Serological grouping of hemolytic streptococci by counter-immunoelectrophoresis.

The counter-immunoelectrophoresis (CIE) method of grouping streptococci was more sensitive than the capillary precipitin method. The precipitate was easier to read, and the test was simple to perform and required fewer reagents. An autoclave-Pronase-B extraction procedure is described and was found superior to either acid, Pronase-B, or the autoclave extraction procedures for recovering groupable polysaccharide from different strains of streptococcal groups A, B, C, D, F, and E. Data obtained from over 400 strains indicate that the sensitivity of the CIE and a more efficient extraction of groupable polysaccharide provides a simple method for rapid diagnosis of streptococcal infections.