Extensive 16S rRNA gene sequence diversity in Campylobacter hyointestinalis strains: taxonomic and applied implications.

Phylogenetic relationships of Campylobacter hyointestinalis subspecies were examined by means of 16S rRNA gene sequencing. Sequence similarities among C. hyointestinalis subsp. lawsonii strains exceeded 99.0%, but values among C. hyointestinalis subsp. hyointestinalis strains ranged from 96.4 to 100%. Sequence similarities between strains representing the two different subspecies ranged from 95.7 to 99.0%. An intervening sequence was identified in certain of the C. hyointestinalis subsp. lawsonii strains. C. hyointestinalis strains occupied two distinct branches in a phylogenetic analysis of the genus Campylobacter, emphasizing the need for multiple strain analysis when using 16S rRNA gene sequence comparisons for taxonomic investigations.