1. Department for Interventions in Health-Care Facilities, Hellenic Center for Disease Control and Prevention, Athens, Greece
2. Department of Microbiology, Medical School of National and Kapodistrian University of Athens, Athens, Greece
3. Occupational Medicine, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
4. First Department of Pediatrics, National and Kapodistrian University of Athens, Athens, Greece