1. Department of Infectious Diseases; Bern University Hospital and University of Bern; Bern Switzerland
2. Division of Infectious Diseases; Regional Hospital Lugano; Lugano Switzerland
3. Division of Infectious Diseases and Hospital Epidemiology; University Hospital Zurich; University of Zurich; Zurich Switzerland
4. Basel Institute for Clinical Epidemiology & Biostatistics; University Hospital Basel and University of Basel; Basel Switzerland
5. Department of Infectious Diseases & Hospital Hygiene; University Hospital Basel and University of Basel; Basel Switzerland
6. Division of Infectious Diseases; University Hospital Lausanne; University of Lausanne; Lausanne Switzerland
7. Division of Infectious Diseases; University Hospital Geneva; University of Geneva; Geneva Switzerland
8. Division of Infectious Diseases and Hospital Epidemiology; Cantonal Hospital St.Gallen; St.Gallen Switzerland
9. Institute of Social and Preventive Medicine; University of Bern; Bern Switzerland