Prevalence of the colistin resistance gene mcr-1 in colistin-resistant Escherichia coli and Klebsiella pneumoniae isolated from humans in Thailand.

Objectives: Historically, colistin has been considered a last-line therapeutic option against multidrug-resistant Gram-negative bacterial infections. However, chromosomally-encoded and plasmid-mediated colistin resistance is increasingly being reported worldwide. Spread of the plasmid-borne colistin resistance gene mcr-1 is of great concern since it can be transferred between bacteria.