1. Department of Biomedical Sciences amd Technologies, University of L'Aquila, Loc. Coppito, 67100, L'Aquila, Italy
2. Institute of Microbiology, University of Catania, Italy
3. Department of Clinical Sciences, University of Gran Canaria, Las Palmas, Gran Canaria, Spain
4. Medical Department of Wyeth-Lederle, Roma, Italy