H Pylori Flashcards
What is the shape and atmospheric requirement of Helicobacter pylori?
H. pylori is a slender, curved Gram-negative bacillus that is microaerophilic (requires low oxygen levels).
What enzyme allows H. pylori to survive in the stomach?
Urease, which converts urea to ammonia, neutralizing stomach acid around the bacteria.
What are the main diseases caused by H. pylori?
Chronic gastritis, peptic ulcers, gastric adenocarcinoma, and MALT lymphoma.
What are the primary transmission routes of H. pylori?
Fecal-oral and oral-oral routes.
What are the key virulence factors of H. pylori?
Urease, adhesins (BabA, SabA), CagA protein, VacA toxin, LPS, and flagella.
How does the CagA protein contribute to H. pylori pathogenesis?
It is injected into host cells via a type IV secretion system, altering signaling pathways, promoting inflammation, and increasing cancer risk.
What is the role of VacA toxin in H. pylori infection?
VacA causes vacuolation (cell damage), immune system evasion, and mucosal injury.
What diagnostic methods are used for H. pylori?
Non-invasive tests: Urea breath test, fecal antigen test, serology. Invasive tests: Histology, rapid urease test, culture.
What is the first-line treatment for H. pylori infection?
Triple therapy: Proton pump inhibitor (PPI), clarithromycin, and amoxicillin or metronidazole.
What is the alternative therapy for antibiotic-resistant H. pylori?
Quadruple therapy: PPI, bismuth subsalicylate, tetracycline, and metronidazole.
How does H. pylori evade the immune system?
It uses LPS that mimics host antigens, reducing immune detection, and secretes VacA toxin to impair immune cell function.
What symptoms are associated with H. pylori infection?
Epigastric pain, nausea, bloating, belching, and severe cases with black stools or vomiting blood.
How does H. pylori colonize the stomach?
It uses its flagella to penetrate gastric mucus, adheres via adhesins, and neutralizes acid with urease.
What is the role of the urease enzyme in H. pylori survival?
Urease breaks down urea into ammonia and CO2, neutralizing stomach acid around the bacterium.
What is the significance of the Cag pathogenicity island in H. pylori?
It encodes a type IV secretion system that injects CagA protein, which disrupts host cell processes and promotes inflammation.
