1. Institute for Veterinary Bacteriology, University of Beme, 3012 Berne, Switzerland
2. Clinic of Equine Medicine, University of Beme, 3012 Berne, Switzerland
3. Institute for Microbiology, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland
4. Institute for Veterinary Pathology, University of Beme, 3012 Berne, Switzerland