Characterization of TMexCD3-TOprJ3, an RND-type efflux system conferring resistance to tigecycline in Proteus mirabilis, and its associated Integrative Conjugative Element.

The emergence and transmission of novel antimicrobial resistance genes pose a great threat to public health globally. Recently, the plasmid-encoding RND efflux pump TMexCD1-TOprJ1 in Klebsiella pneumoniae was reported to reduce the sensitivity of multiple antimicrobials. Herein, we identified a pandrug-resistant Proteus mirabilis isolate, which harbored the novel tmexCD3-toprJ3 gene cluster located on SXT/R391 ICE. This study expands current knowledge in transfer mechanism of tmexCD1-toprJ1-like gene clusters among P. mirabilis and warrant further genomic epidemiology investigations.