Helicobacter pylori was previously referred to as Campylobacter pyloridis. It is a gram-negative, microaerophilic bacterium found in the stomach of patients with gastritis and gastric ulcers. The type II strain is a causative bacteria linked to duodenal ulcers, MALT lymphomas, and stomach cancers.
Detection of H. pylori can be accomplished with the use of commonly obtainable rabbit polyclonal antibodies that work well with proteolytic enzyme pepsin as tissue section pretreatment or monoclonal antibody (clone ULC3R) that requires heat-induced epitope retrieval (HEIR) and citrate buffer. Monoclonal antibody clone ULC3R does not cross-react with Campylobacter jejuni (a gastric bacterium which causes infective diarrhea) unlike polyclonal antibodies to H. pylori. Detection with an horseradish peroxidase (HRP) or alkaline phosphatase (AP) detection system is very straight forward. (Ref6) (Ref7)
H. pylori bacteria are demonstrated in gastrointestinal tissue (top image) using mouse monoclonal antibody, clone ULC3R. HRP labeled detection system with DAB chromogen is used. In the lower image, rabbit polyclonal antibody and a HRP labeled detection system with DAB chromogen is utilized.