Emergence of a multidrug resistance efflux pump with carbapenem resistance gene blaVIM-2 in a Pseudomonas putida megaplasmid of migratory bird origin

Background: Tigecycline and carbapenems are regarded as vital antimicrobials to treat serious bacterial infections. Co-occurrence of resistance genes conferring resistance to both tigecycline and carbapenems in Pseudomonas spp. was not investigated. Objectives: To characterize a megaplasmid co-harbouring tmexCD1-toprJ1 and bla(VIM-2) in Pseudomonas putida of migratory bird origin. Methods: One tigecycline- and carbapenem-resistant strain was isolated and characterized by antimicrobial susceptibility testing, conjugation assay, WGS and bioinformatics analysis. Results: The strain P. putida ZXPA-20 resistant to meropenem and tigecycline was positive for bla(VIM-2) and tmexCD1-toprJ1 genes. The gene bla(VIM-2) was inserted into the backbone of the megaplasmid pZXPA-20 within a Tn5090-like structure. The genetic context of tmexCD1-toprJ1 in the megaplasmid was identical to many chromosomal tmexCD1-toprJ1 of Pseudomonas species. Plasmid-mediated tmexCD1-toprJ1 gene cluster in Pseudomonas spp. was more common than that in Klebsiella pneumoniae. To the best of our knowledge, this is the first report of co-occurrence of bla(VIM-2) and tmexCD1-toprJ1 in one plasmid. Conclusions: Emergence of plasmid-mediated carbapenem and tigecycline resistance genes in P. putida from migratory birds highlighted the importance of surveillance of novel mobile resistance genes in migratory birds, which may play a vital role in global transmission of novel resistance genes.

Automated summary

This study provides the first report of co-occurrence of bla(VIM-2) and tmexCD1-toprJ1 in one plasmid in P. putida. The emergence of plasmid-mediated carbapenem and tigecycline resistance genes in P. putida from migratory birds highlights the importance of surveillance of novel mobile resistance genes in migratory birds.