Method for phage typing group A type 49 streptococci.

A method of phage subtyping group A type 49 streptococci is described. The method is similar to that used for phage typing staphylococci, except that lysates obtained by induction with mitomycin C rather than propagated stock phages were used. Five type 49 strains were used as phage donors. Seventy-two strains of type 49 streptococci isolated from 10 worldwide sources were examined by this method. Among these strains, five distinct subtypes (I through V) could be distinguished on the basis of their lytic patterns. Only a few of the type 49 strains could not be classified into one of these phage subtypes (6% using 100 X routine test dilution). Strains from a single source were generally homogeneous with respect to their phage subtype. The method proved useful in discriminating between type 49 strains isolated from different geographical sources and from the same place in different years. Studies in progress suggest that it may be useful for subtyping other strains of special epidemiological interest, such as strains of other serological types associated with nephritis.