Acquisition and diffusion of blaCTX-M-9 gene by R478-IncHI2 derivative plasmids

Escherichia coli and Salmonella enterica isolates carrying the bla CTX-M-9 gene located on plasmids prevailed at the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain in the 1996-1999 period. The bla CTX-M-9-carrying plasmids showed a great variability in size, suggesting the mobilization of the gene among different plasmid scaffolds. The aim of the present work was to identify and better characterize the plasmids involved in the spread of the blaCTX-M-9 gene. Results showed that the majority of these strains carried plasmids belonging to the IncHI2 incompatibility group. The IncHI2 plasmids were further characterized, and found to be related to the reference IncHI2 plasmid R478. © 2007 Federation of European Microbiological Societies