History, Treatment

Question 1

How do you check for treatment success

Answer 1

Stop PPIs two weeks before testing as H.pylori is slow growing and may give false negs if tested for earlier

No antibiotics or DeNol for 4 weeks

Retest with the urea breath test or endoscopy test

Question 2

2nd/3rd line treatment for H.pylori

Answer 2

Levofloxacin 500mg bd

amoxycillin 1g bd

PPI full dose bd

for 10-14 days

Question 3

Alternative first line when clarithromycin resistance is prevalent

Answer 3

PPI

Amoxycillin

metronidazole

clarithromycin

for 10-14 days

Question 4

First line treatment in other countries and second line treatment in the uk

Answer 4

Bismuth subcitrate or subsalicylate i qds

tetracycline HCL 500mg qds

Metronidazole 400mg tds (3x a day)

PPI full dose bd

for 2 weeks

Question 5

First line treatment for H.pylori infection where there is clarithromycin resistance <15%

Answer 5

PPI (omeprazole 20 mg bd)

Clarithromycin 500mg bd

Amoxycillin 1g bd or metronidazole 400mg

for 1-2 weeks

Question 6

What is the first line of treatment of H.pylori infection in countries with high resistance?

Answer 6

PPI + Amoxycillin + metronidazole + clarithromycin for 10-14 days

Question 7

Describe the urea breath test

Answer 7

Patient ingests carbon 13 urea

The urea would be broken down by urease if H.pylori is present as urease is only present in bacteria and not in human GI tract.

This would lead to the formation of CO2 which is breathed out by the patient

The breath of the patient is then tested with mass spec for the presence of carbon 13

Question 8

Examples of non invasive methods of H. pylori diagnosis

Answer 8

Serology

Urea Breath Test*

Stool antigen test

Question 9

The endoscopic methods of H.pylori diagnosis

Answer 9

Biopsy urease test

Histology

Culture

Question 10

Eradication of H. pylori also treat these four medical conditions

Answer 10

Gastric ulcer

Duodenal ulcers

Gastric MALT lymphoma

Functional dyspepsia

Question 11

Three factors that affect the severity of H. pylori disease

Answer 11

Bacterial virulence

Host susceptibility

Environmental factrs (diet, lifetstyle-smoking increase chances)

Question 12

What are the factors of H.pylori’s resistance

Answer 12

Adherence to the surface of the mucosa protecting it from the immune response

Immune evasion

Nutrient acquisition: they feed off the stomach lining using virulence factors

Question 13

What are the three mechanisms used by H. pylori for colonization of the host?

Answer 13

Chemotaxis

Motility

Acid resistance

Question 14

What is the importance of the following equation?

CO(NH2)2 + H2O——-> 2NH3 + CO2

Answer 14

Essential for colonization beneath the mucosa of the stomach

Stimulates the immune response

Used in the urea breath test and biopsy urease test (yellow to red colour change)

Persistently expressed at a high level of infection

Subunit vaccine component

Question 15

Explain why the urease test is appropriate to test for H.pylori.

Answer 15

CO(NH2)2 + H2O ——-> 2NH3 + CO2

                         urease

In acidic condition (the stomach) urea enters the periplasm of H. pylori

The protons first cross the periplasm of H. pylori which is detected by the UreI pore.

These now acidic condtions cause the UreI pore to open allowing the urea to enter the cytoplasm of H. pylori

As 20-30% of the H.pylori cells i made up of urease, the urea is then broken down by the enzyme as seen in the equation above.

The ammonia produced then neutralizes the conditions in the periplasm

Question 16

Three methods of H.pylori acquisition

Answer 16

mother to child/primary care giver to child

person to person contact

oro-oral route

Question 17

Describe the age cohort effect of H.pylori in developed countries

Answer 17

In developed countries, H. pylori is more common in individuals over the age of ten as the younger members of the population would have immunity passed onto them through their mothers breast milk however since the H.pylori infection persists lifelong you would still find that a high percentage of adult have it since it would’ve been acquired in childhood

Question 18

Describe the age cohort effect that occurs in developed countries when it comes to H.pylori

Answer 18

Most children in developing countries contract H.pylori at a younger age in nursery and have it for the rest of their lives. But due to better nutrition and health care choices the amount of children who contract it has decreased leading to a higher percentage of H.pylori in older individuals.

Question 19

What are the steps for H.pylori eradication

Answer 19

Two weeks of the following

PPI: omeprazole 20mg bd for acid reduction

2-3 weeks of antibiotics

Question 20

Koch’s Postulates

Answer 20

Organism must be shown to be constantly present in characteristic form and arrangement

The organism responsible for the disease must be isolated and grown in pure culture

The pure culture must be shown to induce the disease experimentally

Question 21

The father of Helicobacter pylori

Answer 21

Barry Marshall