1. Institute of Medical Microbiology, Canton Hospital Luzern, Switzerland
2. Medical Department I, University Hospital Dresden, Germany
3. Institute of Medical Microbiology and Hygiene, Technical University Dresden, Germany
4. Laboratory of Food Microbiology, Institute of Food Science and Nutrition, Swiss Federal Institute of Technology Zurich, ETH Center LFV B21, Schmelzbergstrasse 7, CH-8092 Zurich, Switzerland