1. Division of Infectious Diseases and Hospital Epidemiology, University and University Hospital Zurich, Zurich, Switzerland
2. Institute of Clinical Pathology, University and University Hospital Zurich, Zurich, Switzerland
3. Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
4. Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland