Comparison of PFGE profiles from 97 human
O157:H7 isolates. PFGE profile comparison performed using UPGMA cluster analysis, Dice similarity coefficient, and 1% band matching tolerance. stx1, stx2a/c, stx2c virulence genes encoding for Shiga toxins present (1) or absent (0). Island of residence (Origin) presented as North Island (NI) or South Island (SI) of New Zealand, and genotypes of isolates as Shiga toxin (Stx)-encoding bacteriophage insertion (SBI) types.