Integration of the blaNDM-1 carbapenemase gene into Proteus genomic island 1 (PGI1-PmPEL) in a Proteus mirabilis clinical isolate

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.