Differentiation of clinical Helicobacter pullorum isolates from related Helicobacter and Campylobacter species

Background. Helicobacter pullorum, first detected in the liver and intestin al contents of poultry, was defined as a new species in 1994. This organism has since been isolated from humans with gastroenteritis. Phenotypic as we ll as genotypic methods have been used to identify H. pullorum associated w ith cases of human disease. Materials and Methods. Clinical isolates were submitted for identification to the National Laboratory for Enteric Pathogens by Provincial Public Healt h Laboratories within Canada. Phenotypic characterization was conducted usi ng a variety of growth and biochemical tests including oxidase, catalase, i ndoxyl acetate, H2S production in triple sugar iron (TSI) agar, antimicrobi al susceptibility testing, and fatty acid analysis. Genotypic identificatio n was performed using a polymerase chain reaction-restriction fragment-leng th polymorphism (PCR-RFLP) analysis of a 1-kb fragment of the Helicobacter 16S rRNA gene. Results. During the last 7 years (1993-1999) a total of 11 isolates of H. p ullorum were detected from patients with gastroenteritis for inclusion in t his study. Typically, these isolates were oxidase and catalase positive, pr oduced optimal growth at 42 degrees C, and produced H2S in TSI. Of these 11 isolates, 1 showed DNase activity, while another did not produce H2S in TS I, and only 2 showed tolerance to 1% bile. Antimicrobial susceptibility ass ays indicated that 6 of the 11 strains were resistant to nalidixic acid. Th e fatty acid profiles of the isolates were similar to each other and provid ed a distinguishing profile from the other related species. Genetically ide ntical and distinct species-specific restriction fragment-length polymorphi sm (RFLP) patterns were produced using the restriction enzymes Bsr I and Dd e I. Conclusions. Phenotypic and genotypic procedures were used to identify H. p ullorum. Interspecies phenotypic variability was apparent and supported the use of a polyphasic approach for identification. Similarities to the more prominent human pathogens Campylobacter coli and C. lari were also noted. T he use of a combination of phenotypic and, in particular, genotypic markers for H. pullorum should prove valuable both for epidemiological investigati ons and for the diagnosis of disease related to this emerging human pathoge n.