1. Department of Infectious Diseases, Hospital Universitario Ramon y Cajal, Instituto de Investigación Ramón y Cajal; Universidad de Alcalá; Madrid Spain
2. Unit of Biostatistics, Ramón y Cajal Hospital, Centro de Investigación Biomédica en Red Epidemiología y Salud Pùblica; Madrid Spain
3. Unit of Infectious Diseases, Hospital Universitario Cruces; Barakaldo-Bilbao Spain
4. Department of Infectious Diseases; Hospital Universitari Vall d´Hebron
5. Department of Infectious Diseases; Hospital Universitario Reina Sofía-IMIBIC (Instituto Maimónides de Investigación Biomédica de Córdoba)-Universidad de Córdoba; Córdoba Spain
6. Department of Infectious Diseases, Hospital Universitari de Bellvitge-IDIBELL; University of Barcelona; Barcelona Spain
7. Department of Clinical Microbiology and Infectious Diseases; Hospital General Universitario Gregorio Marañón; Madrid Spain
8. Unit of Infectious Diseases, Hospital Universitario Marqués de Valdecilla, Universidad de Cantabria; Santander Spain
9. Department of Infectious Diseases, Hospital Universitari Clinic, Barcelona; Universidad Autónoma; Barcelona Spain
10. Department of Digestive Diseases; Hospital Universitario Marqués de Valdecilla; Santander Spain
11. Unit of Infectious Diseases, Hospital Universitario “12 de Octubre,” Instituto de Investigación Hospital “12 de Octubre,”; Madrid Spain