1Atlanta Research and Education Foundation, Decatur, Georgia.
2Division of Foodborne, Bacterial, and Mycotic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
3Department of Infectious, Parasitic and Immune-Mediated Diseases Istituto Superiore di Sanità, Rome, Italy
4Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, Maryland.