Identification and epidemiological typing of Campylobacter hyointestinalis subspecies by phenotypic and genotypic methods and description of novel subgroups

Twenty-eight type, reference, and field strains classified as, or closely resembling Campylobacter hyointestinalis, were characterised by phenotypic tests, whole-cell protein-, and macrorestriction profiling. The phenotypic, and protein data, were objectively evaluated by numerical analyses. Each of the methods employed were able to differentiate isolates classified as C. hyointestinalis subsp. hyointestinalis and C. hyointestinalis subsp. lawsonii. However, two strains of the latter proved to be phenotypically atypical. These strains appeared to be closely related and may represent an atypical lineage of this taxon. Two novel, distinct groups of C. hyointestinalis-like bacteria, originally isolated from the cloacae of Canada geese and human diarrhoeic stools, were also identified by each of the methods used. This appears to be the first report confirming the presence of C. hyointestinalis-like strains from birds and may be significant since the carriage of campylobacters in other avian species is a known risk factor in the dissemination of enteric disease. This study shows that strains resembling C. hyointestinalis should be characterised more extensively in order to accurately establish their identity and thus provide important information regarding the prevalence, importance, and epidemiology of the defined subspecies, and the novel groups described here. Simultaneous identification and subtyping of each taxon can be effected by protein- and/or macrorestriction profiling.