Loading...
Polymyxins — polymyxin B and polymyxin E (colistin) — are drugs of last resort in treating multidrug-resistant gram-negative infections. Previously, colistin resistance was attributed to chromosomal mutations and was not known to disseminate widely.
Prompted by an observed increase in colistin resistance in isolates from food animals in China, investigators sought the mechanism. They ultimately identified plasmid-mediated colistin resistance (MCR-1) in Escherichia coli from a pig. Upon screening isolates from five Chinese provinces, they found the mcr-1 gene in 21% of 804 E. coli isolates in pigs at slaughter; in retail meat (22% of pork and 28% of chicken isolates in 2014); and in 1% of 1322 E. coli and Klebsiella pneumoniae clinical isolat…