3.21 H. Pylori

Microbiology review for the USMLE Step 1 exam

• Helicobacter Pylori (H. Pylori) is a gram-negative, comma-shaped bacteria that causes chronic gastritis
• Estimated that 50% of people worldwide are infected with H. Pylori; higher in developing countries, lower in developed countries
• More common in populations with lower socioeconomic status and in crowded conditions with poor hygiene
• Spread through oral-oral or fecal-oral routes
• Colonizes the antrum of the stomach
• Produces urease that converts urea into carbon dioxide and ammonia, helping it survive in the acidic environment of the stomach
• Secretes toxins that cause inflammation of the gastric epithelium and lead to gastritis and ulcer formation
• Most people with H. Pylori never have symptoms, but some may present with dyspepsia, abdominal pain, nausea, vomiting, gastritis, or peptic ulcer disease
• Duodenal ulcers often associated with H. Pylori or heavy NSAID use
• Diagnosis can be made through urea breath test, stool antigen test, or endoscopy with gastric biopsy
• Treated with a triple drug regimen of a proton pump inhibitor, clarithromycin, and amoxicillin or metronidazole (triple therapy)
  • PCAM