Abdul Ghafur explains how the team deciphered the mechanism by which Klebsiella bacteria develop resistance to colistin, a last-line antibiotic. Mutations and insertional inactivation of the mgrB gene, which is present in the chromosome, are responsible for colistin resistance in Klebsiella. The inserational sequence that moves out from the chromosome to plasmid before spreading to other bacteria helps colistin resistance to spread.