[1] Charite Univ Med Berlin, Inst Hyg & Environm Med, D-14059 Berlin, Germany
[2] Natl Reference Ctr Surveillance Nosocomial Infect, Berlin, Germany
[3] Inst Med Microbiol, Div Hosp Epidemiol & Infect Control, Hannover, Germany
[4] Hosp Epidemiol, Hannover Med Sch, Hannover, Germany