[1] Univ Hosp, Inst Environm Med, D-79106 Freiburg, Germany
[2] Univ Hosp, Hosp Epidemiol, D-79106 Freiburg, Germany
[3] Univ Hosp, Dept Med 1, Univ Med Ctr, D-79106 Freiburg, Germany
[4] Charite, Inst Hyg & Environm Med, Berlin, Germany
[5] Hannover Med Sch, Dept Med Microbiol, D-3000 Hannover, Germany
[6] Hannover Med Sch, Hosp Epidemiol, D-3000 Hannover, Germany
[7] Natl Reference Ctr Surveillance Nosocomial Infect, Berlin, Germany
[8] Natl Reference Ctr Surveillance Nosocomial Infect, Hannover, Germany
[9] Natl Reference Ctr Surveillance Nosocomial Infect, Freiburg, Germany