eBURST analysis of porcine extraintestinal Escherichia coli. Clonal structure of ExPEC is demonstrated by eBURST plot based on the profile of seven allelic housekeeping genes. Strains share five of seven alleles was grouped into a clonal complex. Porcine pathogenic ExPEC strains comprised four main CCs (a: clonal complex 10, b: clonal complex 1687, c: clonal complex 88, and d: clonal complex 58), two doublets and 9 singletons. E. coli strains from the same ancestor based on the whole MLST data were grouped together with black circles. The ancestral ST is denoted in blue and the derived and ungrouped STs are in black. Individual strains responsible for SLVs and DLVs among these CCs are connected to their ancestral ST with the black and purple lines, respectively.