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

While seven gastric non- Helicobacter pylori Helicobacter (NHPH) species are known to commonly colonize the stomach of cats and dogs, the potential of H. pylori and H. pylori -like organisms to infect animals remains controversial and was investigated in this study using gastric samples of 20 cats and 27 dogs. A Helicobacter genus-specific 16 S rRNA PCR assay, H. pylori -specific ureAB and glmM PCR assays and a nested PCR detecting 23 S rRNA in a Helicobacter genus-specific manner in a first round of PCR and a H. pylori -specific manner in a second round, were performed in combination with sequencing. Histopathological and anti- Helicobacter immunohistochemical evaluations were also performed. Based on 16 S 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 round of the nested 23 S rRNA PCR assay, all samples were negative in the second round. 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.