1. Infectious Diseases Unit, Department of Clinical and Experimental Medicine, Azienda Ospedaliero Universitaria Pisana , University of Pisa, Pisa , Italy
2. Microbiology Unit, Azienda Ospedaliero Universitaria Pisana , Pisa , Italy
3. Department of Anaesthesia and Critical Care Medicine, Azienda Ospedaliero Universitaria Pisana , Pisa , Italy