1. Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06123 Perugia, Italy
2. Clinic of Infectious Diseases, “Santa Maria” Hospital, Terni, 05100 Terni, Italy
3. Department of Medicine and Surgery, Medical Microbiology Section, University of Perugia, 06123 Perugia, Italy