1. Department of Medicine, Baylor College of Medicine, and Bacterial Enteropathogens Laboratory, Gastroenterology Section,
Veterans Affairs Medical Center, Houston, Texas,
2. Laboratory of Research in Bacteriology, Universidade Federal de Minas Gerais,
Belo Horizonte, Brazil
3. Department of Medical Microbiology and Immunology, University of Göteborg, Göteborg, Sweden