Detection of plasmid-mediated colistin-resistant and carbapenem-resistant genes by multiplex PCR.

A multiplex PCR was described to simultaneously detect mcr-1 and frequently occurring carbapenem-resistant genes including bla KPC , bla NDM , bla IMP , and bla OXA-48-like in a single reaction. The PCR product sizes of these 4 carbapenem-resistant genes were 232 bp, 438 bp, 621 bp, and 798 bp for bla IMP , bla OXA-48-like , bla NDM , and bla KPC , respectively, whereas mcr-1 revealed 1126 bp of PCR product. This protocol accurately detected those resistant genes in agreement with the reference strains, 127 local carbapenem-resistant Enterobacteriaceae, 8 mcr-1 carrying Enterobacteriaceae, and 62 carbapenem-susceptible Enterobacteriaceae. This method will be useful for laboratory application and surveillance of carbapenem and/or colistin-resistant bacteria.