Related Experiment Videos
Differentiation of clinical Helicobacter pullorum isolates from related Helicobacter and Campylobacter species
P L Melito1, D L Woodward, K A Bernard
1National Laboratory for Enteric Pathogens, Special Bacteriology Laboratory, Bureau of Microbiology, Laboratory Center for Disease Control, and Cangene Corporation, Winnipeg, Manitoba, Canada.
Background:
Helicobacter pullorum, first detected in the liver and intestinal contents of poultry, was defined as a new species in 1994. This organism has since been isolated from humans with gastroenteritis. Phenotypic as well as genotypic methods have been used to identify H. pullorum associated with cases of human disease.
Materials And Methods:
Clinical isolates were submitted for identification to the National Laboratory for Enteric Pathogens by Provincial Public Health Laboratories within Canada. Phenotypic characterization was conducted using a variety of growth and biochemical tests including oxidase, catalase, indoxyl acetate, H2S production in triple sugar iron (TSI) agar, antimicrobial susceptibility testing, and fatty acid analysis. Genotypic identification was performed using a polymerase chain reaction-restriction fragment-length 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. pullorum were detected from patients with gastroenteritis for inclusion in this study. Typically, these isolates were oxidase and catalase positive, produced 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 TSI, and only 2 showed tolerance to 1% bile. Antimicrobial susceptibility assays indicated that 6 of the 11 strains were resistant to nalidixic acid. The fatty acid profiles of the isolates were similar to each other and provided a distinguishing profile from the other related species. Genetically identical and distinct species-specific restriction fragment-length polymorphism (RFLP) patterns were produced using the restriction enzymes Bsr I and Dde I.
Conclusion:
Phenotypic and genotypic procedures were used to identify H. pullorum. 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. The use of a combination of phenotypic and, in particular, genotypic markers for H. pullorum should prove valuable both for epidemiological investigations and for the diagnosis of disease related to this emerging human pathogen.
Insights
Helicobacter pullorum, an emerging pathogen causing gastroenteritis, was identified using phenotypic and genotypic methods. This study highlights its distinct characteristics and the value of a polyphasic approach for diagnosis and epidemiology.
Area of Science:
- Microbiology
- Infectious Diseases
Background:
- Helicobacter pullorum, identified in 1994, is increasingly isolated from human gastroenteritis cases.
- Both phenotypic and genotypic methods are employed for identifying H. pullorum in clinical settings.
Purpose of the Study:
- To characterize clinical isolates of Helicobacter pullorum.
- To evaluate phenotypic and genotypic methods for H. pullorum identification.
Main Methods:
- Phenotypic characterization included oxidase, catalase, H2S production, antimicrobial susceptibility, and fatty acid analysis.
- Genotypic identification utilized polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) of the 16S rRNA gene.
Main Results:
- Eleven H. pullorum isolates from gastroenteritis patients were analyzed.
- Most isolates were oxidase/catalase positive, grew at 42°C, and produced H2S.
- Antimicrobial susceptibility revealed nalidixic acid resistance in 6/11 strains; PCR-RFLP provided distinct species-specific patterns.
Conclusions:
- Phenotypic and genotypic methods are crucial for H. pullorum identification.
- Interspecies variability necessitates a polyphasic approach.
- H. pullorum shares similarities with Campylobacter coli and C. lari, requiring accurate diagnostic markers for epidemiological and clinical purposes.