Helicobacter pylori testing is used to diagnose an infection due to the bacteria and to evaluate the effectiveness of treatment. H. pylori infection is associated with an increased risk of developing ulcers (peptic ulcer disease), chronic gastritis, and gastric (stomach) cancer.
There are several different types of H. pylori testing that can be performed. Some require a sample of breath or stool while others are more invasive and require a tissue sample obtained using a procedure called endoscopy. Tests include:
Stool/fecal antigen test
Detects the presence of H. pylori antigen in a stool sample
Urea breath test
A person drinks a liquid containing a low level of radioactive material that is harmless or a nonradioactive material. If H. pylori is present in the person's gastrointestinal tract, the material will be broken down into "labeled" carbon dioxide gas that is expelled in the breath.
H. pylori antibody testing
Test not recommended for routine diagnosis or for evaluation of treatment effectiveness. Detects antibodies to the bacteria and will not distinguish previous infection from a current one. If test is negative, then it is unlikely that a person has had an H. pylori infection. If ordered and positive, results should be confirmed using stool antigen or breath test.
With Endoscopy: tissue biopsy sample obtained; good tests but less frequently ordered because invasive
Tissue examined under a microscope by a pathologist, who will look for H. pylori bacteria and any other signs of disease that may explain a person's symptoms.
Rapid urease testing
H. pylori produces urease, an enzyme that allows it to survive in the acidic environment of the stomach. The laboratory test can detect urease in the tissue sample.
The bacteria are grown on/in a nutrient media; results can take several weeks. This test is necessary if the health practitioner wants to evaluate which antibiotic will likely cure the infection. (See also Susceptibility Testing.)
Fragments of H. pyloriDNA are amplified and used to detect the bacteria; primarily used in a research setting.
The stool antigen test and urea breath test are recommended for the diagnosis of an H. pylori infection and for the evaluation of the effectiveness of treatment. These tests are the most frequently performed because they are fast and noninvasive. Endoscopy-related tests may also be performed to diagnose and evaluate H. pylori but are less frequently performed because they are invasive.
The testing recommendations come from recently published guidelines by the American Gastroenterology Association (AGA), the American College of Gastroenterologists (ACG), and the Infectious Diseases Society of America (IDSA) / the American Society for Microbiology (ASM).
Testing may be ordered when someone is experiencing gastrointestinal pain and has signs and symptoms of an ulcer. Some of these may include:
Abdominal pain that comes and goes over time
Unexplained weight loss
Feeling of fullness or bloating
Some people may have more serious signs and symptoms that require immediate medical attention, including sharp, sudden, persistent stomach pain, bloody or black stools, or bloody vomit or vomit that looks like coffee grounds.
H. pylori testing may also be ordered when a person has completed a regimen of prescribed antibiotics to confirm that the H. pylori bacteria have been eliminated. A follow-up test is not performed on every person, however.
A positive H. pylori stool antigen, breath test, or biopsy indicates that a person's gastrointestinal pain is likely caused by a peptic ulcer due to these bacteria. Treatment with a combination of antibiotics and other medications will be prescribed to kill the bacteria and stop the pain and the ulceration.
A positive blood test for H. pylori antibody may indicate a current or previous infection. A different test for H. pylori such as the breath test may need to be done as follow up to determine whether the infection is a current one.
A negative test result means that it is unlikely that the individual has an H. pylori infection and their signs and symptoms may be due to another cause. However, if symptoms persist, additional testing may be done, including the more invasive tissue biopsy, to more conclusively rule out infection.
The urea breath test is not typically recommended for young children. In children, the preferred test would be the stool antigen test.
People can have gastrointestinal pain for many reasons; an ulcer caused by H. pylori is only one of them.
If someone uses antacids within the week prior to testing, the rapid urease test may be falsely negative. Antimicrobials, proton pump inhibitors, and bismuth preparations may interfere with all but the blood antibody test.
This article was last reviewed on November 19, 2014. | This article was last modified on November 19, 2014.
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