[Surface characteristics of Streptococci: evaluation technics].

We examined the surface characteristics of 41 strains of Streptococci by using the salt aggregation technique (SAT). While group B, C, D and G Streptococci showed a clearly hydrophilic surface, 57.5% of group A strains revealed so hydrophobic characters as to be autoaggregating. Either the hydrophobicity or the autoaggregation of these Streptococci decreased after subsequent culture passages. A comparison has been done for 5 strains by the hydrophobic interaction chromatography (HIC) demonstrating a good correlation between the two techniques. As the only presence of M protein did not seem to condition the surface characteristics, however treatments with different proteolytic enzymes modify greatly the bacterial surface suggesting the involvement of various protein structures.