Helicobacter pylori is a spiral, gram negative bacterium which is strongly associated with chronic type B gastritis in humans. A negative H. pylori antibody titre is highly predictive that the patient does not have H. pylori infection, unless the sample is drawn too early for the colonization of bacteria. A positive result, does not differentiate between acute or past infection, and may merit further evaluation if symptoms persist after treatment.
For patients undergoing treatment, a drop in IgG concentrations by > 60 % are highly predictive of bacterial eradication.