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Helicobacter pylori

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Helicobacter pylori 

  • Characteristics
    • Gram negative rod
      • First test in algorithm, narrows scope of bacteria
    • Curved/spiral-shaped
    • Oxidase +
      • All gram negative curved rods are oxidase positive 
    • Urease +
      • Produces ammonia, creating alkaline environment
      • Helps H pylori survive in acidic gastric mucosa
    • Catalase +
    • Has flagella (motile)
  • Pathogenesis
    • Commonly colonizes antrum of the stomach 
      • Most often the prepyloric area (less acidic)
      • Destroys somatostatin-producing delta cells in the antrum, contributing to increased acid production
    • Increased acid production and local inflammatory reaction to bacteria causes ulcer formation
  • Presentation
    • Gastritis
      • Early manifestation of H pylori infection
      • Presents with dyspepsia, bloating, belching, and epigastric pain
      • Over time, results in potential complications
        • Atrophic chronic gastritis
        • Gastric cancer (adenocarcinoma)
        • Gastric lymphoma (MALTomas)
    • Gastric or Duodenal ulcers 
      • Increased acid production causes destruction of mucus layer, compounded with local inflammatory reaction to bacteria
      • H. pylori is the most common cause of peptic ulcers, especially in the duodenum
  • Diagnosis
    • Urea breath test
    • Fecal antigen test
    • Endoscopy with gastric biopsy 
      • H. pylori may be seen under the microscope
      • Urease may be detected from biopsy of gastric mucosa
  • Treatment
    • Triple therapy
      • Amoxicillin 
        • metronidazole is used if allergic to penicillins
      • Clarithromycin
      • Proton pump inhibitor (omeprazole)
    • Bismuth-based quadruple therapy if concerned about macrolide resistance 
      • Bismuth subcitrate, PPI, metronidazole, tetracycline