Plasmid-borne colistin resistance gene mcr-3 in Salmonella isolates from human infections, Denmark, 2009–17

This report describes one Salmonella isolate harbouring both mcr-1 and mcr-3. We also found nine other Salmonella isolates positive for the plasmid-borne colistin resistance gene, mcr-3. The strains were isolated from patients in Denmark between 2009 and 2017 and five of the patients had travelled to Asia. In addition to mcr-3, all strains were found positive for blaTEM-1 , strA, strB, sul2 and tet(A) or tet(B), and most strains were positive for blaCTX-M-55 and qnrS.