Is there a test to diagnose H. pylori infection?
Accurate and simple tests for the detection of H. pylori infection are available (H. pylori infection tests). They include blood antibody tests, urea breath tests, stool antigen tests, and endoscopic biopsies.
Blood tests for the presence of antibodies to H. pylori can be performed easily and rapidly. However, blood antibodies can persist for years after complete eradication of H. pylori with antibiotics. Therefore, blood antibody tests (immunoglobulin G or IgG and/or IgA) may be good for diagnosing infection, but they are not good for determining if antibiotics have successfully eradicated the bacterium.
The urea breath test (UBT) is a safe, easy, and accurate test for the presence of H. pylori in the stomach. The breath test relies on the ability of H. pylori to break down the naturally occurring chemical, urea, into carbon dioxide, which is absorbed from the stomach and eliminated from the body in the breath. Ten to 20 minutes after swallowing a capsule containing urea labeled with either a minute amount of radioactive carbon or heavy but not radioactive carbon, a breath sample is collected and analyzed for labeled carbon dioxide. The presence of labeled carbon dioxide in the breath (a positive test) means that there is active infection. The test becomes negative (there is no radioactive carbon dioxide in the breath) shortly after eradication of the bacterium from the stomach with antibiotics. Individuals who are concerned about even minute amounts of radioactivity can be tested with urea labeled with heavy, nonradioactive carbon.
Endoscopy is an accurate test for diagnosing H. pylori as well as the inflammation and ulcers that it causes. For endoscopy, the doctor inserts a flexible viewing tube (endoscope) through the mouth, down the esophagus, and into the stomach and duodenum. During endoscopy, small tissue samples (biopsies) from the stomach lining can be removed. A biopsy specimen is placed on a special slide containing urea (for example, CLO test slides). If the urea is broken down by H. pylori in the biopsy, there is a change in color around the biopsy on the slide. This means that there is an infection with H. pylori in the stomach. Endoscopy also allows determination of the severity of gastritis with biopsies as well as the presence of ulcers, MALT lymphoma, and cancer.
Biopsies also may be cultured in the bacteriology laboratory for the presence of H. pylori; however, this is done infrequently since other simpler tests are available.
Stool sample: A recently-developed test for H. pylori is a test in which the presence of the bacterium can be diagnosed from a sample of stool. The test uses an antibody to H. pylori to determine if H. pylori antigen is present in the stool. If it is, it means that H. pylori is infecting the stomach. Like the urea breath test, in addition to diagnosing infection with H. pylori, the stool test can be used to determine if eradication has been effective soon after treatment.
In 2012, the FDA gave approval for the urea breath test to be done in children aged 3 years to 17 years old.