[1] Hosp Civils Lyon, Infect Control & Epidemiol Unit, Hop Edouard Herriot, F-69437 Lyon 03, France
[2] Univ Lyon 1, Epidemiol & Publ Hlth Unit, F-69365 Lyon, France
[3] Univ Hosp Geneva, Infect Control Program, Geneva, Switzerland
[4] Fac Med, Geneva, Switzerland