1 Operative Research Unit of Geriatrics, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy.
2 Operative Research Unit of Geriatrics, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy. Electronic address: d.lelli@policlinicocampus.it.
3 Clinical Laboratory Unit, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy; Applied Bacteriological Science Unit, Department of Medicine and Surgery, Università Campus Bio-Medico, Rome, Italy.