[1] Univ Lausanne, CH-1015 Lausanne, Switzerland
[2] Univ Bern, Inst Social & Prevent Med, CH-3012 Bern, Switzerland
[3] Source Hosp, Infect Dis Serv, Lausanne, Switzerland
[4] Univ Hosp Bern, Infect Dis Serv, CH-3010 Bern, Switzerland
[5] Univ Basel Hosp, Infect Dis Serv, CH-4031 Basel, Switzerland
[6] Univ Hosp Geneva, Infect Dis Serv, Geneva, Switzerland
[7] Univ Zurich Hosp, Infect Dis Serv, CH-8091 Zurich, Switzerland
[8] Cantonal Hosp, Infect Dis Serv, St Gallen, Switzerland
[9] Reg Hosp, Infect Dis Serv, Lugano, Switzerland