PCR-based diagnosis of Helicobacter species in the gastric and oral samples of stray dogs

Helicobacter spp. have been detected in different parts of gastrointestinal tract of dogs including the oral cavity, stomach, intestines and recently, hepatobilliary system. However, the transmission pathways of Helicobacter spp. have not been yet fully elucidated. Research in the last decade has proposed that oral–oral and fecal–oral transmissions, among others, may be a plausible route of this gastric infection. This study was carried out primarily to determine the existence of pylori and non-pylori Helicobacter spp. in the oral secretions and dental plaque of stray dogs of Iran as one of the possible routes of humans and animal infection and, secondly, to evaluate the accordance between oral and gastric colonization of Helicobacter spp. in these dogs. Forty-eight adult stray dogs were studied by PCR using 16S rRNA, Helicobacter felis, Helicobacter heilmannii, and Helicobacter pylori specific primers. Positive samples for 16S rRNA specific primers that did not meet the specified species of Helicobacter genus were randomly subjected to sequencing. Helicobacter spp. DNA was found in the oral and gastric specimens of 100 % of the stray dogs. There was not, however, any agreement between Helicobacter colonization at these two locations, at neither genus nor species level. Our study confirmed that the oral cavity of stray dogs routinely exposed to transient forms of bacteria and may temporarily harbor Helicobacter spp and Wolinella spp. Therefore, oral cavity as a source of Helicobacter spp. may act as a reservoir for transmission. However, it may not necessarily reflect the colonization status of the gastric mucosa.