Helicobacter Pylori and Gastric Disease

What is Helicobacter pylori?

• gram-negative

• spiral-shaped

• microaerophilic

• flagellated

bacteria

What percentage of the world population is infected by H. Pylori?

50%

Where is the only place H. pylori can colonise?

gastric type muscosa

Where does H. pylori infection reside?

in the surface mucous layer, does not penetrate the epithelial layer

Pathogenesis of H. Pylori

1. enters host and survival

2. motility and chemotaxis

3. adhesin-receptor interaction establish colonisation

4. toxins release damage to host

5. intracellular replication

Where in the cell does intracellular replication of H. Pylori take place?

epithelium

What does the outcome of H. Pylori infection depend on?

• size of colonisation

• characteristics of bacteria

• host factors

  • genetic susceptibility

  • environmental factors

What are potential outcomes of H. Pylori infections?

• asymptomatic

• chronic gastritis

• chronic atrophic gastritis

• intestinal metaplasia

• gastric or duodenal ulcer

• gastric cancer

Effect on stomach acid in astral predominant gastritis from chronic H. pylori infection

increased acid

Effect on acid in corpus predominant gastritis from chronic H. pylori infection

decreased acid

Investigations for H. Pylori infection

• serology: IgG again H. pylori

• 13c / 14c urea breath test

• stool antigen test - ELISA - need to be off PPI for 2 weeks

• histology (gastric biopsies stained for the bacteria)

• culture of gastric biopsies

• rapid slide urease test (CLO)

What is the required to do a stool antigen test for H. pylori infection?

need to be off PPI for 2 weeks

What is gastritis?

inflammation in the gastric mucosa

Types of gastritis

Autoimmune (parietal cells)

Bacterial (H. pylori)

Chemical (bile / NSAIDs)

Most common cause of peptic ulcers

• H. Pylori infection

• NSAIDs

• smoking

Symptoms of peptic ulcer

• epigastric pain

• nocturnal / hunger pain

• back pain

• nausea and vomiting

• weight loss and anorexia

• haematemesis / melaena if ulcer bleeds

Management of peptic ulcers

• eradication therapy - if caused by H. Pylori

• antacid medication - PPIs (omeprazole) / H2 antagonists (ranitidine)

• stop NSAIDs

Eradication therapy for H. Pylori

triple therapy for 7 days:

• clarithromycin (500mg bd)

• amoxycillin (1g bd) (or metronidazole 400mg bd)

  • tetracycline if penicillin allergy

• PPI (omeprazole 20mg bd)

Complications of peptic ulcers

• acute bleeding - melaena and haematemesis

• chronic bleeding - iron deficiency anaemia

• perforation

• fibrotic stricture

• gastric outlet obstruction

Presentation of gastric outlet obstruction

• vomiting - lacks bile, fermented foodstuffs

• early satiety

• abdominal distension

• weight loss

• gastric splash

• dehydration and loss of H⁺ and Cl⁻ in vomit

• metabolic alkalosis

Management of gastric outlet obstruction

endoscopic balloon dilatation

Investigations for gastric outlet obstruction

• bloods - low Cl, low Na, low K, renal impairment

• Upper Gastrointestinal Endoscopy (UGIE)