Genome alignment of E. coli O104:H4 isolates highlighting mobile genetic elements and variable regions. The chromosomal sequences of E. coli O104:H4 isolates 55989 (17), Ec04-8351, Ec09-7901, Ec11-9450, Ec11-9941, Ec11-9990, Ec12-0465, Ec12-0466, and TY2482 (14) were aligned by progressiveMauve (45). The background color gradient indicates homologous regions across strains. Prophage predicted by PHAST (48) are designated by rectangles and labeled based on similarity of encoded phage gene content. Genomic islands are designated by black bars. Gray blocks between genomes denote homologous regions at least 5 kb in size. Phylogenetic reconstruction was based on the maximum likelihood method using core SNPs predicted from the progressiveMauve genome alignments and supported by 500 bootstraps.