Default model parameters of the model.

*“Colonization pressure”, i.e. the frequency of both asymptomatic and symptomatic carriers in a hospital ward has been shown to be a major risk factor for the acquisition of a nosocomial pathogen [26]. It also has been shown for clostridium difficile, that environmental contamination occurred for both symptomatic and asymptomatic infections [27]. Nevertheless, it is conceivable that e.g. in symptomatically infected patients with diarrhea infectivity is much higher than in asymptomatic patients. However, since the connection between carriage and infection is established and data on potential differences in infectivity between symptomatic and asymptomatic patients are scarce, we chose not to distinguish between these two classes.**The average length of stay is 8 days in Switzerland (http://www.obsandaten.ch/indikatoren/5_4_1/2005/d/541.pdf, data from 2005) and 5 days in the US (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5427a6.htm).***cE is an arbitrary. However, in order to make the environment comparable with direct transmission, the transmission rate βE from the environment is adjusted depending on the decay and colonization rates, such that the R0 remains constant.