Helicobacter pylori is a corkscrew-shaped, gram-negative rod that lives in the mucous layer of the stomach. H. pylori infection is now accepted as the most common cause of gastritis, and is etiologically involved in gastric ulcer, duodenal ulcer, gastric adenocarcinoma and primary gastric B-cell lymphoma. The organism is very common, infected at least half of the world’s population. H. pylori infection is typically acquired in childhood. Once acquired, infection persists chronically, probably continuing in the stomach throughout life. The diagnostic tests for H. pylori can be classified into two categories: Invasive and Noninvasive tests.
Direct detection by invasive test procedures requires an endoscopy and biopsy specimens from antrum and stomach body. Although the procedure is highly specific and high positive predictive value, the cost and discomfort to the patients are very high.
The most widely available noninvasive test is probably the serological based test. The serology test detects H. pylori specific IgG antibody in patient serum with current or prior infection. Serology test is a simple, convenient test with relative high sensitivity. The main limitation of serology test is the inability to distinguish current and past infections. Antibody may be present in the patient’s serum long after eradication of the organism.
The urease breath test (UBT) with 14C or 13C labeled urea, is a noninvasive test based on the urease activity of the organism and is highly sensitive and specific.The UBT requires a high density