DISTINCT GENOTYPES OF HUMAN AND CANINE ISOLATES OF CAMPYLOBACTER-UPSALIENSIS DETERMINED BY 16S RIBOSOMAL-RNA GENE TYPING AND PLASMID PROFILING

The utility of combined 16S rRNA (rrs) gene restriction fragment lengt h polymorphism and plasmid profiles to differentiate between and withi n Campylobacter upsaliensis of human and canine origin was examined. F ourteen distinct rrs gene restriction fragment length polymorphs consi sting of bands sized between 1.9 and 4.8 kb were observed. The copy nu mber of the 16S rRNA gene was three in most strains of C. upsaliensis. Plasmids were found in almost 60% of the strains; ranging in size fro m 1.5 to 100 kb, they gave 15 distinct plasmid profiles. All isolates from humans contained one or more plasmids, as did strains isolated fr om dogs with sporadic diarrhea. The two commonest 16S ribotypes were d ivided into eight and nine subgroups by plasmid profiling, The genotyp ing of canine isolates from three veterinary surveys detected both mul tiple infections and reinfection of dogs. Except for one, each of the isolates from humans constituted a single and unique 16S ribotype, and these more frequently carried plasmids than did canine strains. Ribot ypes of human strains were not found among canine isolates. These resu lts suggest that host-specific genotypic differences may exist among s trains of C. upsaliensis, for example, intraspecific clones or clone c omplexes pathogenic for humans.