Real-time PCR for detection of plasmid-mediated polymyxin resistance (mcr-1) from cultured bacteria and stools.

OBJECTIVES The aim of the study was to develop a simple assay for rapid detection of the mcr-1 gene, recently identified as a source of plasmid-mediated acquired resistance to polymyxins in Enterobacteriaceae. METHODS A SYBR Green-based real-time PCR assay was designed for detection of the mcr-1 gene. This assay was applied to cultured bacteria and to spiked human and cattle stools. RESULTS The mcr-1 gene could be detected with a lower limit of 10(2) cultured bacteria. This test was highly sensitive and specific, and generated no false-positive results. The assay was also conclusive when applied to stools spiked with mcr-1-positive Escherichia coli. CONCLUSIONS This simple, rapid, sensitive and specific assay will be useful for rapid screening of this resistance trait in both human medicine and veterinary medicine.