[Changes in surface characteristics of group A streptococci].

We examined the surface characteristics of four group A Streptococcus strains in log or stationary phase of growth by using the techniques of salt aggregation and of adhesion to n-hexadecane. By means of the former technique a greater correlation was observed between surface hydrophobicity and production of M protein (above all in stationary phase of bacteria). Using the latter one, we noted differences depending on the growth phase, but not related to M protein. The pretreatment of bacteria with subCMI of clindamycin decreases their hydrophobicity, particularly in M+ strains and in stationary phase of growth. Less variations of surface were observed in M- strains and after treatment with subCMI of imipenem.