COMPARISON OF ORAL STREPTOCOCCUS-MUTANS AHT WITH STRAINS OF SEROTYPE-A AND SEROTYPE-G BY BIOCHEMICAL AND ELECTROPHORETIC METHODS

Streptococcus mutans strain AHT was placed by Bratthall in serotype a, but several laboratories reported the existence of subcultures of AHT which have the serotype g antigen. To investigate the possibility that the a polysaccharide antigen of the aberrant AHT stocks had undergone antigenic shift to type g, five stock cultures of AHT were obtained from different sources and compared with other strains of serotypes a and g by serological, biochemical and electrophoretic techniques. The AHT cultures were either a- or g-like in all characters tested. Two strains were type a and three type g. There is therefore no evidence for an alteration of serotype antigen independent of other characters of serotype a. Some laboratories must hold cultures not truly representative of Strep, mutans AHT. © 1979.