aDepartment of Pulmonology, University of Udine and Azienda Sanitaria Universitaria Integrata di Udine, Udine

bDepartment of Health Sciences (DISSAL), University of Genoa

cClinica Malattie Infettive, IRCCS San Martino polyclinic Hospital, Genoa, Italy

Correspondence to Dr Antonio Vena, Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy; Infectious Diseases Unit, San Martino Policlinico Hospital, IRCCS for Oncology and Neuroscience, Largo Rosanna Benzi, 10, 16132 Genova, GE, Italy. Tel: +39 010 5554658; fax: +39 010 5554658; e-mail: [email protected]