Pseudomonas putida group species serve as reservoirs of conjugative plasmids disseminating Tn402-like class 1 integrons carrying blaVIM-2 metallo-β-lactamase genes

The Pseudomonas putida group ( P. putida G) is composed of at least 21 species associated to a wide range of environments, including the clinical setting. Here, we characterized 13 carbapenem-resistant P. putida G clinical isolates carrying bla VIM-2 from different hospitals of Argentina. Multilocus sequencing (MLSA) and phylogenetic analyses based on the 16S rDNA, gyrB and rpoD sequences comparison allowed us to assign them to 7 well-differentiated species. Sequencing analysis revealed that bla VIM-2 genes were carried in these isolates by three different class 1 integrons (In 41 , In 899 and In 528 ) embedded into Tn 402 -like transposons. Those harboring In 41 and In 899 were designated Tn 6335 and Tn 6336 , respectively, with the former found among 10 isolates. Both encompassed complete transposition modules and inverted repeats boundaries characteristic of the Tn 5053 /Tn 402 family, whereas the third, bearing In 528 , exhibited a defective tni module. Tn 6335 and Tn 6336 were located in conjugative pLD209-type plasmids in P. asiatica, P. juntendi, P. putida G/II, and P. putida G/V isolates, and could be mobilized to Escherichia coli and P. aeruginosa indicating a relevant mechanism of bla VIM-2 dissemination. In other P. asiatica and P. putida G/II isolates, Tn 6335 was found inserted into the Tn 21 subgroup transposons- res region, indicating capability for intragenomic mobilization and further dissemination associated to Tn 3 family transposons. The Tn 402 -like defective element was also found inserted into the res region of another Tn 3 family transposon in a P. monteilii isolate, but in an atypical orientation. Overall findings shed light on the mechanisms by which resistance genes move through environmental and opportunist Pseudomonas species.