Helicobacter pylori

Helicobacter pylori


Morphology

  • Spiral-shaped
  • Gram-negative
  • Motile bacterium with lopotrichous flagella, 5-6 flagella
  • Microaerophilic
  • With its flagella and its spiral shape, the bacterium drills into the mucus layer of the stomach, and can either be found suspended in the gastric mucosa or attached to epithelial cells.
Epidemology
  • All children in developing counteries have immunity by five years of age
  • “Today, helicobacters colonise the stomach of half the human population of the world”.
  • Developed countries   -30%
  • Developing countries > 80%
  • H. pylori is usually acquired in childhood but immunity does not develop.
  • Low socioeconomic status is a risk factor for H. pylori positivity.
Biochemical test
  • Oxidase, Urease and catalase-positive
Culture
  • Incubated at 37oC in microaerophilic condition.
  • Media -Skirrow’s medium, chocolate medium
Pathogenesis
Diseases
  • Duodenal Ulcer(commonest cause)
  • Gastric (Stomach) Ulcer
  • Non-Ulcer dyspepsia Weird Syndromes (associated with acne rosacea, gulf veterans syndrome, chronic fatigue syndrome and chronic halitosis)
  • Stomach Cancer
  • MALT Lymphoma
Laboratory diagnosis
Noninvasive tests
Serology
  • Detect an immune response by examining a blood sample for antibodies to the organism (ELISA).
Urea breath test
  • A urea solution labelled with C14 isotope is given to pt.
  • The C02 subsequently exhaled by the pt contains the C14 isotope and this is measured. 
  • A high reading indicates presence of H. pylori.

 Faecal antigen test

  • Detects H. pylori antigens in faecal specimens.

Polymerase chain reaction (PCR)

  • Can detect HP within a few hours. Not routine in clinical use.

 Urease Test

  • Urease activity in the stomach qualitatively detects active infection with a sensitivity and specificity of more than 90 percent.
Invasive testing
Histological examination
  • Of biopsy specimens of gastric/duodenal mucosa take a endoscopy
Culture
  • Not sensitive then a skilled microscopy histological section
  • Can be used for antibiotic resistance testing 
  • Requires selected agars and incubation periods
Treatment
  • No treatmnet for asymptomatic
1st line:Regimen 1
  • 14 days
  • PPI(proton pump inhibitors) BD
  • Clarithromycin 500 mg BD
  • Amoxicillin 19 BD (or Metronidazole 500 mg BD in penicillin allergic)
1st line: Regimen 2– 10 days
  • PPI BD
  • Amoxicillin 1g BD (days 1-5)
  • Days 6-10 Clarithromycin 500 mg + Metronidazole 500 mg both BD

2nd line

  • Omeprazole, Bismuth, Tetracycline, iletronidazole (OBTM)
Treatment assessment test-
Stool antigent test, Urea test, biopsy based test.

Exam Important

Morphology

  • Spiral-shaped
  • Gram-negative
  • Motile bacterium with lopotrichous flagella, 5-6 flagella
  • Microaerophilic.
Epidemology
  • All children in developing counteries have immunity by five years of age
  • “Today, helicobacters colonise the stomach of half the human population of the world”.
  • Developed countries   -30%
  • Developing countries > 80%
  • H. pylori is usually acquired in childhood but immunity does not develop.
  • Low socioeconomic status is a risk factor for H. pylori positivity.
Biochemical test
  • Oxidase, Urease and catalase-positive
Culture
  • Incubated at 37oC in microaerophilic condition.
  • Media -Skirrow’s medium, chocolate medium
Diseases
  • Duodenal Ulcer(commonest cause)
  • Gastric (Stomach) Ulcer
  • Non-Ulcer dyspepsia Weird Syndromes (associated with acne rosacea, gulf veterans syndrome, chronic fatigue syndrome and chronic halitosis)
  • Stomach Cancer
  • MALT Lymphoma
Laboratory diagnosis
Noninvasive tests
1.Serology
  • Detect an immune response by examining a blood sample for antibodies to the organism (ELISA).
2.Urea breath test
  • A urea solution labelled with C14 isotope is given to pt.
  •  The C02 subsequently exhaled by the pt contains the C14 isotope and this is measured. 
  • A high reading indicates presence of H. pylori.

3. Faecal antigen test.

4.Polymerase chain reaction (PCR)

5.  Urease Test

  • Urease activity in the stomach qualitatively detects active infection with a sensitivity and specificity of more than 90 percent.
Invasive testing
Treatment
  • No treatmnet for asymptomatic
1st line:Regimen 1
  • 14 days
  • PPI(proton pump inhibitors) BD
  • Clarithromycin 500 mg BD
  • Amoxicillin 19 BD (or Metronidazole 500 mg BD in penicillin allergic)
1st line: Regimen 2- 10 days
  • PPI BD
  • Amoxicillin 1g BD (days 1-5)
  • Days 6-10 Clarithromycin 500 mg + Metronidazole 500 mg both BD

2nd line

  • Omeprazole, Bismuth, Tetracycline, iletronidazole (OBTM)
Treatment assessment test-
Stool antigent test, Urea test, biopsy based test.

 

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