Shigellosis

• Pathogens: Shigella dysenteriae, Shigella flexneri, Shigella sonnei
  • Gram-negative rods
  • Produce Shiga toxin (enterotoxin) and endotoxin
  • Invade M cells via pinocytosis and travel from cell to cell via actin filaments (no hematogenous spread)

Cholera

• Pathogen: Vibrio cholerae
• Infectivity
  • Acid-labile (grows well in an alkaline medium)
  • High infective dose required (over 10⁸ pathogens)
  • Gastric acid provides a natural barrier against V. cholerae infection
    • Patients on long PPI are more easily to get infected