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
When would an upper GI endoscopy be indicated for dyspepsia?
If it came with any of the ALARMS symptoms:
- Anorexia
- Loss of Weight
- Anaemia
- Recent Onset >55 yrs or Persistant despite Treatment
- Melaena/Haematemesis or Mass
- Swallowing problems (Dysphagia/Odynophagia)
Define Haematemesis?
Vomiting blood
Define Odynophagia?
PAin when swallowing
NAme a few drugs that can cause dyspepsia
NSAIDs & Steroids
Ca Antagonists
Theophyllines
Nitrates
What is the flow chart approach to dyspepsia?
Dyspepsia:
- Alarms features?
- > Yes = Upper GI endoscopy
- No = Age?
- > Over 55 = UGIE
- Under 55 = Heliobacter Pylori test
- > If +ve do eradication therapy and or symptom treatent with antacids (PPIs or H2R antagonists) and change lifestyle factors
What are H2R antagonists?
Histamine H2 receptor antagonists
What lifestyle factors affect dyspepsia?
Smoking
Drinking
Diet
Lack of exercise
Loss of weight is an indicator
Define Gastritis
Inflammation in the gastric mucosa
How is gastritis diagnosed?
The clincal features can be seen on endoscopy then its confirmed histologically wiht a biopsy
What are the 3 typs of Gastritis?
A - Autoimmune (attacking parietal cells -> low HCl)
B - Bacterial (Heliobacter Pylori)
C - Chemical (Bile/NSAIDs)
What types of peptic ulcer are more common and with who?
Duodenal over gastric
Men more than women
Older more than younger
What can cause a peptic ulcer?
Heliobacter Pylori NSAIDs Smoking In rare cases: - Zollinger-Elison Syndrome - Hyperparathyroidism - Crohn's Disease
What are the symptoms of a peptic ulcer?
- Epigatric pain which may be relieved by antacids (point tenderness over diffuse)
- Pain at night or when hungry (more often a DU)
- Back Pain (may be a penetrating DU)
- Nausea or vomiting
- Weight loss/anorexia
If it bleeds you might get haematemesis or melaena
It often appears as just epigastric pain or tenderness
How is a peptic ulcer treated?
Antibiotics if its Heliobacter Pylori
Antacids:
- PPIs (omeprazole)
- H2 receptor antagonist (ranitidine)
Stop any NSAIDs
Surgery - but only if complicated
Complications of a peptic ulcer?
Acute Bleeding:
- Melaena
- Haematemesis
Chronic Bleeding:
- Iron deficient anaemia
Perforate
Gastric outlet Obstruction:
- Oedema
- Fibrotic Stricture
What is gastric outlet obstruction?
Gastric outlet obstruction is not a single entity; it is the clinical and pathophysiological consequence of any disease process that produces a mechanical impediment to gastric emptying.
Clinically it appears:
- Vomiting, fermented foodstuffs not bile
- Early Satiety
- Abdominal Distension
- Weight Loss
- Gastric Splash
- Dehydration
- Loss of HCl in vomit -> Metabolic Alkalosis
What tests can we do for gastric outlet obstruction?
Bloods:
- Low Cl, Na, K
- Renal Impairment
Upper GI endoscopy:
- Prolonged Fast First or aspirate gastric contents
- Then identify if its a stricture, ulcer or cancer
How do we treat gastric outlet obstruction?
Treat the underlying cause:
- If its a stricture use Endoscopic Balloon Dilatation
- Otherwise it often requires surgery
How common is gastric cancer and what histological types is it?
Second most common GI cancer
5 yr survival <20%
Most are adenocarcinomas in the glandular epithelium. Can also be a lymphoma (MALT) or sarcoma (GIST)
MALT and GIST?
MALT = Mucosa Associated Lymphoid tissue GIST = GastroIntestinal Stromal Tumour
How do patients with gastric cancer present?
- Dyspepsia
- Early Satiety
- Nausea & Vomiting
- Weight Loss
- GI bleeding (haematemesis/Malaena)
- Fe deficient anaemia
- Gastric Outlet obstruction
Explain the aetiology of gastric cancer?
None of these are a direct cause but all are associated with gastric cancer:
- Diet
- Genes
- Heliobacter Pylori
- Smoking
- Previous Gastric pathology or resection
- Biliary Reflux
- Family History
Explain the inheritance of gastric cancer?
- Most are actually sporadic with no demonstratable inherited component
- <15% show familial clustering
- 1-3% of cases are a heritable gastric cancer syndrome
How do we investigate a case of gastric cancer?
An upper GI endoscopy with biopsy to confirm using a histological diagnosis.
Then stage with a chest and abdominla CT checking:
- Lymph nodes
- Lungs
- Liver
- Peritoneum
- Marrow
How do we treat gastric cancer?
Surgery
Chemotherapy
DUH!
