Fig. 2

Genetic relationship between the isolates. (a) Minimum spanning tree of all investigated isolated, coloured by their sequence type (ST). The size of the nodes is proportional to the number of isolates represented by the respective node, as is the length of the branches to the number of allelic differences. Thirteen clusters (I-XIII) were gathered, adhering to a threshold of 4 or more matching alleles in MLST profiling. (b) Topological representation of genetic relationships of the investigated isolates. Sequence types are coded in the same colours as in (a). The branch lengths are relative and not to scale. Isolate IDs consist of the horse ID, followed by “P” for pastern samples or “N” for nasal samples. Isolates from control horses are written in italics. Methicillin-resistant strains are marked by an asterisk (*). Closely related isolates originating from the same horse are displayed with a black background