Helicobacter pylori

What are some examples of bad unwanted bacteria in the stomach?

Salmonella

Shigella

Campilobacter

Vibrio cholerae

These all survive for short time only because cannot colonize

How does Helicobacter pylori survive and colonise? (what does it need?)

1 - adhesion molecules such as sugars on stomach epithelium

2 - movement mechanism - flagella to move around stomach

3 - degradative enzymes

4 - acid neutralizing system

as a result of this mucus layer and epithelial cells no longer protected against gastric acid

What does the H. pylori acid neutralization system consist of?

urease and proton gated urea channel

urea enters through pores in outer membrane, Hpurel allows urea in H.pyloti inner membrane urease catalyses hydrolysis of urea into ammonia and carbon dioxide, carbon dioxide diffuses into blood, ammonia accepts protons which raises ph

How can we test for h. pylori?

Non invasive - urea breath test, stool antigen test, serologic test

invasive - gastroscopy and biopsy

How does the urea breath test work?

Measures the enzyme urease unique to H. pylori

Test is highly specific and sensitive (>95%)

How is urea breath test carried out?

Urea drink consumed labeled with C13

urease catalyses hydrolysis of urea into ammonia and co2

diffusion of co2 into blood

circulation in blood

13co2 exhalation is collected for analysis

How is stool antigen test carried out?

Antibodies are key components of the immune system

antibodies can bind antigens

we can utilize this in tests to detect antigens of interest using lateral flow chromatography

How is the serelogic test carried out?

Antibodies can bind on antigens

Laboratory based as detection occurs from blood

used to see if patient has any antibodies against h. pylori produce by immune system