Evidence of Helicobacter spp. in Saliva and Gastric Mucosa of Domestic Dogs in the Central Region of Rio Grande do Sul, Brazil.

Daniel D Guerra Segundo,Saulo T L Pinto Filho,Bernardo N Antunes,Luís F Pedrotti,Camila B E Mello,Omar G Velasquez,Letícia R Martins,Juliana F Cargnelutti,Mariana M Flores,Vanessa Milech,Douglas Morck

doi:10.1155/2021/8857231

Abstract

Helicobacter pylori is a spiral-shaped bacterium, which plays a role in the aetiology of gastric diseases in humans. Non-H. pylori Helicobacter (NHPH) species naturally colonise the stomach of animals and also induce gastric lesions in humans, highlighting their zoonotic importance. We evaluated the gastric bacterial colonisation density and gastric lesions and sought to identify the main phylogenetic groups of the Helicobacter spp. obtained from dogs in the central region of Rio Grande do Sul, Brazil, with this study aiming to investigate the occurrence of Helicobacter spp. in saliva and gastric samples from these dogs. This study included 35 dogs and used analysis such as cytology, histopathology, PCR, rapid urease testing, and phylogenetic analysis. Of the dogs, 94.3% were positive for Helicobacter spp., and these bacteria were present in the stomach of 32 dogs and saliva of eight. Respectively, eight, 15, and nine dogs had mild, moderate, and severe colonisation. Lymphocytic-plasmacytic infiltrate was the main gastric lesion. However, the presence of Helicobacter and the density appeared to be unrelated to the gastric lesions. The samples possessed a high nucleotide identity with remarkably similar sequences among some of the species of NHPH such as H. heilmannii s.s., H. salomonis, H. felis, and H. bizzozeronii. The saliva of domestic dogs, even of those who appear clinically healthy, can cause Helicobacter infection in humans and other animals, with, in these dogs, increased density, occurrence rate, and predominance of NHPH of zoonotic importance being found in the stomach with a lower occurrence of Helicobacter spp. in the saliva.

Highlights

Helicobacter spp. are spiral-shaped mobile Gram-negative bacteria with tropism for the gastric mucosa of humans and animals [1]
In samples of gastric mucosa from humans, another spiral-shaped bacteria with similar morphological features to H. pylori was documented, and this microbe was found to be remarkably similar to the spiral-shaped bacteria found in the gastric mucosa of domestic animals [4]. is new spiral bacteria was later classified by Solnick et al [5] as Helicobacter heilmannii
Phylogenetic studies were later employed utilising the 16 rRNA target gene, and these studies found instead that this bacteria belonged to a range of several Helicobacter species isolated from domestic and wild animals, such as H. felis, H. bizzozeronii, H. salomonis, Helicobacter heilmannii sensu stricto (H. heilmannii s.s.), H. bılis, H. cynogastricus, and H. baculiformis [6]. erefore, in order to organise this large group of bacteria into a single

Summary

Introduction

Helicobacter spp. are spiral-shaped mobile Gram-negative bacteria with tropism for the gastric mucosa of humans and animals [1]. Further research has shown that humans are the natural host of H. pylori and have established this species as the primary aetiology of peptic ulcers and gastric neoplasms [3]. Phylogenetic studies were later employed utilising the 16 rRNA target gene, and these studies found instead that this bacteria belonged to a range of several Helicobacter species isolated from domestic and wild animals, such as H. felis, H. bizzozeronii, H. salomonis, Helicobacter heilmannii sensu stricto (H. heilmannii s.s.), H. Dogs are the natural hosts of NHPH and harbour this bacteria in their gastric mucosa, gut, and oral cavity; gastric juice, saliva, and faeces are possible sources of transmission for this bacteria to infect humans [9,10,11]. The main species of NHPH found are H. heilmannii s.s, H. bizzozeronii, H. salomonis, H. felis, and H. canis [9, 11]

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