H. Pylori & Gastric Disease Flashcards
What is Heliobacter Pylori?
A gram -ve, spiral shaped, microaerophilic, flagellated bacterium carried by around 50% of the worlds population
Where does Heliobacter Pylori colonise?
The mucouse layer of the gastric mucosa only.
It doesnt penetrate into the epithelium or anywhere else
How does Heliobacter Pylori cause a problem?
It releases ammonia which can provoke an immune response and is also toxic to the epithelium, as are other chemicals released by Heliobacter Pylori
What does a Heliobacter Pylori cause?
Chronic gastritis leading to:
- In most people no significant disease
- If predominant in the body -> Loss of acid, gastric atrophy and finally gastric cancer
- If predominantly in the antrum -> Rise in acid -> Duodenal ulcers
What determines the outcome of a Heliobacter Pylori infection?
- Site
- Environmental factors e.g. smoking
- Genetic susceptibility
- Bug characteristics (virulence factors)
Define virulence factors?
Molecules produced by certain strains of a micro organism which give it an advantage at colonising or harming the host.
In what ways can we diagnose Heliobacter Pylori infection?
Non-Invasive:
- Stool Antigen Test (ELISA)
- Urea Breath Test
- Serology (IgG test)
Invasive (by Upper GI endoscopy):
- Staining of gastric biopsy
- Culture of biopsy
- Rapid slide urease test
Explain the rapid slide urease test?
Biopsy of mucosa isplaced in a medium with urea and a pH indicator
> Urease converts urea to ammonia and CO2
pH rises
Indicator changes colour
Urease is an enzyme produced by Heliobacter Pylori
Explain the Urea breath test?
- Urea tagged with an unusual isotope of carbon is breathed in
- Bacteria converts to ammonia + CO2
- Unusual isotope of carbon detected in breathed out CO2
What is the best invasive vs non-invasive way of detecting Heliobacter Pylori?
Stool Antigen Test (ELISA)
Rapid slide Urease Test
How do we eradicate a Heliobacter Pylori infection?
7 days of triple therapy:
- Clarithromycin
- Amoxicillin (tetracycline if penicillin allergic)
- A Proton Pump Inhibitor (PPI) e.g. Omeprazole
Further 2nd line protocols should this fail
Define Dyspepsia?
Also known as indigestion.
A condition of impaired digestion causing symptoms such as: - Upper abdominal pain/discomfort - Anorexia - Bloating - Nausea / Vomiting - Fullness and early satiety - Heartburn Retrosternal pain
How common is dyspepsia?
Around 80% of people get it occasionally with no serious underlying disease
Define a functional disorder?
One which impairs normal function of the gut without any detectable pathology.
Define an organic disorder:
Any disease in which there is detectable pathology. Either micro or macroscopic
Give some examples o dyspepsia causing conditions and whether they are functional or organic?
Functional:
- Psychological (psychological factors are very important in many functional disorders)
- Non-ulcer Dyspepsia
- IBS
- Drugs
Organic:
- Peptic Ulcer
- Gastritis
- Gastric Cancer
- Coeliac Disease
- Colonic Cancer