Review Note

Bacterial GIT Infections Causing Diarrhea

• Salmonella enterica serotype Enteritidis or Typhimurium.
• Shigella dysenteriae, Shigella flexneri, Shigella sonnei.
• Vibrio cholerae toxin-producing strains.
• Yersinia enterocolitica.
• Escherichia coli.
• Clostridium difficile.
• Campylobacter jejuni.
  
  
  
  

• General Symptoms:
  • Low-grade fever.
  • Nausea, vomiting.
  • Abdominal cramping, diarrhea.
  • Dehydration in severe diarrhea.
• Pathogen-Specific Symptoms:
  • V. cholerae: Profound rice-water diarrhea.
  • Shigella: Mucoid-bloody diarrhea (dysenteric stool).
  • Salmonella: Watery-bloody diarrhea + severe vomiting.
  • Yersinia: Watery-bloody diarrhea.
  • Campylobacter: Mucoid-bloody diarrhea.
  • C. difficile: Foul-smelling watery diarrhea (rarely bloody).
    
    
    
    

• Non-Infectious Diarrhea:
  • Food-borne: S. aureus intoxication, botulism.
  • Food poisoning: Histamine toxicity, chemical contaminants (e.g., lead, cadmium, insecticides).
  • Gastrointestinal: Celiac disease, lactose intolerance.
  • Malnutrition: Vitamin deficiency, colitis.
• Viral Infections:
  • E.g., norovirus, rotavirus, adenovirus.
• Parasitic Infections:
  • E.g., toxoplasmosis, amebiasis.
    
    
    
    

• Typically, clinical diagnosis.
• Stool sample may be taken in severe diarrhea, suspected C. difficile, or for epidemiological purposes:
  • Antigen testing with ELISA, PCR, bacterial culture.
    
    
    

• Mainly Symptomatic Treatment:
  • Rehydration – oral or intravenous in severe cases.
  • Rest.
  • Electrolyte replacement (e.g., electrolyte fluids or chips/salt crackers).
• Avoid Antidiarrheals:
  • May prolong symptoms and cause complications (e.g., bacteremia, toxic megacolon) in immunocompromised individuals.
• Indications for Antibiotic Therapy:
  • C. difficile diarrhea (asymptomatic carriers are not treated):
    • 1st line: Vancomycin.
  • Severe cases of other bacterial gastroenteritis or in immunocompromised patients:
    • E.g., doxycycline, fluoroquinolones, 3rd generation cephalosporins, macrolides.
• Hospitalization:
  • May be required in severe cases.