Sixty-seven strains of the five described Salmonella serotypes having antigens 6,7[ratio ]c[ratio ]1,5, that is
S. enterica serotype Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var.
Decatur, Paratyphi C, and Typhisuis, were examined for 16S rrn profile ribotype, presence of
IS200 and phenotypic characters, including rate of change of flagellar-antigen phase and
nutritional character. Choleraesuis sensu stricto and its Kunzendorf variant had related but
distinct ribotypes. Therefore, ribotyping appears to be a suitable method for differentiating
Choleraesuis non-Kunzendorf from Choleraesuis var. Kunzendorf. Some strains of Paratyphi C
had 16S profiles that resembled that of Choleraesuis non-Kunzendorf, while others resembled
that of Choleraesuis var. Kunzendorf. The Typhisuis profiles were like those of Choleraesuis
non-Kunzendorf, while the Choleraesuis var. Decatur profiles were unlike those of any of the
other four groups. Furthermore, IS200 fingerprinting discriminated between Choleraesuis var.
Decatur and the other strains with antigenic formula O6,7[ratio ]c[ratio ]1,5, and comparison of IS200
patterns showed a high degree of genetic divergence within Choleraesuis var. Decatur. Our
findings show that ribotyping and IS200 fingerprinting, combined with classical microbiological
methods, distinguish the groups Choleraesuis non-Kunzendorf, Choleraesuis var. Kunzendorf,
Choleraesuis var. Decatur, Paratyphi C and Typhisuis.