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