1 Microbiology Unit, S. Donato Hospital, Arezzo, Italy.
2 Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy; Microbiology and Virology Unit, Careggi University Hospital, Florence, Italy. Electronic address: alberto.antonelli@unifi.it.
3 Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy; Microbiology and Virology Unit, Careggi University Hospital, Florence, Italy.