Polyclonal carbapenemase-producing Escherichia coli in Northern Italy: the emergence of NDM-7

The spread of extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing <i>Escherichia coli</i> clones in humans, animals, and the environment is of great concern worldwide. In this study, we characterized four carbapenemase-producing <i>E. coli</i> (CP-Ec) isolated from human samples. Two isolates of ST401, rarely associated with carbapenemase and/or ESBL resistance genes, harbored <i>bla</i>KPC-3 and <i>bla</i>VIM-1 genes, respectively, and were genetically distant from each other. One CP-Ec isolate belonging to ST355, typically found in poultry and environmental sources and not associated with carbapenemases, was <i>bla</i>KPC-3 positive and showed a wide range of virulence genes. The last CP-Ec strain belonged to ST3564, previously described in livestock with a large virulome but no carbapenemase. The CP-Ec ST3564 isolate co-harbored <i>bla</i>VIM-1 and <i>bla</i>NDM-7 genes, which, to our knowledge, have not been previously reported in Italy. These results emphasize the crucial role of a genomic-based surveillance program to intercept the emergence of critical <i>E. coli</i> clones.