_i_H. pylori__i_ Testing
Also known as:H pylori; H-pylori; H. pylori antibody test; H. pylori stool antigen test; H. pylori breath test; Urea breath test; CLO test; Rapid urease test (RUT) for H. pylori
Formal name:Helicobacter pylori
Why Get Tested?
To diagnose an infection with Helicobacter pylori, bacteria that can cause peptic ulcers
When to Get Tested?
When you have symptoms of an ulcer, such as gastrointestinal pain that comes and goes, unexplained weight loss, nausea and/or vomiting
A stool sample, a breath sample, or a tissue biopsy of the stomach lining
Test Preparation Needed?
You may need to avoid certain medications; follow any instructions you are given.
How is it used?
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
|Histology||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.|
|Culture||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.)|
|PCR (polymerase chain reaction)||Fragments of H. pylori DNA 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).
When is it ordered?
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.
What does the test result mean?
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.
Is there anything else I should know?
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.
What is being tested?
Helicobacter pylori is a type of bacteria that is known to be a major cause of peptic ulcer disease. H. pylori testing detects an infection of the gastrointestinal (GI) tract caused by the bacteria.
H. pylori is very common, especially in developing countries. The bacteria are present in (colonize) the stomachs and intestines of as many as 50% of the world's population. Most of those affected will never have any symptoms, but the presence of H. pylori increases the risk of developing ulcers (peptic ulcer disease), chronic gastritis, and gastric (stomach) cancer. The bacteria decrease the stomach's ability to produce mucus, making the stomach prone to acid damage and peptic ulcers.
There are several different types of H. pylori testing that can be performed. Some are less invasive than others.
- Stool antigen test - detection of H. pylori in a stool sample
- Urea breath test - detection of labeled carbon dioxide in the breath after drinking a solution
Recommendations for these tests come from 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).
An antibody test using a blood sample is not recommended for routine diagnosis or for evaluation of treatment effectiveness. This test detects antibodies to the bacteria and will not distinguish between a present and previous infection. If the antibody 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 a stool antigen or breath test.
Invasive tests using an endoscopy procedure are less frequently performed than noninvasive tests because they require a tissue biopsy collection. Tests include:
- Histology - examination of tissue under a microscope
- Rapid urease testing - detects urease, an enzyme produced by H. pylori
- Culture - growing H. pylori in/on a nutrient solution
How is the sample collected for testing?
The sample collected depends on the test ordered. For the urea breath test, a breath sample is collected and then the person is given a liquid to drink. Another breath sample is collected at a timed interval. For the stool antigen test, a stool sample is collected in a clean container.
A more invasive test will require a procedure called an endoscopy, which involves putting a thin tube with a tiny camera on the end down the throat into the stomach. This allows for visualization of the stomach lining as well as the ability to take a small piece of tissue (a biopsy) from the lining for examination.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
For the breath test, you may be instructed to refrain from taking certain medications:
- Four weeks before the test, do not take any antibiotics or oral bismuth subsalicylate (Pepto Bismol®).
- Two weeks before the test, do not take any prescription or over-the-counter proton pump inhibitors, such as omeprazole, lansoprazole, or esomeprazole.
- One hour before the test, do not eat or drink anything (including water).
If submitting a stool sample or having a tissue biopsy collected, it may be necessary to refrain from taking any antibiotics, antacids, or bismuth treatments for 14 days prior to the test.
If undergoing endoscopy, fasting after midnight on the night prior to the procedure may be required.
- What is the treatment of peptic ulcer caused by Helicobacter pylori?
Treatment usually involves a combination of antibiotics and drugs to reduce the amount of stomach acid produced, such as proton pump inhibitors and histamine receptor blockers, as well as a bismuth preparation, such as Pepto-Bismol®, taken for several weeks.
- Does everyone with H. pylori get ulcers?
No, many people have evidence of infection but have no symptoms of ulcerative disease. The reason why some people with H. pylori infections develop peptic ulcers and others do not is not yet understood.
- Should everyone be tested for H. pylori?
Since the infection is very common and most people do not ever get ulcers, testing is generally only recommended for those who have signs and symptoms.
- How did I get infected with H. pylori?
The bacteria are believed to be transmitted by eating food or drinking water that has been contaminated with human fecal material, or possibly through contact with the stool, vomit, or saliva of an infected person. Exposure to family members with H. pylori seems to be the most likely opportunity for transmission.
- Does everyone treated for H. pylori get better?
The majority of people who successfully complete the combination antibiotic therapy get rid of these bacteria from their GI tract. However, resistance to some of the antibiotics may occur and, therefore, the bacteria may continue to multiply in spite of appropriate therapy.
- Can I get another H. pylori infection?
Treatment does not make a person immune, so there is always the potential for becoming infected again.
- Why is the blood test for H. pylori antibodies not recommended?
The American Gastroenterology Association, the American College of Gastroenterologists, the Infectious Diseases Society of America and the American Society for Microbiology do not recommend the antibody blood test for routine use in diagnosing an H. pylori infection or evaluating its treatment as the test cannot distinguish between a present and previous infection. However, some health practitioners still use this test. If the blood test is negative, then it is unlikely that the person has had an H. pylori infection. If it is positive, then the presence of a current H. pylori infection should be confirmed with a stool antigen or breath test.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
Descriptions of clinical laboratory tests were originally prepared for use on Lab Tests Online, an award-winning patient education website on clinical laboratory testing. Lab Tests Online is produced by the American Association for Clinical Chemistry (AACC), a global scientific and medical professional organization dedicated to clinical laboratory science and its application to healthcare. The Lab Tests Online website is developed in collaboration with other laboratory professional societies and is funded in part through corporate sponsorships.