestion of bacteria
      • pet feces
      • undercooked pork
      • may also appear in contaminated milk
  • Presentation
    • Watery diarrhea 
      • Invades GI mucosa and releases enterotoxin, causing watery diarrhea
    • Pseudoappendicitis 
      • Right lower abdominal pain due to growth and inflammation in mesenteric lymph nodes
      • appendix appears normal on CT 
  • Treatment
    • Antibiotics are not indicated for uncomplicated diarrhea
      • Supportive care (hydration) is standard of care
    • Severe cases may warrant antibiotics
      • Fluoroquinolones or TMP-SMX
      • Cephalosporins and gentamicin also used for sepsis