Comparative genome analysis of IncHI2 VIM-1 carbapenemase-encoding plasmids of Escherichia coli and Salmonella enterica isolated from a livestock farm in Germany.

Carbapenem-resistant Enterobacteriaceae are not any more isolated only from human settings, but also from livestock. We reported for the first time the presence of VIM-1 carbapenemases in a livestock farm in Germany. The VIM-1 resistance gene found in these farms was located on IncHI2 plasmids. In order to be able to analyse these plasmids in more detail, two different plasmids from a single farm (pRH-R27 from Salmonella enterica and pRH-R178 from Escherichia coli) were completely sequenced and analysed for the presence of antibiotic and heavy metal resistances. The plasmids showed to harbour blaVIM-1, aacA4, aadA1, sul1, qacEΔ (encoded in an In110 class 1 integron), as well as blaACC-1, strA/strB, and catA1 genes together with resistance to heavy metals (ter-, mer-, sil-, ars-, rcn-, and pco). Comparison with other IncHI2 plasmid revealed that while pRH-R27 is a mosaic IncHI2 plasmid with both high homology to the plasmid pSTm-A54650 and R478, both isolated from humans, pRH-R178 is a deletion derivative of pRH-R27, presumably caused by several IS-mediated deletions indicating genetic evolution of plasmids in this environment.