1. National Reference Center for Salmonellae and Other Enteric Pathogens, Robert Koch-Institut, D-38855 Wernigerode, Germany
2. Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University System Health Science Center, College Station, Texas 77843-1114
3. and Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843-4467