Minimum-spanning tree of MLVA. Each MLVA type is indicated by one node or branch tip, displayed as circles that are connected by branches of minimum-spanning tree. A two-letter code within each circle uniquely identifies each MLVA type, which is coded in a combination of the first letter ("A" or "B") and the second letter (any of alphabetical "A-Z" or a numerical "1–9 "). Clonal complexes were created based on maximum neighbor distance of changes at two loci and minimum size of two types. The length of the branches represents genetic distances (changes in loci) between two neighboring types. The sizes of the different color-circles depend on their population size. Wedges in circles indicate the proportion of isolates from respective sources with a particular MLVA type. In case of equivalent solutions in terms of calculated distance, the highest number of single locus variants (SLVs; in case two types have an equal distance to a linkage position in the tree, the type that has the highest number of SLVs is linked first) associated was used as the priority rule for linking types in the tree.