Serotypes and putative virulence markers of Streptococcus suis isolates from cats and dogs.

Thirteen isolates of Streptococcus suis from cats and dogs were characterised. Formamide extracts of 10 of the 13 cultures reacted with group D specific antiserum, and serotyping of the cultures with specific antisera against capsular types 1 to 28 revealed the serotypes 9, 20, 1/2, 22, 26 and 4; the remaining cultures were untypable. In addition one of the cultures reacted with monoclonal antibodies against muramidase-released protein and in parallel with monoclonal antibodies against the extracellular factor (EF) of S suis. The latter reacted with proteins with a molecular weight of more than 150,000 indicating that the strain exhibited EF-related proteins. One of the 13 cultures haemagglutinated erythrocytes from human beings and various animal species and adhered in large numbers to HeLa cells.