Objectives: To decipher the mechanisms and their associated genetic determinants responsible for β-lactam resistance in a Proteus mirabilis clinical isolate.
Methods: The entire genetic structure surrounding the β-lactam resistance genes was characterized by PCR, gene walking and DNA sequencing.
Results: Genes encoding the carbapenemase NDM-1 and the ESBL VEB-6 were located in a 38.5 kb MDR structure, which itself was inserted into a new variant of the Proteus genomic island 1 (PGI1). This new PGI1-PmPEL variant of 64.4 kb was chromosomally located, as an external circular form in the P. mirabilis isolate, suggesting potential mobility.
Conclusions: This is the first known description of the bla(NDM-1) gene in a genomic island structure, which might further enhance the spread of the bla(NDM-1) carbapenemase gene among enteric pathogens.
Keywords: NDM-1; P. mirabilis; VEB-6; carbapenem resistance; genomic island SGI1.
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