Serological classification of Australian strains of Erysipelothrix rhusiopathiae isolated from pigs, sheep, turkeys and man.

154 strains of Erysipelothrix rhusiopathiae from pigs, sheep, turkeys and man were serotyped by using the double diffusion gel precipitation test. Ten of the 18 serotypes were detected in 151 of the strains. Three strains failed to react with any of the type specific antisera. It was found that serotype 1a shared an antigen(s) with serotype 1b, and that serotype 6 shared an antigen(s) with serotype 14. Serotype 2a and 2b were difficult to distinguish. Since serotypes 1 and 2 were isolated from cases of septicaemia in pigs, and since serotypes 1, 2, 4 and 7 were isolated from cases of arthritis, it was suggested that factors other than serotype were important in causing the various forms of swine erysipelas. The fact that the distribution of serotypes 1a, 1b and 2b between septicaemic and arthritic pigs was similar supported the conclusion that arthritis was consequent to bacteraemia. Serotypes 1a, 1b, 2b, 5, 12 and 15 were isolated from cases of arthritis in sheep, and serotypes 1a and 5 from cases of erysipelas in turkeys. Serotype 2b was isolated from a human specimen.