Neighbor joining tree of 16S rRNA gene sequences (1310 bp) of 47 Yersinia strains. Bootstrap confidence values over 75% (1000 replicates) are given in the branches. sr = serum resistance, pt = phage type, which encodes reaction to 5 phages (φR1–37, PY100, φYeO3–1, φR1-RT, φ80–81). Strains sequenced in the present study are marked bold. Strain ATCC9610 is a type strain of Y. enterocolitica ssp. enterocolitica.