Testing meningeal strains of Streptococcus suis to detect M protein genes

Previous reports have suggested that the surface proteins found in meningeal strains of Streptococcus suis might be similar to the M protein of group A streptococci. Fifty-five strains of S suis, including human and swine meningeal and pneumonic isolates, were tested for M protein genes by dna probes representing the constant domain of the 3′ end of the group A, M protein gene. None of the S suis strains examined was positive, indicating that these organisms either lack M protein genes or harbour different genes, not expressing the constant domains of protein M from group A.