Fig. 3

Phylogenetic tree of PBP amino acid sequences and β-lactam resistance phenotype comparison of groups in CC271. a, b Phylogeny of PBP2b (a) and PBP2x (b) amino acid sequences of 526 CC271 isolates. Bolded branches with colors are the manually selected representative sequences that correspond to each group and are identical or less different, and a few black branches that are not bolded represent PBP sequences with distinct variation that may be due to additional recombination and are not focused here. PBP2b sequence of Taiwan19F-14 (marked in figure) reference genome is similar but different from those of 19F ST236 isolates in our sample. All 19F ST271-A isolates had 100% identical PBP2b sequences with two 19F ST236 isolates in our sample. PBP2b sequences of 19F ST320 and most 19A ST320 were 100% identical. PBP2x sequences of most 19F ST236 and 19F ST271-A were 100% identical. c MICs of each β-lactam antibiotic in each group. The X-axis corresponds to each group, and the Y-axis corresponds to the log2(MIC) value. The presence of a significant difference between the two groups is marked in the figure, respectively. *p < 0.05. **p < 0.01. ***p < 0.001. ****p < 0.0001, ns, not significant