1. Center for Food Safety and Applied Nutrition, Division of Microbiology, Office of Regulatory Science, U.S. Food and Drug Administration, College Park, Maryland, USA
2. New England BioLabs, Inc., Ipswich, Massachusetts, USA
3. EU Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy