Fig. 3

Clustering of global plasmids in Gram-negative bacteria hosts. The Neighbor-Joining tree consisting of 2749 Gram-negative plasmid sequences was constructed to reflect the gene composition similarity of the plasmids. Seven bla _NDM-positive plasmid phylogenetic clusters were identified using stringent criteria (all nodes ≥99 % bootstrap support, minimum 2 unique bla _NDM-positive plasmids). Clusters with bla _NDM-positive plasmids are indicated with dots that are colored distinctively with blue (C1), purple (C2), green (C3), magenta (C4), orange (C5), grey (C6) and red (C7)