1. Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
2. Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
3. Department of Pathology, Universidad del Valle, Cali, Colombia
4. Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer-Institute, Ludwig Maximilians University, Munich, Germany
5. Division of Gastroenterology and Irvine Cancer Research Center, Columbia University, New York, New York, USA