1. Institute of Hospital Hygiene, City of Cologne Hospitals, Cologne, Germany
2. National Reference Centre for Staphylococci and Enterococci, Division 13: Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
3. Labor im Sommershof, Praxis für Laboratoriumsmedizin Dr. med. Christiane Boogen, Cologne, Germany
4. Department of Internal Medicine, City of Cologne Hospitals, Cologne, Germany