Isolation of Helicobacter canis from a colony of bengal cats with endemic diarrhea

Abstract

On the basis of biochemical, phenotypic, and 16S rRNA analyses, Helicobacter canis was isolated from Bengal cats with and without chronic diarrhea. Because the cats were coinfected with other potential pathogens, including Campylobacter helveticus, and because H. canis was isolated from nondiarrheic cats, the causal role of H. canis in producing the diarrhea could not be proven. Histologically, the colons of the four affected cats were characterized by mild to moderate neutrophilic, plasmacytic, and histocytic infiltrates in the lamina propria. Rare crypt abscesses were also noted for three cats but were a more prominent feature of the colonic lesions noted for the fourth cat. This is the first observation of H. canis in cats and raises the possibility that H. canis, like H. hepaticus and H. bilis in mice, can cause inflammation of the colon, particularly in hosts with immune dysregulation. Further studies are needed to determine the importance of H. canis as a primary enteric pathogen in cats and the role of cats in the possible zoonotic spread of H. canis to humans.

FIG. 1

Electrophoresis of DNA amplified by Helicobacter-specific PCR on a 6% Visigel separation matrix with Helicobacter-specific primers. Lanes: M, 1-kb DNA ladder; 1, reagent control; 2, H. canis ATCC 51401; 3 to 10, DNAs extracted from feline fecal isolates.

FIG. 2

Comparison of RFLP patterns of the 1.2-kb Helicobacter-specific PCR product with restriction enzymes BfaI and HhaI. Lanes: M, 100-bp DNA ladder; 1, H. canis MIT dog isolate (14); 2, H. canis ATCC 51401; 3, MIT 98-152; 4, MIT 98-153.

FIG. 3

Phylogenetic tree constructed on the basis of 16S rRNA sequence similarity values. The two H. canis strains from diarrheic cats are in bold. Scale bar, 5% difference in nucleotide sequences, as determined by measuring the lengths of the horizontal lines connecting two species.