Distinct mechanisms of dissemination of NDM-1 metallo- β-lactamase in Acinetobacter spp. in Argentina.

A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying bla(NDM-1). Genome sequencing revealed that most were Acinetobacter baumannii, whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. bla(NDM-1) was located in the chromosome of A. baumannii strains and on a plasmid in non-A. baumannii strains. A resistance gene island carrying bla(PER-7) and other resistance determinants was found on a plasmid in some A. baumannii strains.