The genetic diversity indexes for the genes used in MLST were 0.86 (adk), 0.93 (argA), 0.93 (aroA), 0.83 (glnA), 0.82 (gyrB), 0.94 (thrA) and 0.89 (trpE). Bayesian analysis of the MLST sequences divided the BT 1A strains into two distinct genetic clusters, which were clearly separated from the tight cluster formed by the strains of BT’s 2–4 and from

the BT 1B strain (8018) (Figure 1). One of the BT 1A clusters contained 36 BT 1A and two non-biotypeable strains and was designated as BT 1A Genetic group 1. Another cluster contained five BT 1A strains and was designated as BT 1A Genetic group 2. Ten bio/serotype 3-4/O:3 and 2/O:9 strains clustered closely AMN-107 datasheet together, and the single BT 1B strain was located in the vicinity of this cluster. BAPS analysis did not indicate any significant level of mosaicism AZD1152 among the isolates, i.e. no isolates contained variation typical to more than one cluster. Figure 1 Maximum likelihood tree based on the MLST of seven house-keeping genes of Y. enterocolitica strains. Color-coding indicates the BAPS groups. The BT 1A strains were divided into two clusters indicated in blue (Genetic group 1) and yellow

(Genetic group 2). Strains of BT’s 2–4 are indicated in red and the BT 1B strain in green. When concatenated MLST sequences (4580 bp) were compared to each other, the BT 1A Genetic group 2 strains were 95–96% similar to BT 1A Genetic group 1, bio/serotype 4/O:3 and 2/O:9, as well as to Y. enterocolitica ssp. enterocolitica strains of biotype

1B (Table 1). The BT 1A Genetic group 1 strains were 97% similar to bio/serotype 4/O:3 and 2/O:9 and Y. enterocolitica ssp. enterocolitica strains (Table 1). A neighbour-joining tree depicting the relatedness of the selected Yersinia strains and species based on the MLST sequence concatenates is shown in an additional file (Additional file 1). Table 1 Genetic similarity of concatenated seven-gene MLST sequences (4580 bp)   BT 1A group1 BT 1A group2 BT 2–4 O:3/O:9 BT 1B 8081 Y. kristensenii Y. frederiksenii Y. aldovae Y. rohdei Y. intermedia Y. bercovieri Y. beta-catenin inhibitor mollaretii Y. ruckeri BT 1A Genetic group1 > 99%                       BT 1A Genetic group2 95–96% > 99%                     Teicoplanin BT 2–4 O:3/O:9 97% 95% > 99%                   BT 1B 8081 97% 95% 98% 100%                 Y. kristensenii ATCC 33638 90% 90% 90% 90% 100%               Y. frederiksenii ATCC 33641 87% 87% 87% 87% 86% 100%             Y. aldovae ATCC 35236 87% 87% 87% 87% 87% 85% 100%           Y. rohdei ATCC 43380 86% 86% 86% 86% 85% 86% 84% 100%         Y. intermedia ATCC 29909 85% 85% 85% 85% 86% 86% 86% 84% 100%       Y. bercovieri ATCC 43970 85% 85% 85% 85% 86% 85% 85% 79% 85% 100%     Y. mollaretii ATCC 43969 86% 86% 86% 86% 86% 86% 85% 79% 85% 91% 100%   Y.