1. Microbiology, Department of Clinical Sciences, School of Medicine, University of Las Palmas de G.C., Dr. Pasteur, 35080-Las Palmas G.C., Spain.
2. Department of Science and Technology, School of Medicine, University of L'Aquila, L'Aquila, Italy.
3. Department of Microbiology, Hospital Clínic, IDIBAPS, School of Medicine, University of Barcelona. 08036 Barcelona, Spain.