Gastritis and peptic ulcer are major illnesses that affect a significant number of individuals each year. Since the discovery of H. pylori in 1983, many reports suggest a relationship between the presence if H. pylori and gastrointestinal disorders. Evidence of such a correlation between the presence of H. pylori on gastric mucosal of patients with histological confirmed gastric, and peptic ulcer disease simulated the development of serological techniques for the detection of antibodies to H. pylori . Many reports have shown that such serological techniques are simple and convenient for the detection of H. pylori in infected individuals. Detection of IgG antibodies against H. pylori in patient serum has been shown to be an aid for the detection of H. pylori infection in symptomatic patients. The presence of proteins associated with CagA and VacA genes in the antigenic mixture, in addition to major antigenic components such as urease, are essential for the detection of H. pylori by serological methods. Antibodies to CagA and VacA proteins are found in-patients with peptic ulcer.

The titers of antibodies to H. pylori, after eradication of H. pylori will remain at a detectable level for a period of time. Hence, antibody testing cannot differentiate between current and past infection. Therefore, a combination of antibody-antigen testing may be a better diagnostic strategy for the determination of H. pylori in GI tracts of infected individuals. Such methods, however, require biopsy specimens and patients must undergo expensive, unpleasant, costly and time-consuming endoscopies procedures.

A noninvasive method, the urea breath test, which detects the urease activity of H. pylori, has also been used to determine the presence of H. pylori in upper part of GI tract. This method uses 13C or 14C-urea and it too is expensive, time-consuming, and unpleasant, requiring skilled technicians and specialized instrumentations.

The PYLORI DETECT ANTIGEN (PDA) is an ELISA-based assay that detect H. pylori antigen in human stool. This qualitative assay does not require specific instruments. It is recommended that this test be performed in conjunction with antibody assay (PYLORI DETECT IgG assay manufactured by Micro Detect, Inc). Positive results obtained by both assays show the current ongoing infection by H. pylori.