Why use stool sample in checking H. pylori?
Q - We have been asked to provide stool as well as blood samples when checking for H. pylori. Why?
A - Faecal antigen tests are an alternative, non-invasive and cost-effective test for diagnosis and confirmation of cure. Serological methods are inappropriate for monitoring therapy as antibodies stay for months after successful eradication.
Guidelines from the European Helicobacter Pylori Study Group state:
· A 'test and treat' approach should be used in adult patients with persistent dyspepsia under the age of 45 (the age cut-off may vary locally), having excluded those with predominantly gastro-esophageal reflux disease symptoms, NSAID users and patients with alarm symptoms or family history of gastric cancer.
· Diagnosis of infection should be by urea breath test (UBT) or stool antigen test.
· Always test for successful eradication, by UBT, or endoscopy-based test if endoscopy is indicated. Stool antigen test is the alternative if UBT is not available.
· In uncomplicated duodenal ulcer patients eradication therapy does not need to be followed by further antisecretory treatment.
· If second-line quadruple therapy fails in primary care, patients should be referred.
· H. pylori eradication is not generally indicated for extra-alimentary disease.
Dr Nandini Shetty is a consultant microbiologist in the Health Protection Agency Collaborating Centre, University College London Hospitals