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Introduction
1. Anatomy
2. Microbiology
2.1 General bacteriology
2.2 Introduction to systemic bacteriology
2.3 Gram positive cocci
2.4 Gram negative cocci
2.5 Gram positive bacilli
2.6 Gram negative bacilli
2.7 Other important bacteria
2.7.1 Overview
2.7.2 Helicobacter pylori
2.7.3 Campylobacter jejuni
2.7.4 Haemophilus influenzae
2.7.5 Bordetella pertussis
2.7.6 Legionella pneumophila
2.7.7 Brucella
2.7.8 Mycobacteria
2.7.9 Actinomycetes
2.7.10 Nocardia
2.7.11 Mycoplasma pneumoniae
2.7.12 Treponema pallidum
2.7.13 Borrelia burgdorferi
2.7.14 Chlamydia / Chlamydophila
2.7.15 Rickettsia
2.7.16 Coxiella burnetii
2.7.17 Additional information
2.8 Virology
2.9 Parasitology
2.10 Mycology
3. Physiology
4. Pathology
5. Pharmacology
6. Immunology
7. Biochemistry
8. Cell and molecular biology
9. Biostatistics and epidemiology
10. Genetics
11. Behavioral science
Wrapping up
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2.7.2 Helicobacter pylori
Achievable USMLE/1
2. Microbiology
2.7. Other important bacteria

Helicobacter pylori

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It’s a spiral/helical/curved Gram negative bacterium that’s motile with a tuft of polar flagella. It’s strongly urease positive and also oxidase and catalase positive. It has a predilection for the gastric mucus glands.

Urease helps with invasion by neutralizing the acidic pH in the stomach, which allows the organism to survive. It also breaks down the stomach’s protective mucus layer, which predisposes to peptic ulcer disease.

Urease test
Urease test

All patients with peptic ulcer disease must be screened for H.pylori. Common tests include:

  • Urea breath test
  • Antigen detection in stool
  • IgG antibody detection from blood
  • Rarely, gastric mucosal biopsy

H.pylori has also been associated with chronic gastritis and MALT lymphomas (mucosa associated lymphoid tissue) and gastrointestinal B cell lymphomas. Interestingly, both peptic ulcer disease and MALT lymphomas are cured once H. pylori is eradicated from the body.

Helicobacter pylori: Characteristics

  • Spiral/helical, curved Gram negative bacterium
  • Motile with tuft of polar flagella
  • Strongly urease positive; also oxidase and catalase positive
  • Predilection for gastric mucus glands

Pathogenesis

  • Urease neutralizes stomach acid, aids survival
  • Urease breaks down protective mucus layer
  • Predisposes to peptic ulcer disease

Diagnosis

  • All peptic ulcer disease patients screened for H. pylori
  • Common tests:
    • Urea breath test
    • Stool antigen detection
    • Blood IgG antibody detection
    • Gastric mucosal biopsy (rare)

Associated Diseases

  • Chronic gastritis
  • Peptic ulcer disease
  • MALT lymphomas and GI B cell lymphomas
    • Both peptic ulcer disease and MALT lymphoma cured by H. pylori eradication

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Helicobacter pylori

It’s a spiral/helical/curved Gram negative bacterium that’s motile with a tuft of polar flagella. It’s strongly urease positive and also oxidase and catalase positive. It has a predilection for the gastric mucus glands.

Urease helps with invasion by neutralizing the acidic pH in the stomach, which allows the organism to survive. It also breaks down the stomach’s protective mucus layer, which predisposes to peptic ulcer disease.

All patients with peptic ulcer disease must be screened for H.pylori. Common tests include:

  • Urea breath test
  • Antigen detection in stool
  • IgG antibody detection from blood
  • Rarely, gastric mucosal biopsy

H.pylori has also been associated with chronic gastritis and MALT lymphomas (mucosa associated lymphoid tissue) and gastrointestinal B cell lymphomas. Interestingly, both peptic ulcer disease and MALT lymphomas are cured once H. pylori is eradicated from the body.

Key points

Helicobacter pylori: Characteristics

  • Spiral/helical, curved Gram negative bacterium
  • Motile with tuft of polar flagella
  • Strongly urease positive; also oxidase and catalase positive
  • Predilection for gastric mucus glands

Pathogenesis

  • Urease neutralizes stomach acid, aids survival
  • Urease breaks down protective mucus layer
  • Predisposes to peptic ulcer disease

Diagnosis

  • All peptic ulcer disease patients screened for H. pylori
  • Common tests:
    • Urea breath test
    • Stool antigen detection
    • Blood IgG antibody detection
    • Gastric mucosal biopsy (rare)

Associated Diseases

  • Chronic gastritis
  • Peptic ulcer disease
  • MALT lymphomas and GI B cell lymphomas
    • Both peptic ulcer disease and MALT lymphoma cured by H. pylori eradication