H. Pylori Flashcards
(29 cards)
What type of bacteria is it?
G -, spiral shaped with flagellum
The unique properties of H. pylori allow it to do what?
Colonize gastric epi in an acidic environment
Where does it grow?
In mucus layer that coats the inside of the stomach
H. pylori is the most frequent cause of
chronic gastritis
Infection can varialy lead to severe gastroduodenal conditions, including
- Gastric and duodenal peptic ulcer disease
- Gastric cancer
- Gastric mucosa- associated lymphoid tissue lymphoma (MALT)
How does it spread?
Person to person through oral contact with saliva
Chronic infection causes
long lasting inflammation and non-atrophic gastritis in most people
Neutrophils, lymphocytes, plasma cells, and macrophages within the mucosal
layer cause
epithelial cell degeneration and injury
Where is gastritis usually more severe?
In the antrum of the stomach
The long term inflammation can lead to
atrophic gastritis (thinning of stomach lining)
How are peptic ulcers characterized?
By denuded mucosa with the defect extending into the submucosa or muscularis mucosa
Symptoms
- Dull or burning stomach pain
- Burping, bloating, indigestion
- Loss of appetite, weight loss
- Nausea, vomiting
- Dark stools
- Perforation is common
What are oral manifestations?
- Oral sores that can lead to bad breath
- Tongue discoloration from meds
- Lowered salivary pH (decreased buffering capacity and flow rate)
- Cellulitis, infections, cancer, spread of contagious disorders
Describe the virulence factor of urease
Essential for colonization
Cleaving urea into ammonia and CO2 which allows bacteria to survive in stomach
Describe motility
Driven by flagella can enter and replicate in mucus layer
Movement is directional in the gastric mucus, with orientation through pH and bicarbonate gradients
Describe adhesion
Can adhere by attaching to surface molecuels anchored on its outer membrane. Adhesion enables it to colonize despite epithelial shedding, mucus turnover and physical forces
Describe LPS
PAMP molecule binds to TLR and activates inflammation
What is VacA?
Protein toxin that induced the formation of large intracellular vacuoles and inhibition of T cell and B cell proliferation.
Causes downregulation of immune responses to infection and promotes host tolerance
Cytotoxin associated gene A induces
inflammation, disrupts tight junctions and is carcinogenic
The most well-characterized H. pylori virulence determinant is the
cag pathogenicity island
What type of secretion system do the encoded proteins build?
Type IV
CagA (cytotoxin-associated gene A) is
carcinogenic protein delivered into gastric epithelial cells
What are extra-gastric diseases that can be caused by H. pylori infection?
- Iron def anemia
- Vit B12 def
- Idiopathic thrombocytopenic purpura from H. pylori antigen mimicry-induce autoimmunity
An inverse association between H. pylori infection and the risk of
- Asthma and allergy in children
- GERD
- Barretts esophagus
- Esophageal adenocarcinoma
