1. Department of Internal Medicine, School of Medicine, University of Catania, Catania, Italy,
2. Department of Biomedical Sciences, School of Medicine, University of Catania, Catania, Italy
3. Department of Internal Medicine, School of Medicine, University of Catania, Catania, Italy
4. Department of Biomedical Sciences, School of Medicine, University of Catania, Catania, Italy, Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA