1. Clinical Microbiology L2:02, Karolinska Institutet-MTC, Karolinska University Hospital Solna, SE-17176 Stockholm, Sweden
2. National Center for Antimicrobials and Infection Control, Statens SerumInstitut, Copenhagen, Denmark
3. Antibiotic Research Unit, Department of Medical Sciences, Clinical Bacteriology and Infectious Diseases, Uppsala University, Uppsala, Sweden
4. Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, Massachusetts
5. Division of Epidemiology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel