H Pylori Cards

Question 1

What are three common causes of duodenal ulcers?

Answer 1

H Pylori, NSAIDS, steroids

Question 2

What % of gastric cancers are associated with H Pylori?

Answer 2

70%; this makes H Pylori a WHO Type 1 definitive carcinogen

Question 3

What two types of cancer are associated with H. Pylori?

Answer 3

Gastric adenocarcinoma and gastric lymphoma (MALT lymphoma)

Question 4

Where and under what conditions does H Pylori grow?

Answer 4

H pylori grows in the antral and pyloric regions of the stomach; grows slowly in low O2

Question 5

What are the outcomes of H Pylori infection?

Answer 5

85% simple gastritis; 10-15% progress to peptic ulcer (usually duodenal); 1% progress to gastric cancer

Question 6

How is H Pylor infection usually acquired?

Answer 6

Within famillies or close contacts; often in childhood (90% by age 10)

Question 7

What is the environmental reservoir for H Pylori?

Answer 7

There is no environmental reservoir; strains follow human migration

Question 8

What are the protective benefits of H Pylori infection?

Answer 8

Possibly decreased esophageal carcinoma, childhood asthma, and TB

Question 9

How does H Pylori colonize the stomach?

Answer 9

H Pylori colonizes mucus (NOT the lumen), penetrates it via chemotaxis and acid excretion, then attaches to intercellular junctions of epithelial cells.

Question 10

Where does H Pylori grow and replicate?

Answer 10

Epithelial surface of gastric epithelium, attached at the intercellular junctions

Question 11

How does H Pylori protect against stomach acid exposure?

Answer 11

H Pylori secretes urease, which hydrolyzes urea into CO2 (released/absorbed) and NH3 which buffers the stomach’s acidic pH

Question 12

What is the histological findings of gastritis?

Answer 12

Inflammation in interstitial spaces between mucinous glands. 100% of people with H. Pylori infection develop histological gastritis.

Question 13

How does H Pylori evade the innate immune system? (4 ways)

Answer 13

1. LPS is 100x less bioactive, avoiding recognition TLR-4. 2. Molecular mimicry of blood group O-antigens. 3. Membrane-sheathed flagella protects from TLR-5 recognition. 4. Induces expansion of Tregs

Question 14

Which cells does H Pylori likely infect to cause gastric cancer?

Answer 14

It likely infects stem cells or other progenitor cells; intestinal lining is too short-lived to be cancer-inducing

Question 15

What are three modifiable risk factors for gastric cancer?

Answer 15

High salt diet, low iron, smoking

Question 16

What does the H Pylori virulence factor CagA do?

Answer 16

Disrupts cell polarity at intercellular junctions allowing H pylori to acquire nutrients; increased iron uptake by epithelium; inhibit apoptosis/stimulate proliferation; increase pro-inflammatory signals (which may lead to chronic inflammation/cancer)

Question 17

How does H Pylori CagA enter the cell?

Answer 17

A Type 4 Secretion System, or “molecular microsyringe,” injects a set of 30+ genes into the epithelium

Question 18

What are the two main H Pylori virulence factors?

Answer 18

CagA and VacA

Question 19

What does the H Pylori virulence factor VacA do?

Answer 19

VacA is a toxin that causes “vacuolation” or accumulation of vesicles within the epithelium. Role in pathogenesis remains unclear, but VacA is associated with increased risk of peptic ulcers and gastric cancer.

Question 20

How do duodenal ulcers modify the risk of gastric cancer?

Answer 20

Duodenal ulcers (with high acid secretion) actually lower the risk of gastric cancer (marked by low acid secretion/achlorhydria)

Question 21

What is the precursor condition to gastric cancer?

Answer 21

Atrophic gastritis (gastritis where gastric glands are lost and replaced by fibrous/intestinal epithelium)

Question 22

What is the currently recommended way to screen/treat H Pylori infection?

Answer 22

Screen adults that have symptoms of gastritis; treat adults with symptoms of an ulcer.

Question 23

Describe the shape and gram stain of H Pylori

Answer 23

Gram negative; spiral or curved shape

Question 24

Why would you treat an asymptomatic H Pylori infection?

Answer 24

Reduce the risk of gastric cancer in patients with first-degree relatives who have had gastric cancer