Presence of potentially novel Helicobacter pylori-like organisms in gastric samples from cats and dogs

Abstract Currently, seven gastric non- Helicobacter pylori Helicobacter (NHPH) species are known to commonly colonize the stomach of cats and dogs, with a low pathogenic significance. Reports of H. pylori and H. pylori -like organisms infecting animals have occasionally been made. In this study, samples were collected from the corpus and antrum of 20 cats and 27 dogs. A Helicobacter genus-specific 16S rRNA PCR assay, H. pylori -specific ureAB and glmM PCR assays and a nested PCR detecting 23S rRNA in a Helicobacter genus-specific manner in the first step and a H. pylori -specific manner in the second step were performed, in combination with sequencing. Histopathological and anti- Helicobacter immunohistochemical evaluations were also performed. Based on 16S rRNA sequence analysis, 39/47 animals (83%) appeared infected with canine/feline gastric NHPHs in the corpus and/or antrum. H. pylori -specific ureAB amplicons were obtained in samples of 22 stomachs (47%). One canine antrum sample positive in the ureAB assay was also positive in the H. pylori -specific glmM assay. While 36/47 (77%) animals had a positive sample in the first step of the nested 23S rRNA PCR assay, all samples were negative in the final step. Sequence analysis of obtained amplicons and immunohistochemistry point towards the presence of unidentified H. pylori -like organisms in cats and dogs. Histopathological examination suggests a low pathogenic significance of the gastric Helicobacter spp. present in these animals. In conclusion, cats and dogs may be (co-)infected with gastric Helicobacter organisms other than the known gastric NHPHs. Culture and isolation should be performed to confirm this hypothesis.