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

Abstract

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 blaVIM-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 blaVIM-2 and tmexCD1-toprJ1 genes. The gene blaVIM-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 blaVIM-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.