Figure A1. Genetic relationships among 660 Listeria monocytogenes isolates. The graph is a minimum spanning tree based on allelic profiles by using BioNumerics version 6.1 (Applied-Maths, Sint-Martens-Latem, Belgium). The 300 isolates of this study are in blue; the 360 L. monocytogenes isolates and reference strains of our earlier study (12) are in white and gray, respectively. Each circle represents a multilocus sequence typing genotype (ST), the size of which is related to the number of isolates (see legend). Clones, defined as clonal complexes [CC], are composed of groups of STs linked with a single gene difference, denoted as bold lines (see legend); clone number is indicated for the major clones. Links with >2 mismatches are unreliable because many alternatives may exist; links with 7 mismatches are not shown.