DISTRIBUTION OF SEROTYPE, VIRULENCE MARKERS AND FURTHER CHARACTERISTICS OF STREPTOCOCCUS-SUIS ISOLATES FROM PIGS

This study was designed to comparatively investigate 28 S. suis cultures isolated from various pathological processes of pigs. All cultures could be identified biochemically and most of the cultures could be serogrouped with specific antiserum against Lancefield's serogroup D. Serotyping of the S. suis isolates mainly revealed capsular types 2, 1, and 22. In addition, part of the cultures, mostly those of serotype 2, reacted with monoclonal antibodies to the virulence protein muraminidase-released protein, and, in parallel with monoclonal antibodies against the virulence protein extracellular factor. Independently of serotype and the occurrence of both virulence proteins, four cultures haemagglutinated erythrocytes from pigs, humans and rabbits. The haemagglutination reaction appeared to be related to the surface hydrophobicity of the isolates. However, part of the cultures with hydrophobic surfaces did not haemagglutinate the available erythrocyte preparations. The surface characteristics of the S. suis isolates shown in this investigation could be used to characterize individual isolates of S. suis that might be of importance for epidemiological studies.