Evolution of IncA/C blaCMY-2-carrying plasmids by acquisition of the blaNDM-1 carbapenemase gene

The blaNDM-1 gene has been reported to be often located on broad-host-range plasmids of the IncA/C type in clinical but also environmental bacteria recovered from the New Delhi, India, area. IncA/C-type plasmids are the main vehicles for the spread of the cephalosporinase gene blaCMY-2, frequently identified in the United States, Canada, and Europe. In this study, we completed the sequence of IncA/C plasmid pNDM-KN carrying the bla NDM-1 gene, recovered from a Klebsiella pneumoniae isolate from Kenya. This sequence was compared with those of three IncA/C-type reference plasmids from Escherichia coli, Yersinia ruckeri, and Photobacterium damselae. Comparative analysis showed that the blaNDM-1 gene was located on a widely diffused plasmid scaffold known to be responsible for the spread of blaCMY-2-like genes and consequently for resistance to broad-spectrum cephalosporins. Considering that IncA/C plasmids possess a broad host range, this scaffold might support a large-scale diffusion of the blaNDM-1 gene among Gram-negative rods. Copyright © 2012, American Society for Microbiology. All Rights Reserved.