HELICOBACTER CANIS ISOLATED FROM A DOG LIVER WITH MULTIFOCAL NECROTIZING HEPATITIS

On the basis of biochemical, phenotypic, and 16S rRNA analysis, a nove l gram-negative bacterium, isolated from normal and diarrheic dogs as well as humans with gastroenteritis, has been recently named Helicobac ter canis, A 2-month-old female crossbred puppy was submitted to necro psy with a history of weakness and vomiting for several hours prior to death, The liver had multiple and slightly irregular yellowish foci u p to 1.5 cm in diameter, Histologically, the liver parenchyma containe d randomly distributed, occasionally coalescing hepatocellular necrosi s, often accompanied by large numbers of mononuclear cells and neutrop hils, Sections of liver stained by the Warthin-Starry silver impregnat ion technique revealed spiral- to curve-shaped bacteria predominantly located in bile canaliculi and occasionally in bile ducts, Aerobic cul ture of liver was negative, whereas small colonies were noted on Campy lobacter selective media after 5 days of microaerobic incubation, The bacteria were gram negative and oxidase positive but catalase, urease, and indoxyl acetate negative; nitrate was not reduced to nitrite, and the organism did not hydrolyze hippurate, The bacteria were also resi stant to 1.5% bile. Electron microscopy revealed spiral-shaped bacteri a with bipolar sheathed flagella. By 16S rRNA analysis, the organism w as determined to be H. canis, This is the first observation of H. cani s in active hepatitis in a dog and correlates with recent findings of Helicobacter hepaticus- and Helicobacter bilis-related hepatic disease in mice. Further studies are clearly warranted to ascertain whether H . canis-associated hepatitis is more widespread in canines as well as a cause of previously classified idiopathic liver disease in humans.