Dendrogram made from the AFLP fragment patterns of all the analyzed strains with their corresponding PFGE, PCR-AFLP, and AFLP profile names. Different outbreaks are numbered and are from different regions and years as follows: 1, southwest Norway, 1998; 2, north Norway, 1988; 3, Lake Mjøsa annual bicycle race, 1999; 4, north Norway, 1981; 5, lake Mjøsa annual bicycle race, 1997; 6, central Norway, 1998; 7, south Norway, 1997; 8, central Norway, 1995; 9, south Norway, 1997; 10, Finland, 1998. ND, not done.