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