The emergence and global dissemination of carbapenemases represents a major threat to public health. Switzerland has not been spared; we report a case-series of four patients hospitalised in our institution colonised with carbapenemase-producing bacteria. Infections caused by carbapenemase-producing Enterobacteriaceae limit therapeutic options and increase mortality. Detection of carbapenemases is also a challenge for laboratories. It is imperative to implement stringent infection control measures in order to prevent epidemics at the hospital level.