Analysis of PTUs (as in Fig. 2), but where the PTU AMR+ were purged from antibiotic resistance plasmids. Left panel: schema describing dataset filtering and number of PTUs in the final dataset. Right panels: distribution of the values of mean nRF a), beta b), mean wGRR c), and IS density d) between AMR− and AMR+ PTUs (excluding the antibiotic resistance plasmids). Boxplots are presented as in Fig. 1. Statistical significance (Mann–Whitney U): *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001.