1. Department of Digestive Diseases, General University Hospital Gregorio Marañón, Dr. Esquerdo 46, 28007 Madrid, Spain
2. CIBER Hepatic and Digestive Diseases (CIBEREHD), 07110 Bunyola, Balearic Islands, Spain
3. Department of Clinical Microbiology and Infectious Diseases, General University Hospital Gregorio Marañón, Dr. Esquerdo 46, 28007 Madrid, Spain
4. CIBER Respiratory Diseases (CIBERES CB06/06/0058), 07110 Bunyola, Balearic Islands, Spain
5. Department of Medicine, Faculty of Medicine, Complutense University of Madrid, 28040 Madrid, Spain
6. Spanish Study Group on Infection in Transplant Recipients (GESITRA-RESITRA-REIPI), RD06/0008/1025, Spain