To the investigators knowledge no randomized, placebo-controlled clinical trial has been performed to study the efficacy of a systematic ESBL eradication strategy. Eradication of ESBL carriage would cause benefits for the individual patient - by reducing the risk of infection - and for the community - by reducing transmission. Even if eradication turns out to be impossible, transient suppression of ESBL might reduce the likelihood of transmission and thus still be beneficial from an ecologic perspective.