CAMPYLOBACTER-HYOINTESTINALIS SUBSP LAWSONII SUBSP-NOV, ISOLATED FROMTHE PORCINE STOMACH, AND AN EMENDED DESCRIPTION OF CAMPYLOBACTER-HYOINTESTINALIS

The taxonomic relationships of seven isolates obtained from porcine st omachs (the ''CHY'' group), which resembled (but were distinct from) t he type strain and other reference strains of Campylobacter hyointesti nalis, were examined by using phenotypic and genomic methods. The phen otypic characteristics and ultrastructure of the new organisms were ch aracteristic of Campylobacter species, although they could be distingu ished from all previously described taxa. A numerical analysis of 38 p henotypic characters revealed that the new isolates formed a distinct group at a similarity level of 90.1% and could be clearly distinguishe d from reference strains representing 20 related taxa, principally spe cies and subspecies belonging to the genera Campylobacter, Arcobacter, and Helicobacter. DNA-DNA hybridization studies revealed that the por cine stomach strains were genomically homogeneous (levels of relatedne ss, 84 to 90%), although the levels of DNA homology with type and refe rence strains of C. hyointestinalis were relatively high (56 to 71%). Differences in the DNA base compositions of the CHY group and C. hyoin testinalis strains were also observed. Our data indicate that the new porcine isolates should be considered members of a subspecies of C. hy ointestinalis, for which we propose the name Campylobacter hyointestin alis subsp. lawsonii subsp. nov. The type strain is strain CHY 5 (= LM G 14432 = NCTC 12901 = CCUG 34538). The description of C. hyointestina lis is emended accordingly, and a description of Campylobacter hyointe stinalis subsp. hyointestinalis subsp. nov, is given.