HP and gastric lymphoma: However, to date clinical observations or in vitro and in vivo experiments for Hp biofilm studies have been primarily limited to be mono-microbial, exclusively to Hp. There are only a couple of studies that demonstrated the presence of non-Hp bacterial aggregates in the gastric mucus layer and crypts of the patients during acid suppression treatment or with gastric primary lymphoma, using chemical and immunochemical staining (Jonkers et al., 1997; Sanduleanu et al., 2001).