The emergence of CPE (and carbapenem-resistance in other Gram-negative bacteria) has forced us to reach to the dusty old antibiotic shelf to revive the clinical use of older agents with activity against Gram-negative bacteria, principally colistin. Colistin isn’t perfect by any means – it has poor tissue penetration compared with the carbapenems, and is associated with nephrotoxicity (although the high levels of nephrotoxicity in the older medical literature has not been reported due to better management of the drug). Furthermore, resistance has already been reported. To date – this has been mutational resistance, which does not have the capacity to spread horizontally. It was only a matter of time before a colistin resistance gene mobilised.