Helicobacter pylori testing and diagnosis

The presence of H. pylori may be confirmed by:

• microscopy for characteristic rod bacilli
• culture of H. pylori on selective media
• "urea breath test" - production of radiolabelled CO2 from swallowed urea - the most accurate test for H pylori (1)
• stool antigen test
• serology
  • antibodies to urease - this method cannot be used for judging eradication because antibody titres fall slowly
  • some kits provide a rapid result while the patient waits ("near patient test"). Laboratory based tests with a high sensitivity are useful but much less accurate (specific) than other methods. Near patient blood tests are less accurate still and are not recommended (1)
• gastric biopsy
• assay for anti-H. pylori IgG antibodies in saliva

A review of H pylori testing suggested that (2):

• both the 13C-urea breath and stool antigen tests are accurate methods for testing for H. pylori after eradication therapy
• serological tests are of no value in confirming successful eradication, as the antibody persists long after successful eradication
• C-urea breath tests and stool antigen tests are generally more accurate than serological tests and they can be used both pre- and post-treatment

PHE guidance states (3)

Preferred tests for H pylori:

• Urea breath tests and stool antigen tests (SATs) are the preferred tests
  • UBT or SAT should not be performed within two weeks of PPI,or four weeks of antibiotics,as these drugs supress bacteria and can lead to false negatives

Results:

• if H pylori positive then treatment indicated
• if negative test then 
  • only retest for HP if DU, GU, family history of cancer, MALToma, or if test was performed within two weeks of PPI, or four weeks of antibiotics (NPV of all tests is >95%)

Reference:

1. BSG (2002). Dyspepsia management guidelines.
2. Drug and Therapeutics Bulletin 2004; 42(9):71-2.
3. PHE (February 2019). Test and treat for Helicobacter pylori (HP) in dyspepsia.