Colistin is a polymyxin antibiotic effective against several pathogenic species of Gram-negative bacteria, including Pseudomonas, Klebsiella and E. coli. Even though the drug can cause kidney damage, it is still in use due to its role as a “drug of last resort” for certain bacterial infections. A new report in The Lancet details extensive spreading of colistin-resistant E. coli in China. The spread of resistance is thought to be due to plasmid-based sharing of a colistin-resistance mechanism caused by the overuse of colistin in pig farms. The resistant stain is also appearing commonly in the human population in southern China.