Field inversion gel electrophoresis as a typing system for group A streptococcus.

Field inversion gel electrophoresis (FIGE) was performed on 139 isolates of group A streptococcus (GAS) representing 72 different M types. Multiple isolates were tested for 27 M types (range, 2-19). Each of the M types tested had at least one unique banding pattern that was not observed in any other M type. For 23 of 27 M types for which multiple isolates were available, band profiles of the isolates were the same or differed by < 3 bands and are considered indistinguishable or closely related. These data demonstrate that FIGE of the DNA of GAS identifies differences between and within M types.