1. Department of Epidemiology and Preventive Medicine School of Public Health Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel
2. Department of Geriatric Rehabilitation Tel Aviv Sourasky Medical Centre Tel Aviv Israel
3. Clinical Microbiology Laboratory Tel Aviv Sourasky Medical Centre Tel Aviv Israel
4. Division of Epidemiology Tel Aviv Sourasky Medical Centre Tel Aviv Israel
5. Sackler Faculty of Medicine Tel Aviv University Tel Aviv Israel