The ecological niche in humans appears to be restricted to the stomach and duodenum. Patients who harbor the organism are divided into two basic groups: a) colonized and b) infected.   Patients who test positive for H. pylori yet have no signs or symptoms of gastrointestinal disease are considered “colonized”. Patients who test positive for H. pylori and present with signs or symptoms of gastrointestinal disease are considered “infected”.    The process by which a colonized individual becomes infected remains unclear.   The process by which patients become colonized is also still under investigation. Direct detection requires that an invasive biopsy be taken from the upper gastrointestinal tract. The presence of H. pylori is then confirmed by direct microscopic examination, rapid urease testing or culturing of the organism from the biopsy material.   This strategy has the advantage of being able to detect active infections while being highly specific with a very high positive predictive value.  
The invasive approach subjects the patient to unnecessary risk and discomfort.

In contrast, Doctor’s Data, Inc. offers the non-invasive HpSA enzyme immunoassay (EIA), an in vitro qualitative procedure for the detection of H. pylori antigens in human stool.   Test results can be used to diagnose H. pylori infection, and to monitor patient response during and post-therapy.   Current scientific literature indicates that testing to confirm eradication should be performed at least four weeks after the completion of therapy.