Helicobacter canadensis sp nov isolated from humans with diarrhea as an example of an emerging pathogen

We recently analyzed 11 helicobacter isolates cultured from diarrhea patien ts in Canada. These isolates had been characterized biochemically by restri ction fragment length polymorphism (RFLP; AluI, HhaI) analysis and by fatty -acid analysis as Helicobacter pullorum. However, four of the isolates diff ered biochemically from H. pullorum by their inability to hydrolyze indoxyl acetate and their resistance to nalidixic acid. Using complete 16S rRNA an alysis, we determined that these four strains clustered near H. pullorum bu t had a sequence difference of 2% and therefore represent a novel helicobac ter, Helicobacter canadensis. This novel helicobacter could also be disting uished from Ii pullorum by RFLP analysis using ApaLI. The number of novel H elicobacter spp, associated with gastrointestinal disease in humans and ani mals is rapidly increasing. There are now six Helicobacter spp, isolated fr om diarrheic humans, the other five being Ii. pullorum, Ii. canis, "H, rapp ini," Ii fennelliae, and Ii cinaedi. This finding highlights the importance of careful molecular analysis in addition to standard biochemical tests in identifying the increasing number of Helicobacter spp, isolated from human s and animals.