Identification of a New Delhi metallo-β-lactamase-4 (NDM-4)-producing Escherichia coli in Italy

Background: During June-July 2012, six imipenem-resistant Escherichia coli isolates were isolated from two patients hospitalized in a ward of one large tertiary-care hospital in Genoa, Italy. Genetic features associated with bla(NDM-4) gene were investigated. Results: The isolates exhibited the same PFGE profile and a multidrug-resistant (MDR) phenotype to aminoglycosides, fluoroquinolones, and beta-lactams. The strains produced the NDM-4 carbapenemase and the bla(NDM-4) gene was part of the variable region of a class 1 integron. MLST analysis revealed that all isolates belonged to sequence type 405 (ST405). Conclusions: This is the first report on the emergence of an MDR strain of E. coli producing the NDM-4 MBL in Italy.