1. University of Zurich, Institute of Medical Microbiology, Gloriastrasse 30/32, CH-8006 Zurich, Switzerland
2. Division of Internal Medicine, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland
3. Division of Infectious Diseases and Hospital Epidemiology, University of Zurich, University Hospital of Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland
4. Division of Infectious Diseases and Hospital Hygiene, Department of Internal Medicine, Stadtspital Triemli, CH-8063 Zurich, Switzerland
5. Department of Internal Medicine, Kantonsspital Winterthur, CH-8401 Winterthur, Switzerland