Identification of Strains of Streptococcus pyogenes of Types 5, 11, 12, 27 and 44 by the Precipitin Test for the T Antigen

Summary: Strains of Streptococcus pyogenes belonging to Types 5, 11,12, 27 and 44 share a minor T antigen. In addition, there are three major T antigens in this set of types, one in Type 11, one in Type 12 and the third common to Types 5, 27 and 44. T antigen, prepared by Pakula’s method, is a satisfactory fraction for absorbing the antibodies from serum, the advantage being that very little serum is lost with each absorption because the volume of T antigen required is so small. The Pakula method of extraction of the T antigen can also be satisfactorily used in routine typing. Type 11 strains can be definitely identified by the T precipitin test, and this test can also be used for identifying Type 12 strains that give no reaction with Type 12 anti-m sera. There are some strains which have agglutination patterns of the series 5, 11, 12, 27 and 44 but which give no precipitation with the T antisera. It may be that in these the major T antigen has not been recognized.