Helicobacter Pylori

Question 1

How helicobacter pyori are transmitted?

Answer 1

By ingestion of food or water

Question 2

What is the clinical presentation?

Answer 2

Chronic inflammatory gastritis = duodenal ulcer

Question 3

What are their virulence factors?

Answer 3

Urease, motility, adherence factors, heat labile cytotoxin, gastric mucin protease, hemolysin, lipopolysaccharides

Question 4

What’s the importance of the adherence factors?

Answer 4

For colonization

Question 5

Which 2 different products are coded by the bacterial chromosome?

Answer 5

One product has a cytotoxic activity, the other has a vacuolating activity of glands, leading to their atrophy

Question 6

What’s the importance of the gastric mucin protease?

Answer 6

To buffer the pH of the gastric mucin

Question 7

What’s the function of hemolysins?

Answer 7

Break down RBCs

Question 8

What is the optimal pH? Which part of the stomach has this pH?

Answer 8

Their optimal pH is 7

The mucosa of the stomach is the area of optimal growth of H. pylori

Question 9

What is the site of infection during the acute stage? Where bacteria colonize?

Answer 9

The gastric antrum
Bacteria are present in the mucus overlying the mucosa. Colonization extends to the gastric glands but the mucosa isn’t invaded by bacteria

Question 10

What is the outcome of the acute stage?

Answer 10

There is a superficial active gastritis infiltrated with inflammatory cells and PMN

Question 11

What does the hemolysin?

Answer 11

It breaks the hemoglobin releasing hemin

Question 12

How the medium become more alkaline and protecting the bacteria?

Answer 12

Ammonia by urease activity covers the bacteria to make the medium more alkaline, along with the gastric mucin protease, this creates a buffering, protecting the bacteria.

Question 13

What are the symptoms of the acute stage?

Answer 13

Acute achlorhydric gastritis, nausea, abdominal pain, flatulence and bad breath because of the ammonia

Question 14

When there is a progression to chronic gastritis and atrophic gastritis?

Answer 14

When achlorhydric gastritis stays for a year even after recovery

Question 15

Which virulence factors are associated with the bacteria in peptic ulceration during the chronic stage?

Answer 15

Vac A (vacuoating protein) and Cag A (cytotoxicity associated protein)

Question 16

What can influence the outcome of infection during this stage?

Answer 16

Host factors like age (when age increases infection increases), how many times we have been infected and if we had developed Ab

Question 17

Where are present genes for Vac A and Cag A?

Answer 17

on the pathogenicity island of H. pylori.

Question 18

Where the bacteria invades? What is the outcome?

Answer 18

To lower layers

There will be atrophic gastritis

Question 19

What will happen if individuals don’t take the proper treatment?

Answer 19

Manifestations would last longer, especially abdominal pain and achlorhydric gastritis

Question 20

Where bacteria invades during gastric cancer?

Answer 20

Bacteria are no more between the mucus layer and the mucosa, they invade the mucosa layer

Question 21

What causes the formation of cancer?

Answer 21

Bacteria will multiply for a short period, they direct the cells causing them to replicate

Question 22

Why antibiotics or no longer effective in this period?

Answer 22

Since bacteria will disappear after that cancer is established

Question 23

Which type of cancer we will have?

Answer 23

MALT lymphoma

Question 24

What’s the cure when individuals reach the stage of cancer?

Answer 24

Once cancer state is reached there is no longer cure

Question 25

What is done to make the invasive tests?

Answer 25

A biopsy is taken from the pyloric end of the stomach or the surrounding by 5 cm. We use a part of the biopsy for each test

Question 26

For which tests the biopsy is used?

Answer 26

Histopathology and microscopy Culture Biopsy urease test

Question 27

What is the importance of histopathology even when bacteria can’t be found?

Answer 27

It allows us to see the tissue changes during carcinoma

Question 28

On which medium H. pylori can grow?

Answer 28

On blood agar plate

Question 29

What are the results of the oxidase and catalase tests?

Answer 29

Oxidase positive and catalase positive

Question 30

Are they gram negative or positive? | What is their shape?

Answer 30

They are gram-negative spiral bacteria

Question 31

Where biopsy is put in the biopsy urease test?

Answer 31

A piece of biopsy is put into urea with an indicator

Question 32

What indicates the presence of urease?

Answer 32

If there is a pH change, there was production of ammonia, so there is urease

Question 33

Why biopsy urease test is better than culture and histopathology?

Answer 33

Since it is a very quick method that gives results within 2 hours

Question 34

Which one are non-invasive tests?

Answer 34

Serology Urea breath test Fecal antigen test PCR

Question 35

Which test is used in serology? Which antibodies are detected?

Answer 35

ELISA to detect certain Ab (IgM, IgG, IgA) against certain antigens

Question 36

What is the procedure of the urea breath test? | What happens if H. pylori is present?

Answer 36

The patient swallows in a capsule containing an isotope of carbon C13 or C14 If H. pylori is present, the isotope will be in the exhaled CO2 (urea + water + urease —> CO2 + ammonia). For detection, we need a spectrophotometer.

Question 37

What is the danger concerning this test?

Answer 37

The danger is that C14 is radioactive | The test is not as easy as the biopsy urease test, though it is not invasive

Question 38

What detects the fecal antigen test?

Answer 38

We have kits containing Ab to different Ag to detect H. pylori antigens in fecal specimens. It gives quick results.

Question 39

Which specimens can be taken for PCR?

Answer 39

Saliva, dental plaques, water and fecal specimens

Question 40

Is there production of protective Ab after the first time of infection?

Answer 40

No protective Ab after the first time of infection

Question 41

When protective Ab are produced? | At which age individuals become protected?

Answer 41

The second time of infection | At the age of 60, enough Ab are produced so individuals are protected. It is an additive effect.

Question 42

What’s the antibiotic treatment? | Is there any vaccine?

Answer 42

A combination of 3 drugs for at least one week: omeprazole (which is a proton lowering pump inhibitor, increases the activity of the 2 other antibiotics, it is not an antibiotic but a drug), Clarithromycin and metronidazole No vaccine