The Serological Typing of Hemolytic Streptococci

The relationships among the hemolytic streptococci have been greatly clarified by the fundamental work of Lancefield (1). She has shown that these organisms may be classified into groups on the basis of a precipitin reaction and ample evidence has accumulated (2, 3) to show that almost all human infections are caused by members of her Group A. Strains of the groups from B to K are responsible for many types of infection in animals, and occasionally in man, and are also frequent normal inhabitants of the human nose, throat and bowel. Non-hemolytic varieties are also well known among these groups (4). The strains which are members of Group A may be further classified into more than 30 types by an agglutination test as described by Griffith (5). Many technical difficulties have prevented the widespread application of this procedure but the modifications of the original method suggested by Ward and Rudd (6) and further revised in this laboratory have made the serological typing of these streptococci simple and reliable. The development of a satisfactory method of classifying the hemolytic streptococci pathogenic for man into types has offered a tool for the investigation of many aspects of the epidemiology, nature, and therapy of infections due to these organisms. Except for studies of epidemiology and observations on the relation of type to immunity, practically no answers have yet been obtained to the challenging questions which the availability of this method has raised. A continuing study of hemolytic streptococcal infection in the San Francisco area has, therefore, been undertaken, and the Griffith classification has been applied for the purpose of gaining further information on the relationship of the serological types of Group A to disease states. It is the purpose of this paper to review the published data bearing on this subject, to present certain modifications of method which increase the simplicity and reliability of the serological typing of the hemolytic streptococci and to state and discuss the results of the application of these methods to strains of streptococci isolated from infections and from normal human subjects in San Francisco during the seasons of 1940 and 1941.