Classification of Erysipelothrix strains on the basis of restriction fragment length polymorphisms.

Restriction fragment length polymorphisms of the 16S rRNA genes of Erysipelothrix strains were studied by cleavage of the chromosomal DNA with restriction endonuclease EcoRI, followed by hybridization to a 420-bp internal fragment of the 16S rRNA gene. Thirty-two Erysipelothrix type and reference strains were classified, together with seven field strains. Reference strains of all serotypes and the type strains of Erysipelothrix rhusiopathiae and Erysipelothrix tonsillarum were included. Nine ribopatterns were observed. Pattern A was represented by 16 strains and included strains of serotypes 1b, 2 to 8, 11 to 13, 15 to 17, 19, and 23. Pattern B was represented by two strains (serotypes 1a and 9). Pattern C was represented by five strains (serotypes 5, 6, and 21). Pattern D was represented by one strain of serotype 4. Pattern E was represented by 11 strains of serotypes 2, 7, 10, 20, 22, 24, and 25. Patterns F, G, H, and I were each represented by a single strain of serotypes 26, 2, 18, and 3, respectively. All the different ribopatterns had some bands in common. Patterns B, C, and D were most similar to pattern A, while patterns F, G, H, and I resembled pattern E. Partial sequencing of the 16S rRNA gene of nine selected strains resulted in three different sequences, i.e., the typical E. rhusiopathiae sequence, the E. tonsillarum sequence, and a third sequence found for two strains. Strains of the same serotype were found to have different ribopatterns as well as different partial 16S rDNA sequences.