Tigecycline is considered one of the last-resort antimicrobials for carbapenem-resistant K. pneumoniae. Plasmid-mediated tigecycline resistance remains largely unclear. Here, by utilizing whole genome sequencing, we report a plasmid-mediated tigecycline resistance mechanism, a 6,489 bp Resistance-nodulation-division family (RND) efflux pump (tmexCD1-toprJ1 pump), that confers transferable tigecycline resistance in K pneumoniae isolated from patients and chickens. In addition, we identified high prevalence of the plasmids co-harbouring both tmexCD1-toprJ1 pump and mcr (tmexCD1-mcr co-harbouring plasmid) from human in...