HELICOBACTER-CANIS SP-NOV, A NEW SPECIES FROM DOGS - AN INTEGRATED STUDY OF PHENOTYPE AND GENOTYPE

A group of Campylobacter-like organisms (CLOs) were isolated from the faeces of diarrhoeic or healthy dogs, constituting 4% of all CLOs from this source. Since they formed a unique DNA homology group within the genus Helicobacter, and exhibited distinctive phenotypic properties, they were collectively termed the HC group. A polyphasic taxonomic ana lysis was made of this group. The phenotype of four dog isolates and a single human isolate was unique and could be distinguished bacteriolo gically from other helicobacters. Electron microscopic ultrastructure revealed defining characteristics of Helicobacter. The 16S rRNA gene o f the nominated type strain NCTC 12739T was sequenced, and its analysi s delineated the group as a new species of Helicobacter. This conclusi on was supported by relative DNA homology and whole-cell protein elect rophoretic patterns. We therefore propose the name Helicobacter canis sp. nov. for this group. The species most closely related to H. canis sp. nov. were H. cinaedi, 'Flexispira rappini' and H. fennelliae. A sp ecies-specific recombinant DNA probe was cloned from NCTC 12739T for u se in routine laboratory identification and epidemiological studies. T he faecal source, bile tolerance and lack of urease activity of H. can is sp. nov. suggest that this new Helicobacter species colonizes the l ower bowel rather than the stomach.