Resistance to Antibiotic of Last Resort Found in Salmonella

As the antibiotic resistance crisis worsens, the emergence of new antibiotic resistance genes is worrisome, even if it may no longer be surprising. The recently reported identification of mcr-9, a novel gene conferring resistance to the antibiotic colistin, raises unique concerns as colistin is one of the world’s few last-resort antibiotics.

The newly discovered gene, mcr-9, discovered by food scientists at Cornell University in Ithaca, New York, belongs to a class of plasmid-borne genes that confer resistance to colistin. To date, eight known mcr homologues have been described (mcr-1 to -8.)