Bacteria

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