Confirming the presence of H. pylori is important once the doctor has diagnosed an ulcer because elimination of the bacteria is likely to cure ulcer disease. Blood, breath, and stomach tissue tests may be performed to detect the presence of H. pylori. While some of the tests for H. pylori are not approved by the U.S. Food and Drug Administration (FDA), research shows these tests are highly accurate in detecting the bacteria. However, blood tests on occasion give false positive results, and the other tests may give false negative results in people who have recently taken antibiotics, omeprazole (Prilosec®), or bismuth (Pepto-Bismol®).
Blood tests
Blood tests such as the enzyme-linked immunosorbent assay (ELISA) and quick office-based tests identify and measure H. pylori antibodies. The body produces antibodies against H. pylori in an attempt to fight the bacteria. The advantages of blood tests are their low cost and availability to doctors. The disadvantage is the possibility of false positive results in patients previously treated for ulcers since the levels of H. pylori antibodies fall slowly. Several blood tests have FDA approval.
Breath tests
Breath tests measure carbon dioxide in exhaled breath. Patients are given a substance called urea with carbon to drink. Bacteria break down this urea and the carbon is absorbed into the blood stream and lungs and exhaled in the breath. By collecting the breath, doctors can measure this carbon and determine whether H. pylori is present or absent. Urea breath tests are at least 90 percent accurate for diagnosing the bacteria and are particularly suitable to follow-up treatment to see if bacteria have been eradicated. These tests are awaiting FDA approval.
Tissue tests
If the doctor performs an endoscopy to diagnose an ulcer, tissue samples of the stomach can be obtained. The doctor may then perform one of several tests on the tissue. A rapid urease test detects the bacteria's enzyme urease. Histology involves visualizing the bacteria under the microscope. Culture involves specially processing the tissue and watching it for growth of H. pylori organisms.
