Differential pathogenic effect of two Helicobacter-like organisms in dog gastric mucosa

Two forms of Helicobacter were detected in the gastric mucosa of twelve healthy beagle dogs. According to ultrastructural criteria they could be classified as Helicobacter bizzozeronii-like and Helicobacter felis-like species. In five animals, the light fundic load of Helicobacter bizzozeronii-like did not affect the integrity of the glandular epithelium. In three animals, the heavy bacterial load extended in the lumens of antral glands and coincided with increased intraepithelial lymphoid infiltrate. The heavy bacterial load observed in 4 animals was mixed (Helicobacter bizzozeronii-like and Helicobacter felis-like), fundic and antral, luminal and intracellular. Adherence of Helicobacter felis-like to epithelial cells and intracellular penetration were responsible for focal necrosis, and glandular atrophy might be observed. Helicobacter bizzozeronii-like thus appeared non pathogenic in beagle dogs, even when the heavy bacterial load extended to the antrum. By contrast, Helicobacter felis-like showed a constant pathogenic effect linked to its properties of adhesion and penetration into epithelial cells. A wider comparative study in humans and domestic carnivorous will determine if the latter may play a role of reservoir-host for pathogenic bacteria.