1 Infectious Diseases Unit, Internal Medicine Department, University Hospital Puerta de Hierro-Majadahonda, Health Research Institute Puerta de Hierro-Segovia de Arana, 28222 Majadahonda, Spain.
2 First Department of Critical Care Medicine and Pulmonary Services, Evangelismos Hospital, National and Kapodistrian University of Athens Medical School, 11527 Athens, Greece.