The Clean Mouse Facility (CMF) is a core-facility of the Department for BioMedical Research (DBMR) of the University of Bern co-founded by the Inselspital. The CMF is a state-of-the-art gnotobiotic mouse facility that breeds and holds mice under strict axenic or gnotobiotic (defined microbial colonization) conditions. Moreover, the CMF is equipped to perform experiments under such hygienic circumstances.