1. Institute for Food Safety and Hygiene, National Centre for Enteropathogenic Bacteria and Listeria, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.
2. Cantonal Laboratory Ticino, Division of Public Health, Department of Health, Bellinzona, Switzerland.
3. Laboratory of Bacteriology, Department of Laboratory Medicine, Ente Ospedaliero Cantonale, Bellinzona, Switzerland.
4. Office of the Chief Medical Officer of Canton Ticino, Division of Public Health, Department of Health, Bellinzona, Switzerland.