H.Pylori

Question 1

How is H.Pylori transmitted

Answer 1

Through consumption of contaminated food and water
from infected parent to child (mother or father)

fecal oral route

gastro oral

oral oral

Question 2

What are the basic characteristics of H.Pylori?

Answer 2

gram negative 
shaped like a curved rod
2-6 flagella
tests positive for urease, oxidase and catalase
Microaerophile

Question 3

How does H.pylori survive in the stomach?

Answer 3

H.pylori uses adhesin proteins to stick to foveolar cells and releases virulence factors such as urease.

Urease converts urea into CO2 and ammonia which neutralises the gastric acid protecting it from the acidic environment

Question 4

What does cagA do?

Answer 4

cytotoxin-associated gene A, interferes with attachments between epithelial cells that help protect underlying mucosal layers. This induces an inflammatory immune response within the gastric lining, called gastritis.

In chronic infections, cagA has been linked to the development of two gastric cancers: mucosa-associated lymphoid tissue or MALT lymphoma, which involves B cells;

and adenocarcinoma, which involves cells within the gastric glands.

Question 5

What does VacA do?

Answer 5

vacA causes epithelial cell death and exposes the underlying mucosal layers to gastric acid.

As more and more cell layers die, deep holes through the mucosa form called ulcers.

Question 6

What is the result of inflammation in the stomach?

Answer 6

inflammation also stimulates the G cells to secrete gastrin, which in turn stimulates parietal cells to produce even more hydrochloric acid.

And all this excess acid can spur the formation of both gastric ulcers and duodenal ulcers

Question 7

How does the C14 breath test work?

Answer 7

H.Pylori is urease positive
urease splits urea to hydrogen and ammonia
patient ingests capsule containing radioactive C14
if present, C14 urea is broken down to HCO3 and excreted by lungs as CO2

Question 8

What is the difference between Urea breath test and H.pylori serology?

Answer 8

The major difference between H.pylori serology and a C14 breath test is that a true positive C14 Urea breath test tells you that the patient is actively infected with H.pylori.

H.pylori
serology cannot reliably distinguish between past or present infection.